Aerosensor documentation

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Articles

Aerosensor

Quickstart

What follows outlines the basic setup of Aerosensor. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerosensor Setup

Install Aerosensor securely, level, and centred on the bike using a go-pro mount.
Pair your power meter speed sensor to Garmin. We recommend dual sided power meter, and magnet based speed sensor.
Calibrate power meter in Garmin, and set crank length if necessary.
Open ACS CIQ app on your Garmin bike computer.
Choose test type:
1. Road: for general road cycling.
2. Out and back: for cycling out and back along a stretch of road.
3. Velodrome trackless: for velodrome use without Aerodrome lap trigger.
4. Velodrome tracked: for velodrome use with Aerodrome lap trigger.
Connect Aerosensor to CIQ app.
1. Turn on Aerosensor. It should connect automatically. If not:
2. Menu > Connections > Aerosensor.
3. Wait for CIQ app to find device, then click on it to connect.
Input key parameters Menu > Aerosensor Settings > Parameters > Edit Parameters. Most important parameters to set are:
1. Aero device calibration: Start with a value of 1.4.
2. Total mass (your total mass i.e. you + bike + clothing)
3. Wheel circumference You can get from speed sensor info in Garmin, or roll out wheel and measure distance on ground.
4. Power meter scaling This accounts for drive train losses. Typically use 0.98 for all but hub based PMs
5. CTF calibration offset Only necessary if using an SRM PM7 or earlier Power meter. This is the value reported when you calibrate your power meter on the Garmin.
Be sure to “Push Parameters” after exiting this menu to save any changes.
Check connections, and start activity
1. Make sure your power meter and speed sensor are on, by rotating wheel and pedals.
2. If paired then “PWR” and “SPD” icons in top right go green. If not see ACS instructions.
Start activity

That’s it! You are now ready to go aero testing. For accurate results be sure to calibrate your aerosensor every time you change bike or make a substantial change in your position. Don’t worry, you can do this at the same time as testing and post-correct your data, so no specific runs are necessary. See next section.

Calibration

The air “sees” you coming towards it due to high pressure build up ahead of you. For this reason the air at Aerosensor’s location on your bike is slower than freestream. We need to correct for this.

Perform at least two out/backs or 4 laps of velodrome. Be sure to start activity before starting this, and stop activity at the end.
Select valid laps. Go to page 9 of the CIQ app, press menu, then either press up or down arrows or swipe up or down to select laps. Press menu again to toggle valid (“X”) or invalid (no “X”).
Read the new cal value (“New_Cal”). You can either see this at the top of the lap page, or on page 10.
You can post-correct your CdA values by dividing them by this value. This can also be done in aeroworkbook or aeroportal. See relevant sections under “Data analysis”.
CdA_corrected = CdA_reported * Old_cal/ New_cal
Enter new “Aero device calibration” in Aerosensor Settings.
Menu > Aerosensor Settings > Parameters > Edit Parameters.

Aero testing guidance

Reliable aerodynamic testing is reliant on good testing protocols, focus on the following:

CdA data is only as accurate as the inputs. Make sure you check Aerosensor’s settings in the ACS app before every test.
Always calibrate power sensor before starting testing, and ideally before each set of laps or out-backs. Small calibration offsets can result in a big error in CdA measurement.
Always start and end your test block with a baseline repeat.
Try to maintain a constant speed through each run.
For out and back testing we recommend a stretch between 600 and 1000m.
The more out and backs you do, the better the repeatability will be.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Important notes & prerequisites

Important notes

Aerosensor is designed for outdoor paved roads or velodrome use in dry conditions and is therefore not suitable for wet conditions.

The device is not waterproof as it has holes to allow pressure measurement.

Aerosensor must be removed in wet conditions. If you think it will rain whilst you are out riding or the road may be wet in places then take a 3mm hex key with you so you can remove the device and put it in your jersey pocket for the rest of your ride.

Aerosensor will vibrate on rough paved roads. This has no negative impact on measurement quality. However if excessive vibrations occur, or if Aerosensor pitches down after use, please check the got-pro mount screw was sufficiently tight.

Clean Aerosensor with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerosensor requires an ANT+ power and either bike speed or bike speed + cadence sensor. It also requires a Garmin cycling computer.

Bike Computer

Currently to use the ACS you will need a Garmin bike computer that can run Garmin Connect IQ applications at a minimum of SDK 3.1.0. A full list of compatible devices is available on the link below – be sure to check that the device has the “A” symbol, meaning apps.

Note Edge 130/130 plus computers are NOT compatible as they do not allow you to run the CIQ app.

https://developer.garmin.com/connect-iq/compatible-devices/

We will make data fields in the future, allowing you to see data in the standard Garmin context, and also on the Edge 130.

Power Meter (PWR)

Aerosensor requires a quality power meter. Single sided pedal-based power meters are not sufficiently accurate for good aerodynamic data. Remember that the aero data you get will only be as accurate as the power meter used.

Speed (SPD) or Speed/Cadence (BSC) Sensor

For the best accuracy we highly recommend a magnet-based speed sensor. Hub mounted speed sensors or GPS based speed sensors do not have the time resolution necessary for high quality aerodynamic data.

Device mounts

Aerosensor has been designed to work on a variety of different bike bar types, notably the following:

Drop handlebars – usually standard on road bikes and track bikes.
Clip-on time-trial (TT) bars – additions to road and track bikes.
Integrated TT handlebar/cockpit – mostly seen on TT and triathlon specific bikes.

A go-pro mount is required to install Aerosensor – for example one underneath a bike computer mount (sold separately, available on our website in Accessories).

Whilst Aerosensor can be used on most bike setups, there will be some bar variants that may be trickier to setup. Please do not hesitate to contact us at hello@Aerosensor.tech with any questions or for advice on how to best mount onto your bike.

Device basics

Specifications

Dimensions (H x W x D)	135 x 57 x 85mm
Mass	66g
Battery Life	57 hours
Wind speed resolution	+/- 0.1%
Wind angle resolution	+/- 0.1°
Altitude resolution	+/- 10cm

Layout

LED
Power button
Reset button
USB-C bung & charging port
Stem
Height/yaw adjustment screw
Go-pro mount

Button functions

Power button:
- Press and release to turn on.
- Press and hold until LED turns off then release to shut down.
- Press and hold, push reset button, then release for full factory reset. This resets the internal settings used to calculate CdA.
Reset button:
- To be used in case the device becomes unresponsive. Resets device without erasing settings.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Aqua	Normal	On	Unplugged	Normal
Red	Normal	On	Unplugged	Low
Amber	Slow	Off	Plugged in	Charging
Amber	Solid	On	Plugged in	Charging
Green	Slow	Off	Plugged in	Charged
Green	Solid	On	Plugged in	Charged

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Installation

Use the go-pro mount itself to adjust pitch, then the yaw by loosening the height/yaw screw on Aerosensor’s stem (height adjuster) and rotating the unit.

Do not use the aerosensor base to pivot, this can cause damage to the stem.

When installing, it is important to have Aerosensor as far forward and low as possible that the stem allows to minimise influence of rider position.

The base must be at least 20mm above the front wheel.
It should be centred on the bike and facing forwards. Use the front wheel as a reference for yaw alignment.
Aerosensor should be level – use a horizontal object to the side of the bike (like floor markings), and visually align the bottom of Aerosensor with the horizontal line. An example is shown below, where a horizontal line on the wall is used. Note that the device is tolerant to pitch misalignment within +/-5°.

CIQ App

Aerosensor Connection

Make sure that Aerosensor is switched on.

1. Press the menu button on the Garmin head unit.

2. Select “Connections” -> “Aerosensor”.

3. Select the device you want to connect to. Note: it is worth keeping a note of the Device ID for your Aerosensor and Aerobody for your records, especially if you are a coach and have multiple devices for your riders.

Pass-pairing

Pass-pairing is where ACS transmits the power meter and speed sensor ANT+ connection details to Aerosensor, allowing it to connect to them directly.

For this to work the Garmin unit should already be paired with the ANT+ sensors you are using.

Note that Aerosensor requires a power meter (PWR) AND EITHER a speed sensor (SPD) OR speed + cadence sensor (BSC).

The CIQ app should automatically pass on the sensor connections to Aerosensor. In case this does not work, or you have multiple sensors on the bike, follow these steps:

Ensure that a power meter and speed sensor are installed on the bike and paired with the Garmin. Make sure they are on by rotating the wheel and/or pedals/crank, depending on the power meter.
In the ACS menu, select “Connections”->”Pass pair” which will bring up the following screen:

3. Either select the devices individually or select the bottom “Enter to sync” button in purple above. After a short period, the status bar at the bottom of the screen should go green to show Aerosensor matches the Garmin device. Aerosensor connection status icons should go from red to green.

Aerosensor Parameters

To accurately calculate aerodynamic drag, Aerosensor requires some information about you and your bike:

Aero device calibration: This accounts for the fact that the wind slows as it approaches the bike, so the wind speed measured by Aerosensor is always slower than the air far upstream of the bike. Start with a value of 1.4. Typically we see values beweeen 1.1 and 1.45. See ‘Quickstart’ section for more information.
Total mass (kg): includes rider + bike + all accessories used whilst riding with Aerosensor.
Wheel Circumference (mm). If unknown, you can go into the speed sensor settings on the Garmin and you will find the wheel circumference in there once you have ridden far enough for the Garmin to calibrate against GPS.
Power meter scaling: Default value is 1.0. If using pedals or crank we need to account for drivetrain losses. A typical value would be 0.98, i.e. 2% drivetrain loss.
CTF calibration offset: Used for CTF power meters.
Time av period: This is the time period used by Aerosensor to average the CdA value, default is 30 seconds.
Reference Crr: Rolling resistance coefficient (used if known), default 0.004. For an indoor velodrome you should use 0.002 (half the road value). You can find typical crr values for a range of tyres at https://www.bicyclerollingresistance.com/
Valid speed min: minimum speed (kph) for valid CdA automatic lapping. The CdA calculation is started when you go above this speed, and stopped when you slow down below this speed. The device automatically creates laps for each CdA measurement period.

Editing Parameters:

1. Go to Menu-> Aerosensor Settings-> Aerosensor

2. Ensure that the parameters have been received (“20 parameters received” under “Get Layout” button header). If not, select “Get Parameter”.

3. Select “Edit parameters” ->select setting to be edited on “Settings Edit Menu”. Use buttons to edit value. Click on “Save”.

4. On return to “Settings Edit Menu” note changed parameters shown in red.

5. Return to “Aerosensor Parameters” menu.

6. Select “Push layout” to push settings to Aerosensor. If successful, “Sent successfully” will show.

It is important you check these frequently, especially total mass and wheel circumference if changing between bikes for example.

Velodrome testing – Track layout

When Aerosensor is in track calculation mode it uses lap distance and speed to calculate lean angle to compensate for centre of gravity location. This only works when Aerodrome is being used. A typical track layout is shown below, of which you can input the track measurements by editing parameters directly in the CIQ app.

You can measure the track by measuring relative distance of corner start and end, using the distance markers along the track. This does not need to be very accurate – within a few meters is fine.

Measuring the track:

Measure the distance from the tapeswitch location to the start and end of each corner.
Use these to calculate the total distance of the two straight sections.
Corner length = track length – total straight lengths
Corner radius = corner length / pi
Transition length is the distance it takes for the rider to transition from the straight to the corner. Typical value is 10m.

Example:

Total track length = 250m.
C1 start = 10m
C1 end = 95m
C2 start = 135m
C2 end = 220m
Corner length = C1 end – C1 start – transition= 95 – 10 – 10 = 75m
Corner radius = 75/pi = 23.9m

Editing Parameters:

1. Go to Menu-> Aerosensor Settings->Track. and ensure that the parameters have been received. If not, select "Get Layout".

Select “Edit layout” and select setting to be edited on "Track Edit Menu".

3. Use buttons to edit value and click on "Save".

4. On return to “Track Edit Menu” note changed parameters shown in red.

5. Return to “Aerosensor Track Layout” menu.

Velodrome testing – Calculation mode

At the velodrome Aerosensor can ignore the barometer, since elevation is roughly constant, and should use the track map. If the track map is not known, or Aerodrome is not available, you can use the trackless mode. To use Velodrome mode:

Go to Menu-> Aerosensor Settings->Calculation Mode.
Select the model you require:
1. Road
  For road riding.
2. Velodrome Trackless
  Assumes constant elevation but ignores track layout. This is for when you are not using a lap trigger (Aerodrome) or the track layout is unknown.
3. Velodrome Tracked
  Assumes constant elevation AND uses the track layout. This is for when you are using Aerodrome and know the track layout, as entered in ‘Aerosensor Settings->Track’.
Wait until the mode changes as required, in the menu heading.

Screen sequence shown below:

Aerosensor demo mode

This is for diagnostic purposes and can generally be ignored.

Aerosensor information

Go to Menu -> Aerosensor settings -> about

Here you can see information about your Aerosensor device, including battery level, firmware version and serial number. Battery voltage is also included as it is useful for diagnostic purposes.

Calibration

aerosensor calibration

For those in a hurry

No time to read the details? Here’s the short version:

Why calibrate?
Air slows down ahead of the bike, so Aerosensor’s dynamic pressure reading must be scaled up. This is called Aero Device Calibration in the CIQ app, or simply Aero Calibration or Cal in Aeroportal and Aeroworkbook.
What affects calibration?
Bike setup, rider position, sensor location – even helmet choice can make a small difference.
How is it done?
A calibration is calculated for every out-and-back run or lap of the velodrome, assuming zero average headwind.
What affects calibration accuracy?
Since we assume zero average headwind anything affecting the wind consistency will affect this. Wind variability (shown as Hwind SD – headwind standard deviation in particular) will degrade accuracy.
How accurate does it need to be?
Keep the CIQ app calibration factor within 5% of the measured value:
- For out-and-back tests, this is critical because it also affects altitude correction.
- For velodrome tests, this is less critical. Since altitude is not used (assumed to be constant) calibration can be corrected perfectly afterwards.
How do I use it in post-processing?
Both Aeroportal and Aeroworkbook offer Auto Cal, which applies the correct factor automatically. They also show:
- 🟢 Green: repeatable calibration, stable wind → Auto Cal can be used confidently.
- 🟠 Orange: some variability → check baseline repeatability; only use Auto Cal for smaller changes (<2%).
- 🔴 Red: inconsistent data → Auto Cal not valid; only test changes that don’t affect calibration, with a constant calibration.
Why does this matter?
All aero devices require calibration, even if others hide it. Aerosensor gives you full visibility and control, so you can trust the results based on what you saw and tested. It’s a little extra work, but it leads to more reliable data.

Introduction

aerosensor calibration

Introduction

What’s the problem?

As air approaches a cyclist, it slows down due to the build-up of high pressure in front of the bike and rider.
The CFD image below (from this site) shows air speed around a rider in three positions. We’ve added a red arrow to mark the typical Aerosensor location.

You can see:

Rider position changes how much the flow slows down.
In some cases, the slowdown begins well upstream of the bike.

Our own wind tunnel tests confirm this effect (figure 2). Even one metre in front of the bike, air speed is still reduced by 2–3%. Unfortunately, there’s no practical way to mount a sensor far enough forward to avoid this.

This isn’t unique to Aerosensor – it’s just physics. All on-bike aerodynamic devices face the same challenge. The best we can do is minimise the effect by placing the sensor as far forward as possible, then correct for it through calibration.

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What’s the solution?

We overcome this problem by calibrating the sensor.

In still air, road speed and true airspeed are the same. By comparing road speed to the sensor’s measured airspeed, we can calculate a calibration factor that scales the reading back to freestream conditions.

As long as the rider position and setup remain unchanged, this calibration factor will also stay constant.

Technical detail

aerosensor calibration

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Technical detail (optional bedtime reading..)

If you’re mainly interested in how to use Aerosensor, you can skip this section. The details here are for those who want to understand the physics behind the calibration process.

Aerodynamic basics

Aerodynamic force generally scales with dynamic pressure - the pressure increase you’d get if moving air was brought to rest.

The formula for this is:

$p_{dyn}=\frac{1}{2}\rho V^2$

Where:

$p_{dyn}$ = dynamic pressure (Pa)
$\rho$ = air density
$V$ = Air speed.

Since drag force is proportional to dynamic pressure, we can calculate a drag coefficient, $C_dA$ :

$CdA\ =\ \frac{Drag}{p_{dyn}}$

Dynamic pressure is just the difference between total pressure (the pressure measured by the little tube in the centre of aerosensor) and the static pressure (ambient pressure):

$pDyn\ =\ p_T-p_S$

Measuing dynamic pressure

Aerosensor cannot measure the true static pressure because it sits close to the bike, where the flow is already slowing down. Instead it measures a slightly different static pressure, $p_{aero}$ .

From aerodynamic theory the difference can be expressed as the pressure coefficient, $Cp_{aero}$ .

$C_{p_{aero}}=\frac{p_{aero}-p_s}{p_T-p_s}$

What aerosensor actually measures is $dp$ :

$dp=p_T-p_{aero}$

Expanding this and substituting in $C_{p_{aero}}$ :

$dp=(p_T-p_S)-(p_{aero}-p_S)$

$dp=p_{dyn}-C_{p_{aero}} p_{dyn}$

$dp=(1-C_{p_{aero}}) p_{dyn}$

Rearranging:

$p_{dyn}=\frac{dp}{1-C_{p_{aero}}}$

Aero device calibration

This leads to the aero device calibration, $cal$ :

$cal=\frac{1}{1-C_{p_{aero}}}$

So the corrected dynamic pressure is calculated by:

$p_{dyn}=cal\times dp$

How it's calculated in practice

In the real world, where there may be wind, calibration is derived from an out-back run or a single lap of a closed circuit, based on the assumption that the average wind is zero.

Aerosensor calculates:

The average measured pressure $dp$ .
The average dynamic pressure inferred from wheel speed.

Dividing (2) by (1) gives you the calibration factor for that run.

Post-correcting for updated calibration factor

CdA can be post-corrected for calibration factor as follows:

${CdA}_{new}=\ {CdA}_{old}\times\frac{{cal}_{old}}{{cal}_{new}}$

Where:

$CdA_{old}$ = CdA reported by Aerosensor.
$cal_{old}$ = Calibration factor entered in settings in CIQ app.
$cal_{new}$ = new calibration factor you want to apply.
$CdA_{new}$ = corrected CdA.

Both Aeroportal and Aeroworkbook do this automatically when you change the calibration factor.

However, this correction is not perfect in every case. To calculate altitude, we need accurate dynamic pressure. On velodromes, altitude is ignored, so calibration can be corrected perfectly afterwards. On out-and-backs, large errors in calibration will reduce CdA accuracy.

For example:

On an out-back run, a 10% error in calibration, combined with a 25% variation in speed across the lap, results in about a 1.5% error in CdA.
If speed were perfectly constant through the lap, the error would be zero.

Keeping your speed consistent between runs reduces the impact of calibration error on your results.

Recommended protocol

aerosensor calibration

Recommended Protocol

General approach: Run a baseline first, update your calibration factor, then continue with your tests.

Velodrome: At least 1500 m (≈6 good laps of a 250 m track).
Out-back: At least 3 out-backs, each 600–1000m in length.

You can select valid laps in the CIQ app and read off the average calibration, or use Aeroportal / Aeroworkbook to do the same.

There are a few things to bear in mind based on test type.

Indoor Velodrome

Calibration is easiest on an indoor Velodrome because it there is no wind. A couple of points to watch out for:

Ride alone: Other riders disturb the air, effectively giving you a false tailwind.
Limit calibration laps: Only use the first ~5 laps for calibration (set under Advanced settings → Max calibration laps in the Aeroworkbook and under Edit run in Aeroportal). After that, you start creating your own “tailwind.” Think of the velodrome as a giant cup of tea and yourself as the spoon — circulation builds gradually, but eventually it affects your data.

Outdoor Velodrome

Outdoors you don’t generate your own tailwind, but you will almost always encounter some ambient wind.

Collect at least 1500m of data (≈6 laps of a 250 m track).
More laps generally improve reliability.

Out-Back testing

Two main issues affect out-back calibration:

Traffic: Passing cars, motorbikes, or cyclists disturb the air and create headwinds or tailwinds. The more traffic, the less reliable your calibration.
Consistency of start/end point: Local features (trees, buildings, hedges) influence wind patterns. If your “out” and “back” sections don’t overlap exactly, calibration accuracy suffers.

Best practice:

Choose quiet roads and times with minimal traffic.
Keep start/stop points, acceleration, and deceleration as consistent as possible.
The more consistent your testing, the more consistent the results.

Aerobody

Quickstart

What follows outlines the basic setup of Aerobody. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerobody setup

1. Install device using Garmin ¼-turn mount.

2. Position device. Using your hand to check, rotate Aerobody so the head sensor is picking up your chin. Tighten mount screw to lock in position.

3. Open either ACS or Aerobody datafield on Garmin device.

4. Connect Aerobody to CIQ app.

a. Turn on Aerobody. It should connect automatically. If not:

b. Menu > Connections > Aerobody.

c. Wait for CIQ app to find device, then click on it to connect.

5. Set your datum position using the app or datafield.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Device basics

Specifications

Dimensions (H x W x D)	36 x 32 x 64mm
Mass	37g
Battery Life	9 hours
Head position resolution	+/- 1mm
Chest position resolution	+/- 1mm

Layout

LED
Power button
Reset button
USB-C bung & charging port
Head sensor
Chest sensor
Quarter-turn mount

Button functions

Power button:
- Press and release to turn on.
- Press and hold until LED turns off then release to shut down.
Reset button:
- To be used in case the device becomes unresponsive.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Aqua	Normal	On	Unplugged	Normal
Red	Normal	On	Unplugged	Low
Amber	Slow	Off	Plugged in	Charging
Amber	Solid	On	Plugged in	Charging
Green	Slow	Off	Plugged in	Charged
Green	Solid	On	Plugged in	Charged

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Important notes & prerequisites

Important notes

Aerobody uses optical sensors for measuring your body position, so keeping the sensor lenses clean and free from debris is critical for good performance.

The USB port should be kept dry and free from debris. After charging, please ensure that the bung is replaced firmly.

Although Aerobody is splashproof, it is not designed to operate in wet conditions. Please ensure it is removed if outdoors and raining.

Clean Aerobody with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerobody doesn’t require any other devices to work; you will need a Garmin cycling computer however.

Device mounts

Aerobody has been designed to work on a variety of different bike bar types, notably the following:

Drop handlebars – usually standard on road bikes and track bikes.
Clip-on time-trial (TT) bars – additions to road and track bikes.
Integrated TT handlebar/cockpit – mostly seen on TT and triathlon specific bikes.

Aerobody is supplied with a quarter-turn mount suitable for most bike setups.

Whilst Aerobody can be used on most bike setups, there will be some bar variants that may be trickier to setup. Please do not hesitate to contact us at hello@Aerosensor.tech with any questions or for advice on how to best mount onto your bike.

Installation

Aerobody has a standard Garmin quarter-turn mount. It should be positioned on the stem using a compatible bike mount adapter such as the one supplied with the unit. The screw on the quarter-turn mount allows pitch adjustment of the entire unit.

The forward (head) sensor should be aligned approximately with the chin and the chest sensor points at the chest.

To align, support the bike either in a turbo trainer, or by asking someone to support the bike. Sitting on the bike in your normal riding position watch the display whilst moving two fingers up and down from your chin towards the unit, and ensure that the measurement tracks movement of your fingers.

CIQ App

Aerobody Connection

Make sure that Aerobody is switched on.

Press the menu button on the Garmin head unit.
Select “Connections” -> “Aerobody”.

3. Select the device you want to connect to. Note: it is worth keeping a note of the Device ID for your Aerobody for your records, especially if you are a coach and have multiple devices for your riders.

Set Reference

The CIQ app shows your body position relative to a reference which you can set as follows:

Got to Menu-> Aerobody Settings->Set Reference.
Get into your ideal position on the bike. To do this support the bike in a turbo trainer, or ask someone to support it for you, and get into your normal riding position.
Select “Measure”. This will give you a 5 second countdown to get in position, then will take a 2 second average of your position. When complete the measurements will show in red to indicate the new values are unsaved, and the “Save” button will be highlighted.
Click “Save” to send the new position to Aerobody. Wait for the head and chest display to update to green, and the save button to turn grey and show “Saved”.

Set Null Zone

The body position fields in the CIQ app will turn red if you are higher, or blue if you are lower, than your reference position. It will be white if you are within a set “null zone” around your reference position. As an example, a 1.5cm null zone means that the rider moving between -1.5cm and +1.5cm of their reference head or chest position will remain white whilst riding. Anything outside of these values are considered “out of position” will be red or blue depending if you are too high or too low.

The null zone may be set as follows:

Got to Menu-> Aerobody Settings->Set Null Zone.
The buttons can be used to adjust in multiples of 1cm and 0.1cm as necessary.
Click “Save” to send the new position to Aerobody.

Aerobody information

Got to Menu -> Aerobody settings -> About

Here you can see information about your Aerobody device, including battery level, firmware version and serial number. Battery voltage is also included as it is useful for diagnostic purposes.

CIQ Datafield

Please refer to the Aerobody CIQ Datafield section here.

Aerodrome

Quickstart

What follows outlines the basic setup of Aerodrome. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerodrome Setup

Install tapeswitch across track, securing with duck tape.
Position Aerodrome about 1-2 meters downstream of the tapeswitch, close to track, oriented so that the buttons are closest to the track as shown.
Ensure Aerodrome blue light is flashing
When Aerosensor is on and within a few meters of the Aerodrome the light will flash to show it is able to communicate with it. This ensures radio signal is strong enough to work. It only needs to pick up Aerosensor’s signal for 1-2 meters after the tapeswitch is crossed.
Open ACS in “Velodrome Tracked” mode.
This assumes no elevation changes, and uses the trackmap to correct for cyclist lean angle.
Edit track map in ACS.
See section in CIQ app documentation.

Remember to start an activity on the Garmin before starting to ride. Aerosensor will automatically create new laps every time you cross the tapeswitch. Note that the data appears on the Garmin a couple of seconds after the end of lap, once Aerosensor has finished averaging data for the lap.

Aero testing guidance

Reliable aerodynamic testing is reliant on good testing protocols. Here are a few tips for best results.

CdA data is only as accurate as the inputs. Make sure you check Aerosensor’s settings in the ACS app before every test.
Always calibrate power sensor before starting testing. Small calibration offsets can result in a big error in CdA measurement.
Always start and end your test block with a baseline repeat.
Try to maintain a constant speed through each run.
For velodrome testing we recommend 6-8 laps per configuration.
The more laps you do, the better the repeatability will be.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Device basics

Specifications

Dimensions (H x W x D)	34 x 76 x 76mm
Mass	66g
Battery Life	28 hours
Timing resolution	+/- 1ms

Layout

Power button
LED
Reset button
USB-C charging port
Tapeswitch port

Button functions

Power button:
- Press and release to turn on.
- Press and release to shut down.
Reset button:
- To be used in case the device becomes unresponsive.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Cyan	Solid	On	Unplugged	Normal
Lilac	Solid	Trigger	N/A	N/A
Amber	Solid	On	Charger	Low
Green	Solid	Off	Charger	Charging
Blue	Solid	On	Computer	Charging
Light blue	Solid	Off	Computer	Charged
Any	Flash	On	Aerosensor connected

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Important notes & prerequisites

Important notes

Aerodrome uses a Tapeswitch cable as a lap trigger – the cable should not be pinched or bent. Bending with a bend radius less than 4mm will permanently damage the product.

The USB port and Tapeswitch port should be kept dry and free from debris.

Although Aerodrome is splashproof, it is not designed to operate in wet conditions. Please ensure it is not used outdoors when it is raining.

Clean Aerodrome with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerodrome requires Aerosensor device and a Garmin cycling computer.

Installation

As Aerodrome will likely be used on a live track or a public road, it is critical that you have permission to use the device and/or have taken appropriate measures to ensure not only the safety of you and other riders, but also to prolong the life of the device itself.

The tapeswitch should be placed so that the flat side is against the track or road, and the ridge on the upper side. Using duck tape, secure the tapeswitch across the line the cyclist will be following, be it on the track or the road. Secure at the far ends with tape, and placing a further piece of tape along the length, just holding down the upstream side of the tapeswitch.

Tape along the tapeswitch, not across it (as below).

Aerodrome listens for Aerosensor and the LED flashes when it receives data. It is only able to transmit the lap trigger when this is happening.

For optimal radio performance, make sure Aerodrome is situated in a position where it can receive data from Aerosensor when bike is at or just past the Tapeswitch. It is normally best to position 1-2m downstream of where the lap trigger is placed. Orient the device so that the buttons are closest to the track, as shown in images below.

Plug the tapeswitch plug into the Aerodrome socket and turn on. The power light should illuminate. You can check it is working by pressing on the tapeswitch. The LED will turn purple for 1 second to indicate a lap trigger.

Aerodrome should be placed on the floor well clear of any area the rider is likely to pass. Secure the tapeswitch cable to the floor with duck tape to avoid trip hazards.

Note that currently Aerodrome cannot distinguish between multiple Aerosensor’s running on track. It will only work correctly when a single rider is on track.

CIQ App

Aerodrome Connection

Aerodrome uses Aerosensor, so no specific settings are required in the CIQ App.

Please refer to the Aerosensor section here.

Garmin CIQ Apps & Datafields

Aerosensor Cycling System CIQ App

Overview

The Aerosensor Aerodynamic Cycling System (ACS) Connect IQ app is required to seamlessly integrate our devices with your Garmin bike computer, providing real-time aerodynamic data and further insights during your ride, and recording your data to a FIT file for further analysis.

Installation

The Aerosensor ACS CIQ app can be downloaded from the Garmin Connect IQ website:

https://apps.garmin.com/

Simply search for “Aerosensor” and the app will come up, or use this link:

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

Install to the Garmin head unit as per the instructions on the CIQ app website.
Start ACS by going to the Connect IQ menu on your Garmin (see Garmin instructions) and then selecting “Aerosensor ACS”.

ACS screen layout

FIT file recording status:
Red square = not recording
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status:
Green = Connected.
Orange = Searching.
Red = Disconnected.
Aerosensor battery status.
Back key
Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key.
This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerobody CIQ Datafield

Overview

Aerobody is a device that mounts on your stem and measures the distance to your head and chest. This is a good indication of your overall body position.

The Aerobody datafield allows you to view your body position data in the context of your normal Garmin views. You can add it in the same way you would add any other data such as speed, power, time etc. It also adds your aerobody data to the fit file so you can view it after your ride.

Installation

Search for Aerobody on the ConnectIQ store and follow instructions to install.

Once installed, on your Garmin select the data screen (in your chosen activity profile) and edit the field where you want the data to appear.
Select Connect IQ from the list.
Select Aerobody from the list.

Note that aerobody really needs a full screen width field to display correctly as it displays both head and chest positions.

Pairing

Turn on your Aerobody device.

The Aerobody datafield will automatically connect to the first Aerobody signal it picks up. It saves this so that next time it will look for the same physical device.

If you need to switch to a different Aerobody device, firstly make sure that only that one is switched on and in range (roughly 10m) of the Garmin unit, the follow the following steps.

Make sure that Garmin Connect app is installed on your phone and paired with your Edge unit.
Turn on your Garmin and the Aerobody device.
In either Garmin Connect or the Garmin ConnectIQ app, select your device, then go find the datafield app. Open settings.
Move the slider next to “Reset paired device” to the right.
Click “Save”. The display on the Garmin should show “Reconnecting” for 3 seconds then switch back to the data view. Ensure that a surface is within 300mm of the Aerobody device in order to make sure it is reading data.

Setting datum

Aerobody allows you to set a datum, which you can think of as a target position for you to maintain whilst riding. The head and chest fields will go red if you go above this; blue if below, outside of a “null zone”, the dimensions of which you can modify in the settings. You can also set an audible alert to warn you when you are outside of your target range. By default the relative position is shown in the fields, which is the distance between your current position and the datum. This can be changed to absolute position in the datafield settings.
To set your datum, follow these steps:

Get on the bike, ready to get into position. Use a turbo-trainer or friend to support it.
In settings, put the “Set datum” slider to the right. Click “Save”.
On the datafield it will give you a countdown of 3 seconds to get into position.
The datafield It will then average your position and save it.

Now when you are in the correct position the display should have an uncoloured background. If you are too low it goes blue; too high it goes red.

Testing

aerosensor testing

Introduction

Here you can find all the information you need for accurate aerodynamic testing on the road or track. Open the appropriate section.

You can download a pdf of these instructions by clicking the button below.

Expected repeatability

aerosensor testing

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Expected repeatability

Outdoors you should be able to achieve the following repetability so long as average wind speed is less than 25% of cycling road speed. If wind speed is above 50% we do not recommend aero testing.

Out-back testing

+/-1.5%

Outdoor velodrome with aerodrome

+/-1.0%

Indoor velodrome with aerodrome

+/-0.5%

For good repeatability careful setup is essential. In particular:

Ensure power meter is calibrated before each run.
Make sure total mass is correct for every run.
Carefully measure the loaded circumference of the wheels (seated roll-out).

Terminology

aerosensor testing

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Terminology

For clarity, its please note the following terminology taht will be used througout this section.

Session

A series of runs covering various bike and rider configurations.

Run

A set of consecutive laps with the bike and rider in a single configuration.

Lap

Either a single track lap, or an “Out” or “Back” leg in out-back testing.

Out Lap

Segment riding at speed away from your starting point.

Back Lap

Segment riding at speed towards your starting point.

Out-back

A pair of consecutive Out and Back Laps.

Baseline

A known starting configuration of bike and rider.

Aerosensor settings

aerosensor testing

Aerosensor settings

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Basic settings

To function correctly, Aerosensor requires the following inputs, entered in the ConnectIQ app here:
Menu → Aerosensor settings → Basic settings:

Aerosensor calibration

Calibration is reported for every run and depends on bike setup. Minor changes (helmet, wheels) have little effect, but adjustments to handlebar height, reach, or sensor position can significantly impact results.

Begin each session with 2 runs and compare reported calibration to the current setting.
If it differs by more than 5%, update it before continuing.

Total mass

Mass affects acceleration, gravity, and rolling resistance, making it critical for accuracy.

Weigh yourself before each session, including bike, gear, and accessories.
Carry fluids on the bike so total weight remains consistent as you drink.
If you refill bottles or use the loo, re-weigh before continuing.

Wheel circumference

Measure the circumference of only the wheel with the speed sensor. This depends on tires, wheels, pressure, and system weight. To measure:

Align a piece of tape on the wheel and ground.
Sit on the bike and roll forward one full revolution.
Mark the new ground position and measure the distance between marks.

Reference Crr (Coefficient of Rolling Resistance)

Find Crr values for your tires and pressure at: https://www.bicyclerollingresistance.com/

Crr depends on road roughness but has a small, consistent effect on CdA measurements.
If testing on a velodrome (wood track), reduce Crr by ~40%.
Example: A road Crr of 0.0035 should be 0.002 on a velodrome.

If unsure the following table shows some typical values for smooth tarmac.

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Tyre Type	Tyre pressure
Tyre Type	60psi	80psi	100psi	120psi
CLINCHER: TT	0.0044	0.0037	0.0033	0.0030
CLINCHER: ALL-ROUNDER	0.0056	0.0047	0.0042	0.0040
CLINCHER: ALL-WEATHER	0.0072	0.0061	0.0055	0.0052
TUBELESS: TT	0.0033	0.0028	0.0026	0.0024
TUBELESS: ALL-ROUNDER	0.0049	0.0042	0.0037	0.0035
TUBELESS: ALL-WEATHER	0.0057	0.0050	0.0044	0.0041
TUBULAR	0.0053	0.0046	0.0042	0.0039

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Advanced Settings

These are settings that you are likely to change less frequently, but nevertheless important. You can find them in the CIQ app here:
Menu → Aerosensor settings → Advanced settings:

Power Meter Scaling

Some power is lost in the drivetrain due to friction (chain, bearings, derailleur, etc.).

Pedal, crank-arm, or spider-based power meters → Set to 0.98 (accounts for ~2% drivetrain loss).
Hub-based power meters → Set to 1.00 (measures power directly at the wheel).

CTF Calibration Offset

For SRM PM7 and older power meters only. Enter the calibration value displayed on your Garmin after calibration (typically ~520).

Time Averaging Period

CdA (not CdA lap) is a rolling average over this time period. It does not affect lap values (e.g., out-back or track testing).

Recommended: 30 seconds (default).

Valid Brake Deceleration

AeroSensor automatically starts a new lap when braking to exclude braking forces from calculations.

Default: 1 m/s²
If using Aerodrome lap trigger: set to 10 m/s² to avoid inadvertently triggering laps for example when going up banking after last lap.

Valid Speed Min

Laps start automatically when speed rises above this threshold.

When testing without Aerodrome lap trigger, set it just below target test speed.
Why? Power meters and speed sensors have small time offsets, which can introduce drag measurement errors if accelerating hard through a low threshold.
Hysteresis: Once speed exceeds the threshold, Aerosensor will not trigger another lap unless speed drops 1 m/s (3.6 km/h) below it.

Braking Time Offset

When braking, Aerosensor discards the last N seconds of data to prevent braking forces from affecting lap CdA calculations.

Recommended: 5 seconds (default).

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Aerosensor Setting Summary

Basic settings

Menu → Aerosensor settings → Basic settings

Setting	Default	Note
Aero device calibration	1.18	Measure yours in testing. Start with 1.4 if unsure.
Total mass	75 kg	Weigh before testing. Includes bike etc.
Wheel circumference	2115 mm	Measure with weighted rollout.
Reference Crr	0.00375	Look up (see table above)

Advanced Settings

Menu → Aerosensor settings → Advanced settings

Setting	Default	Note
Power meter scaling	0.98	Unless using hub based, keep at this value.
CTF Calibration offset	0 Hz	Enter value shown on Garmin after power meter calibration (SRM PM6/7 only).
Time av period	30 s	Rolling average period for CdA
Valid brake deceleration	1 m/s²	Auto lap if brake with deceleration greater than this.
Valid speed min	25.2 kph	Auto lap when speed goes above this value or drops below.
Braking time offset	5 s	Data within this time of braking event is discarded from CdA calculation.

Testing Checklist

aerosensor testing

Testing checklist

Here is a handy checklist to help make sure you are ready to test!

Before Opening CIQ App

Speed sensor paired to Garmin?
Power meter paired to Garmin?
Power meter calibrated?
Power meter auto-cal off (if possible)?

Open CIQ App

Set correct testing type.
Connected to Aerosensor?
Aerosensor paired with speed/power sensors?

Aerosensor Settings

Essentials (Check Before Every Session)

These settings have a major impact on accuracy and must be verified before each test:

Aerosensor calibration set? (Check after 3× out-and-backs; update if >5% off).
Total mass correct? (Weigh before each session; includes rider, bike, and gear).
Wheel circumference measured/set? (Ensure correct value for current tire pressure).
Reference Crr correct? (Adjust for road/velodrome).
Valid speed min set? (Just below target test speed for out-back/track testing).

Less critical (Minimal Impact on Data, Adjust as Needed)

Valid brake deceleration set? (1 m/s² default; 10 m/s² for Aerodrome testing).
Braking time offset set? (Default: 5s).
Time averaging period set? (Default: 30s; only affects rolling CdA, not lap values).

Aerobody Settings (if applicable)

Aerobody connected?
Aerobody datum set?

Session Protocol

aerosensor testing

Session protocol

The testing protocol is the same for all test types.

Aero calibration

It is really important to consider the aero calibration when designing your run plan.

Aerosensor reports a calibration factor for each run to account for airflow slowing as it approaches the bike.

You need to consider the following in order to handle it correctly:

After the first baseline run, update the aero cal in the ACS app.
During testing, if it shifts by more than 5%, update it in the app to minimize altitude calculation errors.
- If this happens in out-back testing, update value then repeat the run.
Expect consistent aero calibration for the same configuration.
Biggest changes occur with body position, stack height, bar angle, etc.

Run plan

Baseline consistency is critical in aerodynamic testing. A known, repeatable configuration ensures accurate comparisons.

Start with two baseline repeats to check system repeatability. Initial drift is common due to power meter offset stabilization and the rider settling in.
End with a baseline run to detect any drift over the session.
Don’t leave more than 10 runs between baselines.

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Run	Configuration	Power meter cal	Aero cal
1	Baseline	Calibrate before run	Last known, or 1.400
2	Baseline (repeat)	Calibrate	Update to calculated
3	First config change.	Calibrate	Keep as last.
4...	Subsequent changes..	Calibrate	Keep as last.
Last	Baseline (final repeat)	Calibrate	Keep as last.

Out-back test protocol

aerosensor testing

Out-back testing protocol

This testing is used when a track is not available.

Road selection criteria

Select a stretch of road, or smooth paved track with the following characteristics:

Traffic: Minimal traffic is best. Aim for fewer than 2 cars per direction per run.
Length: Road should allow 600–1000m of cycling at target speed.
Curvature: Gentle bends are fine, but avoid sections requiring braking or leaning >20°.

Run protocol

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Aim for your target speed, with “Valid speed min” set just below it.
Get into position before reaching this speed.
Around 5 seconds after hitting valid speed, Garmin beeps to acknowledge new lap.
Lap starts when speed threshold is reached.

Ride in Position (600–1000m)

Maintain a steady speed.

Brake Hard to End Lap

Lap automatically ends when deceleration exceeds “Valid brake deceleration”.
The last ~5 seconds of data are excluded from CdA calculation (“Braking time offset”).

Turn Around

Turnaround must take at least 5 seconds to ensure proper lap separation.

Repeat Steps 1–4 in the Opposite Direction

This forms your "Back" lap after completing the "Out" lap.

Complete 3 Out-Back Pairs

Three out-back pairs are recommended because:
- They ensure repeatability of results.
- More data improves accuracy, balancing time vs. quality.

End the Session

After the last Back lap, stop the bike, then press Start/Stop button on Garmin.

Velodrome test protocol with Aerodrome

aerosensor testing

Velodrome testing protocol (with Aerodrome)

This protocol applies to both indoor and outdoor velodromes.

Aerodrome provides highly accurate lap timing (better than 1 ms), generating a separate CdA measurement for each lap. This allows precise tracking of repeatability throughout the session as well as improved accuracy of the data.

Run protocol

You can only test with a single rider on track at any one time.

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

If you are running multiple riders (but only one on track at any one time):

Ensure only 1 aerosensor is switched on. This avoids interference with aerodrome signal.
If using lap logger, ensure only 1 Garmin is running the ACS app. This avoid interference with the lap logger.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Take 1–2 laps to build up to target speed as you normally would.

Start Flying Lap

Cross the lap trigger line at your target speed to begin the first flying lap.

Complete Test Laps

Ride 1,500–2,000m at a steady speed (6–8 laps on a 250m track).
Hold position until you cross the lap trigger at the end of your last lap.

Slow Down After Final Lap

Reduce speed gradually after your last fast lap.

End the Session

Bring the bike to a stop, then press Start/Stop button to end the FIT file recording.

Velodrome test protocol without Aerodrome

aerosensor testing

Velodrome testing protocol (Without Aerodrome)

Without Aerodrome, Aerosensor cannot automatically segment data into laps or identify corner geometry. However, you can still achieve good results by following this method.

Run protocol

You can only test effectively with a single rider on track at any one time.

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Take 1–2 laps to build up to target speed.
Keep speed below "Valid speed min" during this phase.

Start Flying Lap

Aim to accelerate above “Valid speed min” at the start of your first flying lap.
Alternative: Use a Garmin remote lap trigger or the Garmin lap button to manually start the lap when crossing the start/finish line

Complete Test Laps

Ride 1,500–2,000m at a steady speed (6–8 laps on a 250m track).

Decelerate After Final Lap

Reduce power naturally after crossing the start/finish line at the end of your last flying lap.
Alternative: Use the Garmin remote lap trigger to manually end the lap.

End the Session

Bring the bike to a stop, then press Start/Stop button to end the FIT file recording.

Data analysis

For most users, we recommend using our Aeroportal website. On the portal you are able to process, analyse, edit and save your data.

You can create an account on Aeroportal and link it to your Garmin account. This integration allows for the automatic transfer of data from your Garmin device to the portal and the Excel tool, eliminating the need for manual file transfers.

You can also use our aeroworkbook macro-enabled Microsoft Excel workbook for processing and analyzing data. This tool is straightforward, reliable, and well-suited for a wide range of use cases.

Data Workflow:

Record Activity: Complete your session and save the FIT file on your Garmin device.
Automatic Upload: Garmin uploads the FIT file to Garmin Connect via Bluetooth on your smartphone.
Aeroportal Sync: Aeroportal automatically imports the FIT file from Garmin Connect.
Aeroportal or Excel Tool Download: View your data online on the portal or download the data directly to your computer through the Excel Analysis Tool.

This process ensures a seamless and efficient workflow from recording to analysis.

See articles below for detailed instructions.

Aeroworkbook

aeroworkbook

Overview

Our AeroWorkbook is a macro-enabled Microsoft Excel workbook that enables easy analysis of FIT files generated with the Aerosensor ACS Garmin Connect IQ app.

Its main features are as follows:

Download FIT files from the our AeroPortal cloud server.
Import FIT file data.
Correct parameters.
Add descriptions and notes to each run.
Select valid laps.
Calculate out-back, lap and run averaged data.
Display histograms showing wind variation.

Quick start

For those in a rush, here is a brief overview of how to use AeroWorkbook:

Click on Load FIT files on the Control This loads either from a local directory or the cloud, depending on whether or not you have Use cloud set to True or not. You can load more than one fit file at once.
Files are each loaded into separate tabs in the AeroWorkbook.
On each run tab, select Valid laps by adding or removing an X in the appropriate column. Laps with an X next to them are the laps that will be used for the run calculation.
If required, you can change the values of the parameters used for calculation.
Either click Recalculate Sheet on that sheet, or click Recalculate on the Control worksheet to recalculate all runs.
Final run data is shown in the Summary.

Installation and Setup

aeroworkbook

Installation and Setup

Download

You can download the AeroWorkbook here:

https://info.aerosensor.tech/docs/start/downloads/excel-tools/

Prerequisites

Since V1.5.5 the FIT files are loaded directly within the Microsoft Excel macros, so Java is no longer required. Similarly the script files which used to be required on mac are no longer needed!

Since there is no longer anything to check on your system the “Check system” button has also been removed.

Checking your system

After carrying out these steps, use the Check System button on the Control worksheet to check that everything is set up correctly on your computer. You should see something like the following. If there is a red x by any item you should check you have done everything correctly.

Setup

Before you load any data you will need to set the aerotool up depending on the testing you are doing. The settings are all on the Control worksheet.

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Basic settings

Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Testing type

Either track or out-back.

Delete raw data

When a FIT file is loaded the raw FIT file data is loaded into worksheets named after each of the 3 data types (record, lap, session). If you want to check the raw data set this field to false. For most purposes you can leave it as true.

Auto calibrate

Aerotool calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Speed units

Select an option from either kph or mph.

Use cloud

Set to true if you want to load data from aeroportal.
Set to false to import locally saved FIT files.

Advanced settings

Most users should not need to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when track testing option selected under basic settings.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Show/Hide definitions

This shows or hides the worksheets where the data definitions are stored. For most users this can be ignored.

Show/Hide log

If aerotool crashes you can show the log and send that information to support@aerosensor.tech for technical support.

Operation

Here is just a quick description of these buttons

Load FIT files

Button opens a dialog to load in FIT files, either file based or aeroportal based, depending on Use cloud settings above.

Recalculate

Button recalculates data for all runs currently loaded.

Reset workbook

Deletes all currently loaded run data.

Check system

Checks the system is set up correctly to enable FIT files to be loaded.

Loading and viewing data

aeroworkbook

Loading and viewing data

Loading data

For each run you load into the excel tool, a separate worksheet will be created named Run_X where X is the number of the run, starting at 1 for the first one you load. It will also create a Summary worksheet showing data for all runs, and two graphs showing the CdA and power variation to your baseline.

File based system

Change use cloud in basic settings to false.
Click on Load FIT files.
Select one or more FIT files from the file system.

Each FIT file will be loaded in turn.

Aeroportal based system

1. Change use cloud in basic settings to true.
2. Click on Load FIT files.
3. Select one or more FIT file then click the Open
If the FIT file has not been loaded before, it will be saved onto your computer.

On windows files are saved to the following directory:
C:/Users/[UserName]/AppData\Roaming\AerosensorExcel

On Mac they are saved to the following directory: /Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Run analysis

There are a few steps to getting the best accuracy from your data.

On the worksheet for each run you can edit any of the cells highlighted yellow.

Select valid runs

Aeroworkbook will automatically mark runs as valid based on the speed tolerance criteria by putting an X in the Valid column of the Lap summary table, highlighted in yellow.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can whether to use auto cal for this specific run by selecting true or false under Auto cal in row 5.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters in the column marked Setting in device and also copied to Used for calibration when first loaded.

If any of these were not correct, or for example you are not using auto cal and want to manually change the Aero Cal value then can change it here.

Recalculate

Either click Recalculate sheet to recalculate data for the active run sheet, or click Recalculate on the Control worksheet to recalculate all runs. The data is recalculated in the run sheets and also updated in the Summary sheet.

Interpreting data

In the summary sheet you see a list of all of your runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the section “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
     $v =$ Speed (m/sec)

Histograms

On each run sheet histograms of headwind and wind yaw angle are shown for all of the laps marked as valid.

For each headwind bucket it shows the percentage of time spent with that level of headwind.
If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.
This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.
For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Editing data

aeroworkbook

Editing data

Creating sessions

Typically you will want to group runs together, for example by test, by creating sessions and then assigning runs to these sessions.

With Use Cloud set to True click on Load FIT files. Log in if requested.

Click on Edit sessions to open the Sessions dialog box.
Click on Create New Session to create a session.
Enter an appropriate name for the session then click Save.

This new session will now be available to assign to runs.

Assigning runs to a session

You can change the session associated with a run by editing the run information as described below. The sessions you created in the step above should all appear in the drop-down menu of the file details dialog.

Editing run information for a single run

With Use Cloud set to True click on Load FIT files. Log in if requested. The following form will show listing all of the runs available. Against each run is shown either Cloud or Local: If Local is shown then you have already downloaded the run locally.
Select a run by clicking on it then either click Edit or right-click on the run. It will open this form.
You can edit the Session, Run Description, Run notes and Used values which are the parameter values that aeroworkbook will use for calculations.
Click Save to update the information in the aeroportal database for that run.

Editing run information for multiple runs

Select multiple runs that you want to edit, then either click Edit or right-click on the runs to edit them.
The same File details form will open as before. Here you can only edit session, and Used values Values that are common for your runs will show in the dialog. Where values differ the associated field in the form will be blank.
Click Save to save these edited values for all runs.

Glossary

aeroworkbook

Glossary

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FIT file data

Fit files have 3 types of data. For each type there will be multiple variables such as power, speed etc.

Record

This is the time series data, recorded at 1Hz: one value per second.

Lap

One value per lap.

Session

One value for the entire FIT file.

Lap or Out-Back Summary Metrics

In the run data there are many columns. Some are self-explanatory but others are explained below.

Dist revs

Lap distance in wheel revolutions.

Av speed

Average speed over the lap = lap distance / lap time.

Yaw

Average wind yaw angle.

Abs Yaw

Average of the absolute yaw angle, where negative values are treated as positive.

Yaw SD

Standard deviation of the 1Hz yaw data over the lap. Indicator of how gusty the wind is.

Headwind

Headwind speed = wind speed resolved along direction of travel, minus wheel speed.

Headwind SD

Standard deviation of the 1Hz headwind data over the lap. Indicator of how gusty the wind is.

Pressure

Ambient air pressure.

Records

Number of 1Hz samples present in the lap.

Cal

Aero calibration value for the lap.

CdA

Lap CdA calcualted by aerosensor using the run parameters in the Garmin.

Head

Head position measured with aerobody.

Chest

Chest position measured with aerobody.

pXXXX

Average power values. Positive averages power in to the bike, negative is power out.

pRider

Average rider power.

pAero

Aero drag power

pGrav

Gravitational power (power used to propel up hill, or gained from going downhill).

pFric

Rolling resistance power

pKin

Kinetic power, i.e. if bike is accelerating then power is consumed by increase in kinetic energy.

pPdyn

Dynamic pressure power – this is basically average of speed x dynamic pressure. CdA = -pAero / pPdyn.

pXXXCor

_Cor suffix denotes values corrected for specified Used for calculation values under Run parameters.

CdAFinal

This is the CdA value corrected for specified run parameters and for the calculated aero calibration if Auto cal is set to true. If Auto cal is set to false then CdAFinal = CdACor.

Spd Mag Droprate

Aerosensor tries to detect where a magnet pass event is missed by the speed sensor. This is the rate of magnet pass “drops”. Should be zero.

Spd ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from speed sensor. Generally not an issue but useful for debugging. There will always be some dropped packets.

Pwr ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from power meter. Generally not an issue but useful for debugging. There will always be some dropped packets.

Run Data Metrics

These are the values shown near the top of the run worksheet.

Laps

Number of laps used for run calculation.

Av Speed

Average speed of all laps.

pRiderCor

Average rider power for all laps.

CdA Final

Final corrected CdA with calculated calibration applied if using Auto cal.

Cal Cor

Corrected calibration factor

CdAF+/-

Maximum lap CdA Final variation from the average, in m2.

CdAF+/-%

Maximum lap CdA Final variation from the average, as percentage of average.

Cal+/-%

Maximum Calibration factor variation from the average, as percentage of average.

Head

Average head position.

Chest

Average chest position.

Yaw

Average wind yaw angle, treating negative values as negative.

Abs Yaw

Average wind yaw angle, treating negative values as positive.

Yaw SD

Wind yaw angle standard deviation.

Headwind

Average headwind speed.

Hwind SD

Headwind standard deviation.

CdA Cor

Corrected CdA but if Auto Cal is used, without calibration factor applied.

FAQs

aeroworkbook

Frequently asked questions

Where are my aeroportal files stored locally?

Normally you shouldn’t need to go there, but in case you do:

Windows

On Microsoft Windows the files are saved locally to the following directory, where [UserName] is your username:

C:\Users\[username]\AppData\Roaming\AerosensorExcel

MacOS

On Mac the files are saved locally to the following directory, where [username] is your username:

/Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Can I work on aeroportal files offline?

Yes!

Make sure you download all the files you need while you are online:

Click on Load FIT files.
Select all the files you need which still have Cloud marked next to them in the list.
Click Download to save those files locally.

You can now load the files through the same Load FIT files dialog.

Note: You can only edit run details whilst online and logged into your aeroportal account.

Aeroportal

aeroportal

Overview

Aeroportal is our online platform designed to simplify your data analysis. You can automatically sync FIT files from Garmin Connect, making them accessible through Aeroportal itself, or our Excel Aeroworkbook.

Its main features are as follows:

Pair your Aeroportal and Garmin accounts for automatic importing and storing of FIT files generated with our ACS Connect IQ app.
Correct parameters.
Add descriptions and notes to each run.
Select valid laps.
Organise your runs into sessions.
Calculate out-back, lap and run average data.
Display histograms showing wind variation.

Important: Only FIT files recorded with our ACS Connect IQ app will be transferred to the Aeroportal server. All other FIT files will be ignored.

Quick start

For those in a rush, here is a brief overview of how to setup your Aeroportal account and view your runs:

After creating an account, pair your Aeroportal and Garmin accounts together, and request a Backfill in the settings page or sync some new runs through Garmin Connect.
Use the File Menu (button with three horizontal lines) to see a table of your available runs.
If desired, create Sessions to organise your runs by pressing the sessions tab in the file menu.
If required, you can change the data parameter values of runs by selecting them and and clicking the Edit button. You can also set their sessions here.
Select all runs you wish to view and click the View button.
Click on a Run in the run list on the left hand side, and select Valid laps in the Lap Summary table under the Laps tab, and click Save Laps & Recalc. Valid laps are the laps that will be used for the run calculation.
Final run data is shown in the Summary item in the run list.

Layout and Account Setup

aeroportal

Aeroportal Layout

The following screenshots show various components of the aeroportal webpage.

Analysis page:

File Menu:

Open Runs:

Aeroportal account

Registration

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Register here” and complete the registration form.
Check your email for a confirmation link and click it to verify.
You should now be able to login to the Aeroportal.

Resetting your password

If you have forgotten your password to log in to Aeroportal, you can request an email to reset it.

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Reset here” and type in the email address associated with your aeroportal account.
Check your email for a reset link and click it.
Type in your new password.
Log in with your new credentials.

Garmin account

Pairing Garmin Account

Login to portal.aerosensor.tech.
On the settings page, under Garmin Integration click the Register with Garmin button.
Log in to your Garmin Connect account when prompted. If you have multiple Garmin accounts ensure you are logged into the correct one.
Follow the on-screen instructions to complete the pairing process.

Unpairing Garmin account

To disconnect your Garmin account from Aeroportal:

Login to portal.aerosensor.tech
On the settings page, under Garmin Integration click the Deregister with Garmin
In the popup press Deregister

To disconnect your Garmin account from Aeroportal via Garmin Connect:

Log in to your Garmin Connect account.
Click your profile logo in the top-right corner, then select Account Settings.
In the left-hand menu, choose Account Information.
Under Aeroportal, click Disconnect.

Backfill (Importing historical data)

After you have paired you Aeroportal and Garmin accounts together, the backfill feature allows you to import FIT files uploaded to Garmin Connect before your Aeroportal and Garmin accounts were paired. Once logged into Aeroportal, go to the “Settings” page via button at top of screen.

Log in to the Aeroportal and navigate to Settings via the top menu.
Under Garmin Integration, find the Backfill Data button.
Use the date pickers to select a start and end date. Note: The selected date range must not overlap with dates already downloaded. If it does, unlink and relink the Aeroportal app to Garmin Connect before retrying.

Click “Request backfill data”. The files will download in the background.
To confirm the import, check the available files either in the Aeroportal file menu or the Excel Aeroworkbook
Note: it can take a few minutes for the files to be pulled across to our cloud servers.

Editing Data and Run Setup

aeroportal

Editing runs

Once you have paired your Garmin account and have some files available on our server, you can set persistent descriptions, notes, sessions and metrics for your runs.

Editing a single run

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Use the Pencil Icon to the right of a run to edit data for the corresponding run.
This will open a new menu which will allow you to edit the Session, Run Description, Run notes, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and will be available for use.

If you want to quickly set/edit a description for a run, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the run you want to edit.
Type your new description.
Click away from the Description to save it.

Editing multiple runs

Editing multiple runs at once is a convenient way to assign a session or change values for the selected runs.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select multiple runs by using the checkboxes on the left and clicking the Edit button to edit the selected runs (e.g. assigning a session to multiple runs).
This will open a new menu which will allow you to edit the Session, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and are available for use.

Deleting one or more runs

Sometimes you may want to delete a run, for example, if you backfilled and have multiple runs that are the same. Note: This is a permanent action and to get these runs back you will have to submit a backfill request with the appropriate dates. We also do not recommend deleting runs that were “Errors” during testing, as we will implement a “Hide Run” option in the future, that will allow your run numbering in sessions to stay consistent.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select one or more runs by using the checkboxes on the left and clicking the More button next to Edit and View.
Press the Delete selected button.
Press Yes on the popup.

Editing sessions

Sessions are a way to organise, and group runs.

Viewing/Editing your sessions

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
The table will now list all your sessions, including how many runs are currently assigned to a session.
Use the Create New button to create a new session and set its description.
Use the Pencil Icon on the right of a session to edit it.
You can assign runs to sessions as described in the section above.

If you want to quickly set/edit a description for a session, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the session you want to edit.
Type your new description.
Click away from the Description to save it.

Deleting a session

Sometimes you may want to delete a session. Note: This will NOT delete the runs associated with that session, but they will instead be set to not belonging to a session.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
Click the Pencil Icon to the right of a session to edit it.
Click the Delete session button.
Press Yes on the popup.

Setup before viewing runs.

Before viewing your available runs there are some settings you may want to check.

Run specific settings

These settings may be modified by following the steps above in “Editing runs”.

Basic run settings:

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Testing type

Either track or out-back. Note: Aeroportal automatically picks up what option you selected when starting the run on the Garmin device and sets it appropriately, but it can still be changed if needed.

Auto calibrate

Aeroportal calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Advanced Run Settings:

Most users should not have to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when the run is set to Testing Type: Track.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Device wide settings

These are settings that will be applied to all the runs you view. They are found in the Settings page accessible through the cog icon in the top right corner.

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Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Speed units

Select an option from either kph or mph.

Viewing Data

aeroportal

Viewing your runs

Once you have paired your Garmin account and have some files available on our server, you can view your runs. If needed, you can refer to the screenshots in Layout and Account Setup.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
If you have runs available, they will be displayed in the table.
Select all the runs you would like to view using the checkboxes on the left.
Press the View button on the top right.
After a couple of seconds, all runs will be opened and displayed.
By default, the Summary tab will be displayed which contains a table with information about all currently viewed runs, and charts may be viewed by pressing the corresponding tabs at the top.
You can view individual runs by selecting them from the list view on the left hand side.

Note: You can use the Group by Sessions slider to display runs based on session. You can also open all runs belonging to a session directly from the Sessions tab in the file menu.

Run analysis

There are a few steps to getting the best accuracy from your data.

Select valid runs

Aeroportal will automatically mark laps as valid based on the speed tolerance criteria by selecting the checkbox in the valid column in the Laps summary table.

The Laps summary table can be found by clicking on a run in the list view on the left, and clicking on the Laps tab at the top.
Under the Valid column, you can select/deselect laps to be marked as valid.
Once you are happy with your selection, press the Save Laps & Recalc button, to save your lap selection to our server and recalculate the run. This will also update information in the Summary for all viewed runs. Note: Next time you open this run in the aeroportal, it will be loaded with your valid lap configuration.

Note: If you would like to reset a runs valid laps to its defaults, you can press the Reset Valid Laps button.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can set whether to use auto cal for this specific run by selecting true or false under Auto cal by following the guidance in the section Editing Data and Run Setup.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters section of the Summary tab of an open run. “Default” marks the Setting in device and also copied to “Used” for calibration when first loaded.

If any of these were not correct, or for example you are not using Auto Cal and want to manually change the Aero Cal value then you can set it by following the instructions in “Editing a single run”.

Recalculate

When changing values such as Run Metrics, Auto Cal, Test Type etc, you can open the file menu, check that the runs you want to view are selected, and press View again. This will recalculate the files with your saved values, update individual runs and also update the Summary tab.

Interpreting data

In the summary tab you see a list of all of your viewed runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the column grouping “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
$v =$ Speed (m/sec)

Histograms

On each run in the main list of runs to the left, histograms of headwind and wind yaw angle are shown for all of the laps marked as valid, under the Charts tab on the top.

For each headwind bucket it shows the percentage of time spent with that level of headwind.

If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.

This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.

For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Aerosensor Lap Logger

aerosensor lap logger

Introduction

The Aerosensor Lap Logger is software that lets a coach monitor data from the ACS Connect IQ app trackside.

The Garmin device running the Connect IQ app transmits lap data continuously via an ANT dongle, enabling a connected computer to display and record results in real time. This immediate feedback helps coaches make quick, informed decisions before the rider leaves the track. The lap end data flow is as follows:

Aerosensor takes roughly 3 seconds to send lap end data after receiving lap trigger because of the lap averaging process.

Important notes

When testing multiple riders in the same session, only one Aerosensor should be powered on. The Aerodrome sends lap triggers to the first Aerosensor it detects after each lap, so having multiple sensors active can cause conflicts.
The Lap Logger receives data from all ACS apps in range, so only one Garmin running the ACS app should be used during testing. Multiple Garmins can confuse the logger and result in inaccurate data. The lap logger will warn you if it detects multiple Garmins running the ACS app.

Installation

Compatibility: The software currently runs on Windows only
Download: Available under the "Live lap viewer" section at: https://aerosensor.tech/pages/downloads
ANT+ Dongle Required: For example, the Garmin dongle: https://www.garmin.com/en-GB/p/10997
Optimal Reception: Use a 2m USB extension cable to place the dongle higher up for better signal quality.

Operation

Launch the Application
- From the Start menu, search for ANT_Lap_Logger or use the desktop shortcut. A main window will appear.

Choose a Save Location
- Click Browse and select a folder to store the log files.
Connect the Sensor
- Click Connect and confirm that “Sensor opened” appears.
- In the Messages window, if the ACS app is open on the Garmin, you should see incoming data packets.
- If no data appears, click Close then Open to reset the connection.
- Packet Details: The first byte is the packed ID, and each complete lap message has three packets starting with “0,” “4,” and “8,” ending with the lap number. Lap data only appears once all three packets have been received.
Start a Run
- Click Reset to clear previous data from the LapData grid.
- Enter the run description in the Description field (editable anytime before stopping the log).
- Click Start log to begin recording data.
Note that if there are laps already showing in the lap logger it will give you the option to delete them all. If you want to keep them simply click “No” and these previous laps will be recorded to your log file also.
Monitor Lap Data
- As each lap arrives, use the Flag checkbox to include or exclude laps. The session data displays the average of all flagged laps.

End the Session

Click Stop log to save the data and close the log file.

Access the Log File

Popout window

Click the open popout button in the main window to open a separate window with larger format text. This can be helpful if you need to see key data from a distance, for example if you as the coach want to stand by the start/finish line and shout out lap times to the rider.

Settings

Application settings can be edited from the File->Settings menu:

Number of laps to use for calibration:
Automatically apply average calibration
CSV file separator

Status indicators

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Connection

Closed: ANT USB device connection is not opened. Click “Open” under “Garmin connection”.
Not receiving: Connection to ANT USB device is open but no data is being received.
Receiving: Data is being received from the Garmin. Note you do not need good reception for the entire lap, only for a couple of seconds or so minimum.
“Multiple Garmins!”: Multiple Garmin bike computers running the ACS app are within range. Please turn off the ACS app on the Garmin not in use.

Latest lap: Lap number of most recent complete lap.
Lap data: Each lap requires 3 “packets” of data. These packets are sent 8 times in sequence.
Lap Status: When the Garmin is first turned out it sends packets with no data. These laps are marked as “Invalid”.

For any support queries, please email us at support@aerosensor.tech.

Aerodynamic basics

aerodynamics basics

What is aerodynamic drag?

Aerodynamic drag is the force of the air acting to slow down a cyclist moving through it.

It is made up of two major components – pressure drag and skin friction drag.

Pressure drag is related to the size and shape of the bike and rider. As you cycle forwards you hit air particles out of the way. These are compressed on impact but then space out as they pass over and past you – the difference between these two air pressures is pressure drag. This is why getting into an aerodynamic position and allowing the oncoming air to flow smoothly around you, reduces your overall aerodynamic drag and makes it easier to cycle.
Skin friction is related to the roughness or texture of the surface on the bike and rider, a smooth (laminar) surface allows air particles to have consistent trajectories (pathlines). A rough (turbulent) surface causes irregular pathlines. Something to note however is surface roughness can be used to keep flow attached longer (for example a textured should on a skinsuit) which increases skin friction drag, but reduces pressure drag (of which is a larger component and therefore can reduce overall drag.

How do we measure aerodynamic drag?

There are five forces acting on a cyclist. Aerosensor works by measuring or estimating forces (or power) from the rider (F_R), kinetic (F_K), gravitational (F_G) and friction (F_F) to find the fifth, aerodynamic drag (F_D).

The sum of these sources (positive) and sinks (negative) plus the aerodynamic drag (sink) must equal zero:

$F_{R} \pm F_{K} \pm F_{G}-F_{F}-F_{D}=0$

Aerodynamic drag is comprised of the product of dynamic pressure (p_Dyn, directly measured by Aerosensor), coefficient of drag (C_d, a constant for a given body position/setup) and frontal area (A). In cycling, the coefficient of drag and frontal area are commonly combined as the term CdA:

$F_{D} = p_{\text{Dyn}} \times C_{d}A$

Combining these two equations gives you a relationship between CdA and the other bike forces:

$C_{d}A = \frac{{F_{R} \pm F_{K} \pm F_{G} – F_{F}}}{{p_{\text{Dyn}}}}$

This is what your Aerosensor calculates in real-time!

Why is aerodynamic drag important?

Although aerodynamic drag increases with speed, friction does not – so at high speeds aerodynamic drag dominates.

Above you can see that at 5kph just 10% of your power goes into overcoming aerodynamic drag, and at 40kph this increases to over 80% – ie 80% of your power is used only to push you through the air.

Say you’re taking part in a flat 40km TT, how can reducing your CdA (and therefore aerodynamic drag) affect your race time?

In this example, reducing your CdA by around 10% can save over 1 minute and 30 seconds. The great news about aerodynamic testing is that you can make huge strides in making yourself faster and/or saving more energy for when it matters.

Troubleshooting

Aerosensor

Aerosensor won’t turn on

We have a known issue where Aerosensor can become unresponsive.

Make sure device has charge by plugging into USB-C.
Press reset button. You can find instructions on where to find it in the quickstart.

In addition, our device works on a standard 5V power supply. Some laptop/phone charges are “smart chargers” that communicate with device to charge at a higher voltage. These just flat out don’t work, so please try the following:

Try a different power source. A computer USB port is usually a safe bet.
Try a different USB cable, just in case that is the problem. Rare but it has happened that the USB cable isn’t suitable.

If the LED doesn’t come on after this, please reach out to our support team.

CdA not showing (invalid or zero)

It is likely that Aerosensor is not correctly paired to your ANT+ sensors.

BLE/ANT+ sensors transmit as both BLE and ANT+ separately. You may have paired to the BLE sensor. In the Garmin go to the sensor, and check that you are paired to the ANT+ sensor.
Check that the ANT+ power meter AND EITHER speed OR speed and cadence sensor is paired properly. Ensure the sensors are on by rotating pedals/crank/wheel then check pass-pairing (in CIQ app go to Connections->Pass Pairing). When properly paired the SPD and PWR icons in the top right hand corner of the CIQ app will show green.

CdA doesn’t match expectation

There are a few reasons Aerosensor may report an incorrect CdA value.

Check that you have entered an appropriate Aero Calibration factor in the CIQ app (Aerosensor settings->Parameters->Edit Parameters). For instructions on how to get this value see the quickstart guide.
Make sure you have calibrated the power meter.
Make sure that other Aerosensor parameters (in particular Total Mass, Wheel Circumference, Power meter scaling, Reference Crr) are correct.
If using a pedal based power meter, ensure that the crank length is set correctly in the Garmin Power Meter sensor settings.

Aerosensor won’t update

If Aerosensor is not able to connect to the aerosensor updater then it is likely the USB-C cable is power only, not power + data. Try a different cable.

We have also noticed that USB-C to USB-C chargers don’t work for updater for this reason.

Aerobody

Aerodrome

Too many laps

If, when using Aerodrome, more laps are shown than expected, it is likely that you are experiencing drop-outs in the speed sensor.

This means that Aerosensor sporadically auto-laps independent of Aerodrome.

Try moving your magnet speed sensor to the front wheel, this should fix the issue.

Tutorial Videos

This area is currently in construction – stay tuned for more videos soon!

Aerosensor Setup

In this video we show you how to setup our cycling aerodynamic drag measurement device, Aerosensor: From unboxing through to testing the setup on a turbo trainer.

Aerobody Setup

In this video we show you how to set Aerobody up on the bike, and use both the ACS Connect IQ (CIQ) app, and the Aerobody Datafield to set it up and view the data.

Excel Analysis Tool

Find out how to use our Aerosensor Excel Analysis Tool, enabling you to get the most of your aerodynamic cycling data and make conclusions about your testing quickly and with confidence.

This video takes you from installation on your Windows or Mac computers, through to loading, editing, and analysing the data.

Downloads

Demo FIT Files

Out-back FIT file

Download demo FIT file to try out-back analysis using our excel tool and other platforms.

Updated 24th March 2025.

Velodrome FIT files

Demo FIT files. See notes text file for more information.

Updated 24th March 2025.

Garmin Connect IQ Apps & Datafields

ACS App

Aerosensor Cycling System app lets you get the most from our unique system of aerodynamic development devices.

Aerobody Datafield

View your body position as you ride, in the context of your favourite data screens with a datafield dedicated to Aerobody.

Aeroworkbook

aeroworkbook for Windows and Mac

Import Aerosensor FIT files directly to excel, and perform basic out-back and velodrome analysis.

V5.1.9 updated 18th November 2025.

Trackside Lap Logger

Aerosensor lap logger

View and log lap data trackside on a Windows computer.

V1.4.1, updated 13th March 2025.

ANT+ dongle driver

Windows driver for ANT+ USB dongle.

Firmware Updater

Aerosensor Updater for Windows

Update your aerosensor and aerodrome firmware to the latest version using a Windows laptop or desktop computer.

Note: For updating, a USB-A to USB-C cable to connect the device to your laptop/computer is required. If your laptop/computer only has USB-C ports then a USB-C to USB-A adaptor is needed.

Please note that updates are only available for Aerosensor and Aerodrome.

Updated 27th September 2024 to V1.11

Aerosensor Updater for macOS

Update your aerosensor and aerodrome firmware to the latest version using an Apple Mac laptop or desktop computer.

Note: For updating, a USB-A to USB-C cable to connect the device to your Mac is required. If your Mac only has USB-C ports then a USB-C to USB-A adaptor is needed.

A macOS version of 12.4 or higher is required.

Please note that updates are only available for Aerosensor and Aerodrome.

Updated 31st October 2025 to V1.16

WKO Charts

WKO CHART

Chart layout for viewing Aerosensor data in WKO V4 or V5.

(01.11.23 Update)

Note that WKO does not show the lap or session data, only the record data, which is the time history.

CAD Files

The CAD files are provided for free use; however, users assume all associated risks. Aerosensor disclaims any responsibility for loss or injury resulting from the use of these files.

Current Aerosensor stay

Includes stay and fairing, plus assembly.

Updated Aerosensor stay

One-piece stay released February 2024.

Pressure Scanner

AeroDAQ for Windows

Configure and record data from your SC-01 Pressure Scanner with our Windows AeroDAQ software.

Updated 5th December 2025 to V1.0

SC-01 User Manual

Hardware, Software and User Programming Manual for our SC-01 Pressure Scanners.

Updated 5th December 2025 to V1.0

SC-01 Specification

Specification sheet for our SC-01 Pressure Scanners.

Updated 5th December 2025 to V1.0

Quickstart

What follows outlines the basic setup of Aerosensor. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerosensor Setup

Install Aerosensor securely, level, and centred on the bike using a go-pro mount.
Pair your power meter speed sensor to Garmin. We recommend dual sided power meter, and magnet based speed sensor.
Calibrate power meter in Garmin, and set crank length if necessary.
Open ACS CIQ app on your Garmin bike computer.
Choose test type:
1. Road: for general road cycling.
2. Out and back: for cycling out and back along a stretch of road.
3. Velodrome trackless: for velodrome use without Aerodrome lap trigger.
4. Velodrome tracked: for velodrome use with Aerodrome lap trigger.
Connect Aerosensor to CIQ app.
1. Turn on Aerosensor. It should connect automatically. If not:
2. Menu > Connections > Aerosensor.
3. Wait for CIQ app to find device, then click on it to connect.
Input key parameters Menu > Aerosensor Settings > Parameters > Edit Parameters. Most important parameters to set are:
1. Aero device calibration: Start with a value of 1.4.
2. Total mass (your total mass i.e. you + bike + clothing)
3. Wheel circumference You can get from speed sensor info in Garmin, or roll out wheel and measure distance on ground.
4. Power meter scaling This accounts for drive train losses. Typically use 0.98 for all but hub based PMs
5. CTF calibration offset Only necessary if using an SRM PM7 or earlier Power meter. This is the value reported when you calibrate your power meter on the Garmin.
Be sure to “Push Parameters” after exiting this menu to save any changes.
Check connections, and start activity
1. Make sure your power meter and speed sensor are on, by rotating wheel and pedals.
2. If paired then “PWR” and “SPD” icons in top right go green. If not see ACS instructions.
Start activity

That’s it! You are now ready to go aero testing. For accurate results be sure to calibrate your aerosensor every time you change bike or make a substantial change in your position. Don’t worry, you can do this at the same time as testing and post-correct your data, so no specific runs are necessary. See next section.

Calibration

The air “sees” you coming towards it due to high pressure build up ahead of you. For this reason the air at Aerosensor’s location on your bike is slower than freestream. We need to correct for this.

Perform at least two out/backs or 4 laps of velodrome. Be sure to start activity before starting this, and stop activity at the end.
Select valid laps. Go to page 9 of the CIQ app, press menu, then either press up or down arrows or swipe up or down to select laps. Press menu again to toggle valid (“X”) or invalid (no “X”).
Read the new cal value (“New_Cal”). You can either see this at the top of the lap page, or on page 10.
You can post-correct your CdA values by dividing them by this value. This can also be done in aeroworkbook or aeroportal. See relevant sections under “Data analysis”.
CdA_corrected = CdA_reported * Old_cal/ New_cal
Enter new “Aero device calibration” in Aerosensor Settings.
Menu > Aerosensor Settings > Parameters > Edit Parameters.

Aero testing guidance

Reliable aerodynamic testing is reliant on good testing protocols, focus on the following:

CdA data is only as accurate as the inputs. Make sure you check Aerosensor’s settings in the ACS app before every test.
Always calibrate power sensor before starting testing, and ideally before each set of laps or out-backs. Small calibration offsets can result in a big error in CdA measurement.
Always start and end your test block with a baseline repeat.
Try to maintain a constant speed through each run.
For out and back testing we recommend a stretch between 600 and 1000m.
The more out and backs you do, the better the repeatability will be.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Introduction

aerosensor calibration

Introduction

What’s the problem?

As air approaches a cyclist, it slows down due to the build-up of high pressure in front of the bike and rider.
The CFD image below (from this site) shows air speed around a rider in three positions. We’ve added a red arrow to mark the typical Aerosensor location.

You can see:

Rider position changes how much the flow slows down.
In some cases, the slowdown begins well upstream of the bike.

Our own wind tunnel tests confirm this effect (figure 2). Even one metre in front of the bike, air speed is still reduced by 2–3%. Unfortunately, there’s no practical way to mount a sensor far enough forward to avoid this.

This isn’t unique to Aerosensor – it’s just physics. All on-bike aerodynamic devices face the same challenge. The best we can do is minimise the effect by placing the sensor as far forward as possible, then correct for it through calibration.

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What’s the solution?

We overcome this problem by calibrating the sensor.

In still air, road speed and true airspeed are the same. By comparing road speed to the sensor’s measured airspeed, we can calculate a calibration factor that scales the reading back to freestream conditions.

As long as the rider position and setup remain unchanged, this calibration factor will also stay constant.

Section 1

Articles

Article 1.1

Section 2

Article 2.1

Article 1.2

Article 1.1

Article 2.1

Aerosensor

Articles

Quickstart

What follows outlines the basic setup of Aerosensor. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerosensor Setup

Install Aerosensor securely, level, and centred on the bike using a go-pro mount.
Pair your power meter speed sensor to Garmin. We recommend dual sided power meter, and magnet based speed sensor.
Calibrate power meter in Garmin, and set crank length if necessary.
Open ACS CIQ app on your Garmin bike computer.
Choose test type:
1. Road: for general road cycling.
2. Out and back: for cycling out and back along a stretch of road.
3. Velodrome trackless: for velodrome use without Aerodrome lap trigger.
4. Velodrome tracked: for velodrome use with Aerodrome lap trigger.
Connect Aerosensor to CIQ app.
1. Turn on Aerosensor. It should connect automatically. If not:
2. Menu > Connections > Aerosensor.
3. Wait for CIQ app to find device, then click on it to connect.
Input key parameters Menu > Aerosensor Settings > Parameters > Edit Parameters. Most important parameters to set are:
1. Aero device calibration: Start with a value of 1.4.
2. Total mass (your total mass i.e. you + bike + clothing)
3. Wheel circumference You can get from speed sensor info in Garmin, or roll out wheel and measure distance on ground.
4. Power meter scaling This accounts for drive train losses. Typically use 0.98 for all but hub based PMs
5. CTF calibration offset Only necessary if using an SRM PM7 or earlier Power meter. This is the value reported when you calibrate your power meter on the Garmin.
Be sure to “Push Parameters” after exiting this menu to save any changes.
Check connections, and start activity
1. Make sure your power meter and speed sensor are on, by rotating wheel and pedals.
2. If paired then “PWR” and “SPD” icons in top right go green. If not see ACS instructions.
Start activity

That’s it! You are now ready to go aero testing. For accurate results be sure to calibrate your aerosensor every time you change bike or make a substantial change in your position. Don’t worry, you can do this at the same time as testing and post-correct your data, so no specific runs are necessary. See next section.

Calibration

The air “sees” you coming towards it due to high pressure build up ahead of you. For this reason the air at Aerosensor’s location on your bike is slower than freestream. We need to correct for this.

Perform at least two out/backs or 4 laps of velodrome. Be sure to start activity before starting this, and stop activity at the end.
Select valid laps. Go to page 9 of the CIQ app, press menu, then either press up or down arrows or swipe up or down to select laps. Press menu again to toggle valid (“X”) or invalid (no “X”).
Read the new cal value (“New_Cal”). You can either see this at the top of the lap page, or on page 10.
You can post-correct your CdA values by dividing them by this value. This can also be done in aeroworkbook or aeroportal. See relevant sections under “Data analysis”.
CdA_corrected = CdA_reported * Old_cal/ New_cal
Enter new “Aero device calibration” in Aerosensor Settings.
Menu > Aerosensor Settings > Parameters > Edit Parameters.

Aero testing guidance

Reliable aerodynamic testing is reliant on good testing protocols, focus on the following:

CdA data is only as accurate as the inputs. Make sure you check Aerosensor’s settings in the ACS app before every test.
Always calibrate power sensor before starting testing, and ideally before each set of laps or out-backs. Small calibration offsets can result in a big error in CdA measurement.
Always start and end your test block with a baseline repeat.
Try to maintain a constant speed through each run.
For out and back testing we recommend a stretch between 600 and 1000m.
The more out and backs you do, the better the repeatability will be.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Important notes & prerequisites

Important notes

Aerosensor is designed for outdoor paved roads or velodrome use in dry conditions and is therefore not suitable for wet conditions.

The device is not waterproof as it has holes to allow pressure measurement.

Aerosensor must be removed in wet conditions. If you think it will rain whilst you are out riding or the road may be wet in places then take a 3mm hex key with you so you can remove the device and put it in your jersey pocket for the rest of your ride.

Aerosensor will vibrate on rough paved roads. This has no negative impact on measurement quality. However if excessive vibrations occur, or if Aerosensor pitches down after use, please check the got-pro mount screw was sufficiently tight.

Clean Aerosensor with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerosensor requires an ANT+ power and either bike speed or bike speed + cadence sensor. It also requires a Garmin cycling computer.

Bike Computer

Currently to use the ACS you will need a Garmin bike computer that can run Garmin Connect IQ applications at a minimum of SDK 3.1.0. A full list of compatible devices is available on the link below – be sure to check that the device has the “A” symbol, meaning apps.

Note Edge 130/130 plus computers are NOT compatible as they do not allow you to run the CIQ app.

https://developer.garmin.com/connect-iq/compatible-devices/

We will make data fields in the future, allowing you to see data in the standard Garmin context, and also on the Edge 130.

Power Meter (PWR)

Aerosensor requires a quality power meter. Single sided pedal-based power meters are not sufficiently accurate for good aerodynamic data. Remember that the aero data you get will only be as accurate as the power meter used.

Speed (SPD) or Speed/Cadence (BSC) Sensor

For the best accuracy we highly recommend a magnet-based speed sensor. Hub mounted speed sensors or GPS based speed sensors do not have the time resolution necessary for high quality aerodynamic data.

Device mounts

Aerosensor has been designed to work on a variety of different bike bar types, notably the following:

Drop handlebars – usually standard on road bikes and track bikes.
Clip-on time-trial (TT) bars – additions to road and track bikes.
Integrated TT handlebar/cockpit – mostly seen on TT and triathlon specific bikes.

A go-pro mount is required to install Aerosensor – for example one underneath a bike computer mount (sold separately, available on our website in Accessories).

Whilst Aerosensor can be used on most bike setups, there will be some bar variants that may be trickier to setup. Please do not hesitate to contact us at hello@Aerosensor.tech with any questions or for advice on how to best mount onto your bike.

Device basics

Specifications

Dimensions (H x W x D)	135 x 57 x 85mm
Mass	66g
Battery Life	57 hours
Wind speed resolution	+/- 0.1%
Wind angle resolution	+/- 0.1°
Altitude resolution	+/- 10cm

Layout

LED
Power button
Reset button
USB-C bung & charging port
Stem
Height/yaw adjustment screw
Go-pro mount

Button functions

Power button:
- Press and release to turn on.
- Press and hold until LED turns off then release to shut down.
- Press and hold, push reset button, then release for full factory reset. This resets the internal settings used to calculate CdA.
Reset button:
- To be used in case the device becomes unresponsive. Resets device without erasing settings.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Aqua	Normal	On	Unplugged	Normal
Red	Normal	On	Unplugged	Low
Amber	Slow	Off	Plugged in	Charging
Amber	Solid	On	Plugged in	Charging
Green	Slow	Off	Plugged in	Charged
Green	Solid	On	Plugged in	Charged

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Installation

Use the go-pro mount itself to adjust pitch, then the yaw by loosening the height/yaw screw on Aerosensor’s stem (height adjuster) and rotating the unit.

Do not use the aerosensor base to pivot, this can cause damage to the stem.

When installing, it is important to have Aerosensor as far forward and low as possible that the stem allows to minimise influence of rider position.

The base must be at least 20mm above the front wheel.
It should be centred on the bike and facing forwards. Use the front wheel as a reference for yaw alignment.
Aerosensor should be level – use a horizontal object to the side of the bike (like floor markings), and visually align the bottom of Aerosensor with the horizontal line. An example is shown below, where a horizontal line on the wall is used. Note that the device is tolerant to pitch misalignment within +/-5°.

CIQ App

Aerosensor Connection

Make sure that Aerosensor is switched on.

1. Press the menu button on the Garmin head unit.

2. Select “Connections” -> “Aerosensor”.

3. Select the device you want to connect to. Note: it is worth keeping a note of the Device ID for your Aerosensor and Aerobody for your records, especially if you are a coach and have multiple devices for your riders.

Pass-pairing

Pass-pairing is where ACS transmits the power meter and speed sensor ANT+ connection details to Aerosensor, allowing it to connect to them directly.

For this to work the Garmin unit should already be paired with the ANT+ sensors you are using.

Note that Aerosensor requires a power meter (PWR) AND EITHER a speed sensor (SPD) OR speed + cadence sensor (BSC).

The CIQ app should automatically pass on the sensor connections to Aerosensor. In case this does not work, or you have multiple sensors on the bike, follow these steps:

Ensure that a power meter and speed sensor are installed on the bike and paired with the Garmin. Make sure they are on by rotating the wheel and/or pedals/crank, depending on the power meter.
In the ACS menu, select “Connections”->”Pass pair” which will bring up the following screen:

3. Either select the devices individually or select the bottom “Enter to sync” button in purple above. After a short period, the status bar at the bottom of the screen should go green to show Aerosensor matches the Garmin device. Aerosensor connection status icons should go from red to green.

Aerosensor Parameters

To accurately calculate aerodynamic drag, Aerosensor requires some information about you and your bike:

Aero device calibration: This accounts for the fact that the wind slows as it approaches the bike, so the wind speed measured by Aerosensor is always slower than the air far upstream of the bike. Start with a value of 1.4. Typically we see values beweeen 1.1 and 1.45. See ‘Quickstart’ section for more information.
Total mass (kg): includes rider + bike + all accessories used whilst riding with Aerosensor.
Wheel Circumference (mm). If unknown, you can go into the speed sensor settings on the Garmin and you will find the wheel circumference in there once you have ridden far enough for the Garmin to calibrate against GPS.
Power meter scaling: Default value is 1.0. If using pedals or crank we need to account for drivetrain losses. A typical value would be 0.98, i.e. 2% drivetrain loss.
CTF calibration offset: Used for CTF power meters.
Time av period: This is the time period used by Aerosensor to average the CdA value, default is 30 seconds.
Reference Crr: Rolling resistance coefficient (used if known), default 0.004. For an indoor velodrome you should use 0.002 (half the road value). You can find typical crr values for a range of tyres at https://www.bicyclerollingresistance.com/
Valid speed min: minimum speed (kph) for valid CdA automatic lapping. The CdA calculation is started when you go above this speed, and stopped when you slow down below this speed. The device automatically creates laps for each CdA measurement period.

Editing Parameters:

It is important you check these frequently, especially total mass and wheel circumference if changing between bikes for example.

Velodrome testing – Track layout

When Aerosensor is in track calculation mode it uses lap distance and speed to calculate lean angle to compensate for centre of gravity location. This only works when Aerodrome is being used. A typical track layout is shown below, of which you can input the track measurements by editing parameters directly in the CIQ app.

You can measure the track by measuring relative distance of corner start and end, using the distance markers along the track. This does not need to be very accurate – within a few meters is fine.

Measuring the track:

Measure the distance from the tapeswitch location to the start and end of each corner.
Use these to calculate the total distance of the two straight sections.
Corner length = track length – total straight lengths
Corner radius = corner length / pi
Transition length is the distance it takes for the rider to transition from the straight to the corner. Typical value is 10m.

Example:

Total track length = 250m.
C1 start = 10m
C1 end = 95m
C2 start = 135m
C2 end = 220m
Corner length = C1 end – C1 start – transition= 95 – 10 – 10 = 75m
Corner radius = 75/pi = 23.9m

Editing Parameters:

Velodrome testing – Calculation mode

At the velodrome Aerosensor can ignore the barometer, since elevation is roughly constant, and should use the track map. If the track map is not known, or Aerodrome is not available, you can use the trackless mode. To use Velodrome mode:

Go to Menu-> Aerosensor Settings->Calculation Mode.
Select the model you require:
1. Road
  For road riding.
2. Velodrome Trackless
  Assumes constant elevation but ignores track layout. This is for when you are not using a lap trigger (Aerodrome) or the track layout is unknown.
3. Velodrome Tracked
  Assumes constant elevation AND uses the track layout. This is for when you are using Aerodrome and know the track layout, as entered in ‘Aerosensor Settings->Track’.
Wait until the mode changes as required, in the menu heading.

Screen sequence shown below:

Aerosensor demo mode

This is for diagnostic purposes and can generally be ignored.

Aerosensor information

Go to Menu -> Aerosensor settings -> about

Here you can see information about your Aerosensor device, including battery level, firmware version and serial number. Battery voltage is also included as it is useful for diagnostic purposes.

Calibration

aerosensor calibration

For those in a hurry

No time to read the details? Here’s the short version:

Why calibrate?
Air slows down ahead of the bike, so Aerosensor’s dynamic pressure reading must be scaled up. This is called Aero Device Calibration in the CIQ app, or simply Aero Calibration or Cal in Aeroportal and Aeroworkbook.
What affects calibration?
Bike setup, rider position, sensor location – even helmet choice can make a small difference.
How is it done?
A calibration is calculated for every out-and-back run or lap of the velodrome, assuming zero average headwind.
What affects calibration accuracy?
Since we assume zero average headwind anything affecting the wind consistency will affect this. Wind variability (shown as Hwind SD – headwind standard deviation in particular) will degrade accuracy.
How accurate does it need to be?
Keep the CIQ app calibration factor within 5% of the measured value:
- For out-and-back tests, this is critical because it also affects altitude correction.
- For velodrome tests, this is less critical. Since altitude is not used (assumed to be constant) calibration can be corrected perfectly afterwards.
How do I use it in post-processing?
Both Aeroportal and Aeroworkbook offer Auto Cal, which applies the correct factor automatically. They also show:
- 🟢 Green: repeatable calibration, stable wind → Auto Cal can be used confidently.
- 🟠 Orange: some variability → check baseline repeatability; only use Auto Cal for smaller changes (<2%).
- 🔴 Red: inconsistent data → Auto Cal not valid; only test changes that don’t affect calibration, with a constant calibration.
Why does this matter?
All aero devices require calibration, even if others hide it. Aerosensor gives you full visibility and control, so you can trust the results based on what you saw and tested. It’s a little extra work, but it leads to more reliable data.

Introduction

aerosensor calibration

Introduction

What’s the problem?

As air approaches a cyclist, it slows down due to the build-up of high pressure in front of the bike and rider.
The CFD image below (from this site) shows air speed around a rider in three positions. We’ve added a red arrow to mark the typical Aerosensor location.

You can see:

Rider position changes how much the flow slows down.
In some cases, the slowdown begins well upstream of the bike.

Our own wind tunnel tests confirm this effect (figure 2). Even one metre in front of the bike, air speed is still reduced by 2–3%. Unfortunately, there’s no practical way to mount a sensor far enough forward to avoid this.

This isn’t unique to Aerosensor – it’s just physics. All on-bike aerodynamic devices face the same challenge. The best we can do is minimise the effect by placing the sensor as far forward as possible, then correct for it through calibration.

.centered { text-align: center; }

What’s the solution?

We overcome this problem by calibrating the sensor.

In still air, road speed and true airspeed are the same. By comparing road speed to the sensor’s measured airspeed, we can calculate a calibration factor that scales the reading back to freestream conditions.

As long as the rider position and setup remain unchanged, this calibration factor will also stay constant.

Technical detail

aerosensor calibration

.centered { text-align: center; }

Technical detail (optional bedtime reading..)

If you’re mainly interested in how to use Aerosensor, you can skip this section. The details here are for those who want to understand the physics behind the calibration process.

Aerodynamic basics

Aerodynamic force generally scales with dynamic pressure - the pressure increase you’d get if moving air was brought to rest.

The formula for this is:

$p_{dyn}=\frac{1}{2}\rho V^2$

Where:

$p_{dyn}$ = dynamic pressure (Pa)
$\rho$ = air density
$V$ = Air speed.

Since drag force is proportional to dynamic pressure, we can calculate a drag coefficient, $C_dA$ :

$CdA\ =\ \frac{Drag}{p_{dyn}}$

Dynamic pressure is just the difference between total pressure (the pressure measured by the little tube in the centre of aerosensor) and the static pressure (ambient pressure):

$pDyn\ =\ p_T-p_S$

Measuing dynamic pressure

Aerosensor cannot measure the true static pressure because it sits close to the bike, where the flow is already slowing down. Instead it measures a slightly different static pressure, $p_{aero}$ .

From aerodynamic theory the difference can be expressed as the pressure coefficient, $Cp_{aero}$ .

$C_{p_{aero}}=\frac{p_{aero}-p_s}{p_T-p_s}$

What aerosensor actually measures is $dp$ :

$dp=p_T-p_{aero}$

Expanding this and substituting in $C_{p_{aero}}$ :

$dp=(p_T-p_S)-(p_{aero}-p_S)$

$dp=p_{dyn}-C_{p_{aero}} p_{dyn}$

$dp=(1-C_{p_{aero}}) p_{dyn}$

Rearranging:

$p_{dyn}=\frac{dp}{1-C_{p_{aero}}}$

Aero device calibration

This leads to the aero device calibration, $cal$ :

$cal=\frac{1}{1-C_{p_{aero}}}$

So the corrected dynamic pressure is calculated by:

$p_{dyn}=cal\times dp$

How it's calculated in practice

In the real world, where there may be wind, calibration is derived from an out-back run or a single lap of a closed circuit, based on the assumption that the average wind is zero.

Aerosensor calculates:

The average measured pressure $dp$ .
The average dynamic pressure inferred from wheel speed.

Dividing (2) by (1) gives you the calibration factor for that run.

Post-correcting for updated calibration factor

CdA can be post-corrected for calibration factor as follows:

${CdA}_{new}=\ {CdA}_{old}\times\frac{{cal}_{old}}{{cal}_{new}}$

Where:

$CdA_{old}$ = CdA reported by Aerosensor.
$cal_{old}$ = Calibration factor entered in settings in CIQ app.
$cal_{new}$ = new calibration factor you want to apply.
$CdA_{new}$ = corrected CdA.

Both Aeroportal and Aeroworkbook do this automatically when you change the calibration factor.

However, this correction is not perfect in every case. To calculate altitude, we need accurate dynamic pressure. On velodromes, altitude is ignored, so calibration can be corrected perfectly afterwards. On out-and-backs, large errors in calibration will reduce CdA accuracy.

For example:

On an out-back run, a 10% error in calibration, combined with a 25% variation in speed across the lap, results in about a 1.5% error in CdA.
If speed were perfectly constant through the lap, the error would be zero.

Keeping your speed consistent between runs reduces the impact of calibration error on your results.

Recommended protocol

aerosensor calibration

Recommended Protocol

General approach: Run a baseline first, update your calibration factor, then continue with your tests.

Velodrome: At least 1500 m (≈6 good laps of a 250 m track).
Out-back: At least 3 out-backs, each 600–1000m in length.

You can select valid laps in the CIQ app and read off the average calibration, or use Aeroportal / Aeroworkbook to do the same.

There are a few things to bear in mind based on test type.

Indoor Velodrome

Calibration is easiest on an indoor Velodrome because it there is no wind. A couple of points to watch out for:

Ride alone: Other riders disturb the air, effectively giving you a false tailwind.
Limit calibration laps: Only use the first ~5 laps for calibration (set under Advanced settings → Max calibration laps in the Aeroworkbook and under Edit run in Aeroportal). After that, you start creating your own “tailwind.” Think of the velodrome as a giant cup of tea and yourself as the spoon — circulation builds gradually, but eventually it affects your data.

Outdoor Velodrome

Outdoors you don’t generate your own tailwind, but you will almost always encounter some ambient wind.

Collect at least 1500m of data (≈6 laps of a 250 m track).
More laps generally improve reliability.

Out-Back testing

Two main issues affect out-back calibration:

Traffic: Passing cars, motorbikes, or cyclists disturb the air and create headwinds or tailwinds. The more traffic, the less reliable your calibration.
Consistency of start/end point: Local features (trees, buildings, hedges) influence wind patterns. If your “out” and “back” sections don’t overlap exactly, calibration accuracy suffers.

Best practice:

Choose quiet roads and times with minimal traffic.
Keep start/stop points, acceleration, and deceleration as consistent as possible.
The more consistent your testing, the more consistent the results.

Important notes & prerequisites

Important notes

Aerosensor is designed for outdoor paved roads or velodrome use in dry conditions and is therefore not suitable for wet conditions.

The device is not waterproof as it has holes to allow pressure measurement.

Aerosensor must be removed in wet conditions. If you think it will rain whilst you are out riding or the road may be wet in places then take a 3mm hex key with you so you can remove the device and put it in your jersey pocket for the rest of your ride.

Aerosensor will vibrate on rough paved roads. This has no negative impact on measurement quality. However if excessive vibrations occur, or if Aerosensor pitches down after use, please check the got-pro mount screw was sufficiently tight.

Clean Aerosensor with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerosensor requires an ANT+ power and either bike speed or bike speed + cadence sensor. It also requires a Garmin cycling computer.

Bike Computer

Currently to use the ACS you will need a Garmin bike computer that can run Garmin Connect IQ applications at a minimum of SDK 3.1.0. A full list of compatible devices is available on the link below – be sure to check that the device has the “A” symbol, meaning apps.

Note Edge 130/130 plus computers are NOT compatible as they do not allow you to run the CIQ app.

https://developer.garmin.com/connect-iq/compatible-devices/

We will make data fields in the future, allowing you to see data in the standard Garmin context, and also on the Edge 130.

Power Meter (PWR)

Aerosensor requires a quality power meter. Single sided pedal-based power meters are not sufficiently accurate for good aerodynamic data. Remember that the aero data you get will only be as accurate as the power meter used.

Speed (SPD) or Speed/Cadence (BSC) Sensor

For the best accuracy we highly recommend a magnet-based speed sensor. Hub mounted speed sensors or GPS based speed sensors do not have the time resolution necessary for high quality aerodynamic data.

Device mounts

Aerosensor has been designed to work on a variety of different bike bar types, notably the following:

Drop handlebars – usually standard on road bikes and track bikes.
Clip-on time-trial (TT) bars – additions to road and track bikes.
Integrated TT handlebar/cockpit – mostly seen on TT and triathlon specific bikes.

A go-pro mount is required to install Aerosensor – for example one underneath a bike computer mount (sold separately, available on our website in Accessories).

Whilst Aerosensor can be used on most bike setups, there will be some bar variants that may be trickier to setup. Please do not hesitate to contact us at hello@Aerosensor.tech with any questions or for advice on how to best mount onto your bike.

Technical detail

aerosensor calibration

.centered { text-align: center; }

Technical detail (optional bedtime reading..)

If you’re mainly interested in how to use Aerosensor, you can skip this section. The details here are for those who want to understand the physics behind the calibration process.

Aerodynamic basics

Aerodynamic force generally scales with dynamic pressure - the pressure increase you’d get if moving air was brought to rest.

The formula for this is:

$p_{dyn}=\frac{1}{2}\rho V^2$

Where:

$p_{dyn}$ = dynamic pressure (Pa)
$\rho$ = air density
$V$ = Air speed.

Since drag force is proportional to dynamic pressure, we can calculate a drag coefficient, $C_dA$ :

$CdA\ =\ \frac{Drag}{p_{dyn}}$

Dynamic pressure is just the difference between total pressure (the pressure measured by the little tube in the centre of aerosensor) and the static pressure (ambient pressure):

$pDyn\ =\ p_T-p_S$

Measuing dynamic pressure

Aerosensor cannot measure the true static pressure because it sits close to the bike, where the flow is already slowing down. Instead it measures a slightly different static pressure, $p_{aero}$ .

From aerodynamic theory the difference can be expressed as the pressure coefficient, $Cp_{aero}$ .

$C_{p_{aero}}=\frac{p_{aero}-p_s}{p_T-p_s}$

What aerosensor actually measures is $dp$ :

$dp=p_T-p_{aero}$

Expanding this and substituting in $C_{p_{aero}}$ :

$dp=(p_T-p_S)-(p_{aero}-p_S)$

$dp=p_{dyn}-C_{p_{aero}} p_{dyn}$

$dp=(1-C_{p_{aero}}) p_{dyn}$

Rearranging:

$p_{dyn}=\frac{dp}{1-C_{p_{aero}}}$

Aero device calibration

This leads to the aero device calibration, $cal$ :

$cal=\frac{1}{1-C_{p_{aero}}}$

So the corrected dynamic pressure is calculated by:

$p_{dyn}=cal\times dp$

How it's calculated in practice

In the real world, where there may be wind, calibration is derived from an out-back run or a single lap of a closed circuit, based on the assumption that the average wind is zero.

Aerosensor calculates:

The average measured pressure $dp$ .
The average dynamic pressure inferred from wheel speed.

Dividing (2) by (1) gives you the calibration factor for that run.

Post-correcting for updated calibration factor

CdA can be post-corrected for calibration factor as follows:

${CdA}_{new}=\ {CdA}_{old}\times\frac{{cal}_{old}}{{cal}_{new}}$

Where:

$CdA_{old}$ = CdA reported by Aerosensor.
$cal_{old}$ = Calibration factor entered in settings in CIQ app.
$cal_{new}$ = new calibration factor you want to apply.
$CdA_{new}$ = corrected CdA.

Both Aeroportal and Aeroworkbook do this automatically when you change the calibration factor.

However, this correction is not perfect in every case. To calculate altitude, we need accurate dynamic pressure. On velodromes, altitude is ignored, so calibration can be corrected perfectly afterwards. On out-and-backs, large errors in calibration will reduce CdA accuracy.

For example:

On an out-back run, a 10% error in calibration, combined with a 25% variation in speed across the lap, results in about a 1.5% error in CdA.
If speed were perfectly constant through the lap, the error would be zero.

Keeping your speed consistent between runs reduces the impact of calibration error on your results.

Section 2

Articles

Article 2.1

Aerobody

Articles

Quickstart

What follows outlines the basic setup of Aerobody. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerobody setup

1. Install device using Garmin ¼-turn mount.

2. Position device. Using your hand to check, rotate Aerobody so the head sensor is picking up your chin. Tighten mount screw to lock in position.

3. Open either ACS or Aerobody datafield on Garmin device.

4. Connect Aerobody to CIQ app.

a. Turn on Aerobody. It should connect automatically. If not:

b. Menu > Connections > Aerobody.

c. Wait for CIQ app to find device, then click on it to connect.

5. Set your datum position using the app or datafield.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Device basics

Specifications

Dimensions (H x W x D)	36 x 32 x 64mm
Mass	37g
Battery Life	9 hours
Head position resolution	+/- 1mm
Chest position resolution	+/- 1mm

Layout

LED
Power button
Reset button
USB-C bung & charging port
Head sensor
Chest sensor
Quarter-turn mount

Button functions

Power button:
- Press and release to turn on.
- Press and hold until LED turns off then release to shut down.
Reset button:
- To be used in case the device becomes unresponsive.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Aqua	Normal	On	Unplugged	Normal
Red	Normal	On	Unplugged	Low
Amber	Slow	Off	Plugged in	Charging
Amber	Solid	On	Plugged in	Charging
Green	Slow	Off	Plugged in	Charged
Green	Solid	On	Plugged in	Charged

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Important notes & prerequisites

Important notes

Aerobody uses optical sensors for measuring your body position, so keeping the sensor lenses clean and free from debris is critical for good performance.

The USB port should be kept dry and free from debris. After charging, please ensure that the bung is replaced firmly.

Although Aerobody is splashproof, it is not designed to operate in wet conditions. Please ensure it is removed if outdoors and raining.

Clean Aerobody with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerobody doesn’t require any other devices to work; you will need a Garmin cycling computer however.

Device mounts

Aerobody has been designed to work on a variety of different bike bar types, notably the following:

Drop handlebars – usually standard on road bikes and track bikes.
Clip-on time-trial (TT) bars – additions to road and track bikes.
Integrated TT handlebar/cockpit – mostly seen on TT and triathlon specific bikes.

Aerobody is supplied with a quarter-turn mount suitable for most bike setups.

Whilst Aerobody can be used on most bike setups, there will be some bar variants that may be trickier to setup. Please do not hesitate to contact us at hello@Aerosensor.tech with any questions or for advice on how to best mount onto your bike.

Installation

Aerobody has a standard Garmin quarter-turn mount. It should be positioned on the stem using a compatible bike mount adapter such as the one supplied with the unit. The screw on the quarter-turn mount allows pitch adjustment of the entire unit.

The forward (head) sensor should be aligned approximately with the chin and the chest sensor points at the chest.

To align, support the bike either in a turbo trainer, or by asking someone to support the bike. Sitting on the bike in your normal riding position watch the display whilst moving two fingers up and down from your chin towards the unit, and ensure that the measurement tracks movement of your fingers.

CIQ App

Aerobody Connection

Make sure that Aerobody is switched on.

Press the menu button on the Garmin head unit.
Select “Connections” -> “Aerobody”.

3. Select the device you want to connect to. Note: it is worth keeping a note of the Device ID for your Aerobody for your records, especially if you are a coach and have multiple devices for your riders.

Set Reference

The CIQ app shows your body position relative to a reference which you can set as follows:

Got to Menu-> Aerobody Settings->Set Reference.
Get into your ideal position on the bike. To do this support the bike in a turbo trainer, or ask someone to support it for you, and get into your normal riding position.
Select “Measure”. This will give you a 5 second countdown to get in position, then will take a 2 second average of your position. When complete the measurements will show in red to indicate the new values are unsaved, and the “Save” button will be highlighted.
Click “Save” to send the new position to Aerobody. Wait for the head and chest display to update to green, and the save button to turn grey and show “Saved”.

Set Null Zone

The body position fields in the CIQ app will turn red if you are higher, or blue if you are lower, than your reference position. It will be white if you are within a set “null zone” around your reference position. As an example, a 1.5cm null zone means that the rider moving between -1.5cm and +1.5cm of their reference head or chest position will remain white whilst riding. Anything outside of these values are considered “out of position” will be red or blue depending if you are too high or too low.

The null zone may be set as follows:

Got to Menu-> Aerobody Settings->Set Null Zone.
The buttons can be used to adjust in multiples of 1cm and 0.1cm as necessary.
Click “Save” to send the new position to Aerobody.

Aerobody information

Got to Menu -> Aerobody settings -> About

Here you can see information about your Aerobody device, including battery level, firmware version and serial number. Battery voltage is also included as it is useful for diagnostic purposes.

CIQ Datafield

Please refer to the Aerobody CIQ Datafield section here.

Test Section

New documentation

Articles

Section 1

Article 1.1

Section 2 Article 2.1

Article 1.2

Recommended protocol

aerosensor calibration

Recommended Protocol

General approach: Run a baseline first, update your calibration factor, then continue with your tests.

Velodrome: At least 1500 m (≈6 good laps of a 250 m track).
Out-back: At least 3 out-backs, each 600–1000m in length.

You can select valid laps in the CIQ app and read off the average calibration, or use Aeroportal / Aeroworkbook to do the same.

There are a few things to bear in mind based on test type.

Indoor Velodrome

Calibration is easiest on an indoor Velodrome because it there is no wind. A couple of points to watch out for:

Ride alone: Other riders disturb the air, effectively giving you a false tailwind.
Limit calibration laps: Only use the first ~5 laps for calibration (set under Advanced settings → Max calibration laps in the Aeroworkbook and under Edit run in Aeroportal). After that, you start creating your own “tailwind.” Think of the velodrome as a giant cup of tea and yourself as the spoon — circulation builds gradually, but eventually it affects your data.

Outdoor Velodrome

Outdoors you don’t generate your own tailwind, but you will almost always encounter some ambient wind.

Collect at least 1500m of data (≈6 laps of a 250 m track).
More laps generally improve reliability.

Out-Back testing

Two main issues affect out-back calibration:

Traffic: Passing cars, motorbikes, or cyclists disturb the air and create headwinds or tailwinds. The more traffic, the less reliable your calibration.
Consistency of start/end point: Local features (trees, buildings, hedges) influence wind patterns. If your “out” and “back” sections don’t overlap exactly, calibration accuracy suffers.

Best practice:

Choose quiet roads and times with minimal traffic.
Keep start/stop points, acceleration, and deceleration as consistent as possible.
The more consistent your testing, the more consistent the results.

Aerodrome

Articles

Quickstart

What follows outlines the basic setup of Aerodrome. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerodrome Setup

Install tapeswitch across track, securing with duck tape.
Position Aerodrome about 1-2 meters downstream of the tapeswitch, close to track, oriented so that the buttons are closest to the track as shown.
Ensure Aerodrome blue light is flashing
When Aerosensor is on and within a few meters of the Aerodrome the light will flash to show it is able to communicate with it. This ensures radio signal is strong enough to work. It only needs to pick up Aerosensor’s signal for 1-2 meters after the tapeswitch is crossed.
Open ACS in “Velodrome Tracked” mode.
This assumes no elevation changes, and uses the trackmap to correct for cyclist lean angle.
Edit track map in ACS.
See section in CIQ app documentation.

Remember to start an activity on the Garmin before starting to ride. Aerosensor will automatically create new laps every time you cross the tapeswitch. Note that the data appears on the Garmin a couple of seconds after the end of lap, once Aerosensor has finished averaging data for the lap.

Aero testing guidance

Reliable aerodynamic testing is reliant on good testing protocols. Here are a few tips for best results.

CdA data is only as accurate as the inputs. Make sure you check Aerosensor’s settings in the ACS app before every test.
Always calibrate power sensor before starting testing. Small calibration offsets can result in a big error in CdA measurement.
Always start and end your test block with a baseline repeat.
Try to maintain a constant speed through each run.
For velodrome testing we recommend 6-8 laps per configuration.
The more laps you do, the better the repeatability will be.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Device basics

Specifications

Dimensions (H x W x D)	34 x 76 x 76mm
Mass	66g
Battery Life	28 hours
Timing resolution	+/- 1ms

Layout

Power button
LED
Reset button
USB-C charging port
Tapeswitch port

Button functions

Power button:
- Press and release to turn on.
- Press and release to shut down.
Reset button:
- To be used in case the device becomes unresponsive.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Cyan	Solid	On	Unplugged	Normal
Lilac	Solid	Trigger	N/A	N/A
Amber	Solid	On	Charger	Low
Green	Solid	Off	Charger	Charging
Blue	Solid	On	Computer	Charging
Light blue	Solid	Off	Computer	Charged
Any	Flash	On	Aerosensor connected

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Important notes & prerequisites

Important notes

Aerodrome uses a Tapeswitch cable as a lap trigger – the cable should not be pinched or bent. Bending with a bend radius less than 4mm will permanently damage the product.

The USB port and Tapeswitch port should be kept dry and free from debris.

Although Aerodrome is splashproof, it is not designed to operate in wet conditions. Please ensure it is not used outdoors when it is raining.

Clean Aerodrome with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerodrome requires Aerosensor device and a Garmin cycling computer.

Installation

As Aerodrome will likely be used on a live track or a public road, it is critical that you have permission to use the device and/or have taken appropriate measures to ensure not only the safety of you and other riders, but also to prolong the life of the device itself.

The tapeswitch should be placed so that the flat side is against the track or road, and the ridge on the upper side. Using duck tape, secure the tapeswitch across the line the cyclist will be following, be it on the track or the road. Secure at the far ends with tape, and placing a further piece of tape along the length, just holding down the upstream side of the tapeswitch.

Tape along the tapeswitch, not across it (as below).

Aerodrome listens for Aerosensor and the LED flashes when it receives data. It is only able to transmit the lap trigger when this is happening.

For optimal radio performance, make sure Aerodrome is situated in a position where it can receive data from Aerosensor when bike is at or just past the Tapeswitch. It is normally best to position 1-2m downstream of where the lap trigger is placed. Orient the device so that the buttons are closest to the track, as shown in images below.

Plug the tapeswitch plug into the Aerodrome socket and turn on. The power light should illuminate. You can check it is working by pressing on the tapeswitch. The LED will turn purple for 1 second to indicate a lap trigger.

Aerodrome should be placed on the floor well clear of any area the rider is likely to pass. Secure the tapeswitch cable to the floor with duck tape to avoid trip hazards.

Note that currently Aerodrome cannot distinguish between multiple Aerosensor’s running on track. It will only work correctly when a single rider is on track.

CIQ App

Aerodrome Connection

Aerodrome uses Aerosensor, so no specific settings are required in the CIQ App.

Please refer to the Aerosensor section here.

Device basics

Specifications

Dimensions (H x W x D)	135 x 57 x 85mm
Mass	66g
Battery Life	57 hours
Wind speed resolution	+/- 0.1%
Wind angle resolution	+/- 0.1°
Altitude resolution	+/- 10cm

Layout

LED
Power button
Reset button
USB-C bung & charging port
Stem
Height/yaw adjustment screw
Go-pro mount

Button functions

Power button:
- Press and release to turn on.
- Press and hold until LED turns off then release to shut down.
- Press and hold, push reset button, then release for full factory reset. This resets the internal settings used to calculate CdA.
Reset button:
- To be used in case the device becomes unresponsive. Resets device without erasing settings.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Aqua	Normal	On	Unplugged	Normal
Red	Normal	On	Unplugged	Low
Amber	Slow	Off	Plugged in	Charging
Amber	Solid	On	Plugged in	Charging
Green	Slow	Off	Plugged in	Charged
Green	Solid	On	Plugged in	Charged

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Garmin CIQ Apps & Datafields

Articles

Aerosensor Cycling System CIQ App

Overview

The Aerosensor Aerodynamic Cycling System (ACS) Connect IQ app is required to seamlessly integrate our devices with your Garmin bike computer, providing real-time aerodynamic data and further insights during your ride, and recording your data to a FIT file for further analysis.

Installation

The Aerosensor ACS CIQ app can be downloaded from the Garmin Connect IQ website:

https://apps.garmin.com/

Simply search for “Aerosensor” and the app will come up, or use this link:

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

Install to the Garmin head unit as per the instructions on the CIQ app website.
Start ACS by going to the Connect IQ menu on your Garmin (see Garmin instructions) and then selecting “Aerosensor ACS”.

ACS screen layout

FIT file recording status:
Red square = not recording
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status:
Green = Connected.
Orange = Searching.
Red = Disconnected.
Aerosensor battery status.
Back key
Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key.
This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerobody CIQ Datafield

Overview

Aerobody is a device that mounts on your stem and measures the distance to your head and chest. This is a good indication of your overall body position.

The Aerobody datafield allows you to view your body position data in the context of your normal Garmin views. You can add it in the same way you would add any other data such as speed, power, time etc. It also adds your aerobody data to the fit file so you can view it after your ride.

Installation

Search for Aerobody on the ConnectIQ store and follow instructions to install.

Once installed, on your Garmin select the data screen (in your chosen activity profile) and edit the field where you want the data to appear.
Select Connect IQ from the list.
Select Aerobody from the list.

Note that aerobody really needs a full screen width field to display correctly as it displays both head and chest positions.

Pairing

Turn on your Aerobody device.

The Aerobody datafield will automatically connect to the first Aerobody signal it picks up. It saves this so that next time it will look for the same physical device.

If you need to switch to a different Aerobody device, firstly make sure that only that one is switched on and in range (roughly 10m) of the Garmin unit, the follow the following steps.

Make sure that Garmin Connect app is installed on your phone and paired with your Edge unit.
Turn on your Garmin and the Aerobody device.
In either Garmin Connect or the Garmin ConnectIQ app, select your device, then go find the datafield app. Open settings.
Move the slider next to “Reset paired device” to the right.
Click “Save”. The display on the Garmin should show “Reconnecting” for 3 seconds then switch back to the data view. Ensure that a surface is within 300mm of the Aerobody device in order to make sure it is reading data.

Setting datum

Aerobody allows you to set a datum, which you can think of as a target position for you to maintain whilst riding. The head and chest fields will go red if you go above this; blue if below, outside of a “null zone”, the dimensions of which you can modify in the settings. You can also set an audible alert to warn you when you are outside of your target range. By default the relative position is shown in the fields, which is the distance between your current position and the datum. This can be changed to absolute position in the datafield settings.
To set your datum, follow these steps:

Get on the bike, ready to get into position. Use a turbo-trainer or friend to support it.
In settings, put the “Set datum” slider to the right. Click “Save”.
On the datafield it will give you a countdown of 3 seconds to get into position.
The datafield It will then average your position and save it.

Now when you are in the correct position the display should have an uncoloured background. If you are too low it goes blue; too high it goes red.

Installation and Setup

aeroworkbook

Installation and Setup

Download

You can download the AeroWorkbook here:

https://info.aerosensor.tech/docs/start/downloads/excel-tools/

Prerequisites

Since V1.5.5 the FIT files are loaded directly within the Microsoft Excel macros, so Java is no longer required. Similarly the script files which used to be required on mac are no longer needed!

Since there is no longer anything to check on your system the “Check system” button has also been removed.

Checking your system

After carrying out these steps, use the Check System button on the Control worksheet to check that everything is set up correctly on your computer. You should see something like the following. If there is a red x by any item you should check you have done everything correctly.

Setup

Before you load any data you will need to set the aerotool up depending on the testing you are doing. The settings are all on the Control worksheet.

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Basic settings

Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Testing type

Either track or out-back.

Delete raw data

When a FIT file is loaded the raw FIT file data is loaded into worksheets named after each of the 3 data types (record, lap, session). If you want to check the raw data set this field to false. For most purposes you can leave it as true.

Auto calibrate

Aerotool calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Speed units

Select an option from either kph or mph.

Use cloud

Set to true if you want to load data from aeroportal.
Set to false to import locally saved FIT files.

Advanced settings

Most users should not need to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when track testing option selected under basic settings.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Show/Hide definitions

This shows or hides the worksheets where the data definitions are stored. For most users this can be ignored.

Show/Hide log

If aerotool crashes you can show the log and send that information to support@aerosensor.tech for technical support.

Operation

Here is just a quick description of these buttons

Load FIT files

Button opens a dialog to load in FIT files, either file based or aeroportal based, depending on Use cloud settings above.

Recalculate

Button recalculates data for all runs currently loaded.

Reset workbook

Deletes all currently loaded run data.

Check system

Checks the system is set up correctly to enable FIT files to be loaded.

Test

Articles

Test Section

Installation

Use the go-pro mount itself to adjust pitch, then the yaw by loosening the height/yaw screw on Aerosensor’s stem (height adjuster) and rotating the unit.

Do not use the aerosensor base to pivot, this can cause damage to the stem.

When installing, it is important to have Aerosensor as far forward and low as possible that the stem allows to minimise influence of rider position.

The base must be at least 20mm above the front wheel.
It should be centred on the bike and facing forwards. Use the front wheel as a reference for yaw alignment.
Aerosensor should be level – use a horizontal object to the side of the bike (like floor markings), and visually align the bottom of Aerosensor with the horizontal line. An example is shown below, where a horizontal line on the wall is used. Note that the device is tolerant to pitch misalignment within +/-5°.

Testing

aerosensor testing

Introduction

Here you can find all the information you need for accurate aerodynamic testing on the road or track. Open the appropriate section.

You can download a pdf of these instructions by clicking the button below.

Articles

Expected repeatability

aerosensor testing

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Expected repeatability

Outdoors you should be able to achieve the following repetability so long as average wind speed is less than 25% of cycling road speed. If wind speed is above 50% we do not recommend aero testing.

Out-back testing

+/-1.5%

Outdoor velodrome with aerodrome

+/-1.0%

Indoor velodrome with aerodrome

+/-0.5%

For good repeatability careful setup is essential. In particular:

Ensure power meter is calibrated before each run.
Make sure total mass is correct for every run.
Carefully measure the loaded circumference of the wheels (seated roll-out).

Terminology

aerosensor testing

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Terminology

For clarity, its please note the following terminology taht will be used througout this section.

Session

A series of runs covering various bike and rider configurations.

Run

A set of consecutive laps with the bike and rider in a single configuration.

Lap

Either a single track lap, or an “Out” or “Back” leg in out-back testing.

Out Lap

Segment riding at speed away from your starting point.

Back Lap

Segment riding at speed towards your starting point.

Out-back

A pair of consecutive Out and Back Laps.

Baseline

A known starting configuration of bike and rider.

Aerosensor settings

aerosensor testing

Aerosensor settings

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Basic settings

To function correctly, Aerosensor requires the following inputs, entered in the ConnectIQ app here:
Menu → Aerosensor settings → Basic settings:

Aerosensor calibration

Calibration is reported for every run and depends on bike setup. Minor changes (helmet, wheels) have little effect, but adjustments to handlebar height, reach, or sensor position can significantly impact results.

Begin each session with 2 runs and compare reported calibration to the current setting.
If it differs by more than 5%, update it before continuing.

Total mass

Mass affects acceleration, gravity, and rolling resistance, making it critical for accuracy.

Weigh yourself before each session, including bike, gear, and accessories.
Carry fluids on the bike so total weight remains consistent as you drink.
If you refill bottles or use the loo, re-weigh before continuing.

Wheel circumference

Measure the circumference of only the wheel with the speed sensor. This depends on tires, wheels, pressure, and system weight. To measure:

Align a piece of tape on the wheel and ground.
Sit on the bike and roll forward one full revolution.
Mark the new ground position and measure the distance between marks.

Reference Crr (Coefficient of Rolling Resistance)

Find Crr values for your tires and pressure at: https://www.bicyclerollingresistance.com/

Crr depends on road roughness but has a small, consistent effect on CdA measurements.
If testing on a velodrome (wood track), reduce Crr by ~40%.
Example: A road Crr of 0.0035 should be 0.002 on a velodrome.

If unsure the following table shows some typical values for smooth tarmac.

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Tyre Type	Tyre pressure
Tyre Type	60psi	80psi	100psi	120psi
CLINCHER: TT	0.0044	0.0037	0.0033	0.0030
CLINCHER: ALL-ROUNDER	0.0056	0.0047	0.0042	0.0040
CLINCHER: ALL-WEATHER	0.0072	0.0061	0.0055	0.0052
TUBELESS: TT	0.0033	0.0028	0.0026	0.0024
TUBELESS: ALL-ROUNDER	0.0049	0.0042	0.0037	0.0035
TUBELESS: ALL-WEATHER	0.0057	0.0050	0.0044	0.0041
TUBULAR	0.0053	0.0046	0.0042	0.0039

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Advanced Settings

These are settings that you are likely to change less frequently, but nevertheless important. You can find them in the CIQ app here:
Menu → Aerosensor settings → Advanced settings:

Power Meter Scaling

Some power is lost in the drivetrain due to friction (chain, bearings, derailleur, etc.).

Pedal, crank-arm, or spider-based power meters → Set to 0.98 (accounts for ~2% drivetrain loss).
Hub-based power meters → Set to 1.00 (measures power directly at the wheel).

CTF Calibration Offset

For SRM PM7 and older power meters only. Enter the calibration value displayed on your Garmin after calibration (typically ~520).

Time Averaging Period

CdA (not CdA lap) is a rolling average over this time period. It does not affect lap values (e.g., out-back or track testing).

Recommended: 30 seconds (default).

Valid Brake Deceleration

AeroSensor automatically starts a new lap when braking to exclude braking forces from calculations.

Default: 1 m/s²
If using Aerodrome lap trigger: set to 10 m/s² to avoid inadvertently triggering laps for example when going up banking after last lap.

Valid Speed Min

Laps start automatically when speed rises above this threshold.

When testing without Aerodrome lap trigger, set it just below target test speed.
Why? Power meters and speed sensors have small time offsets, which can introduce drag measurement errors if accelerating hard through a low threshold.
Hysteresis: Once speed exceeds the threshold, Aerosensor will not trigger another lap unless speed drops 1 m/s (3.6 km/h) below it.

Braking Time Offset

When braking, Aerosensor discards the last N seconds of data to prevent braking forces from affecting lap CdA calculations.

Recommended: 5 seconds (default).

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Aerosensor Setting Summary

Basic settings

Menu → Aerosensor settings → Basic settings

Setting	Default	Note
Aero device calibration	1.18	Measure yours in testing. Start with 1.4 if unsure.
Total mass	75 kg	Weigh before testing. Includes bike etc.
Wheel circumference	2115 mm	Measure with weighted rollout.
Reference Crr	0.00375	Look up (see table above)

Advanced Settings

Menu → Aerosensor settings → Advanced settings

Setting	Default	Note
Power meter scaling	0.98	Unless using hub based, keep at this value.
CTF Calibration offset	0 Hz	Enter value shown on Garmin after power meter calibration (SRM PM6/7 only).
Time av period	30 s	Rolling average period for CdA
Valid brake deceleration	1 m/s²	Auto lap if brake with deceleration greater than this.
Valid speed min	25.2 kph	Auto lap when speed goes above this value or drops below.
Braking time offset	5 s	Data within this time of braking event is discarded from CdA calculation.

Testing Checklist

aerosensor testing

Testing checklist

Here is a handy checklist to help make sure you are ready to test!

Before Opening CIQ App

Speed sensor paired to Garmin?
Power meter paired to Garmin?
Power meter calibrated?
Power meter auto-cal off (if possible)?

Open CIQ App

Set correct testing type.
Connected to Aerosensor?
Aerosensor paired with speed/power sensors?

Aerosensor Settings

Essentials (Check Before Every Session)

These settings have a major impact on accuracy and must be verified before each test:

Aerosensor calibration set? (Check after 3× out-and-backs; update if >5% off).
Total mass correct? (Weigh before each session; includes rider, bike, and gear).
Wheel circumference measured/set? (Ensure correct value for current tire pressure).
Reference Crr correct? (Adjust for road/velodrome).
Valid speed min set? (Just below target test speed for out-back/track testing).

Less critical (Minimal Impact on Data, Adjust as Needed)

Valid brake deceleration set? (1 m/s² default; 10 m/s² for Aerodrome testing).
Braking time offset set? (Default: 5s).
Time averaging period set? (Default: 30s; only affects rolling CdA, not lap values).

Aerobody Settings (if applicable)

Aerobody connected?
Aerobody datum set?

Session Protocol

aerosensor testing

Session protocol

The testing protocol is the same for all test types.

Aero calibration

It is really important to consider the aero calibration when designing your run plan.

Aerosensor reports a calibration factor for each run to account for airflow slowing as it approaches the bike.

You need to consider the following in order to handle it correctly:

After the first baseline run, update the aero cal in the ACS app.
During testing, if it shifts by more than 5%, update it in the app to minimize altitude calculation errors.
- If this happens in out-back testing, update value then repeat the run.
Expect consistent aero calibration for the same configuration.
Biggest changes occur with body position, stack height, bar angle, etc.

Run plan

Baseline consistency is critical in aerodynamic testing. A known, repeatable configuration ensures accurate comparisons.

Start with two baseline repeats to check system repeatability. Initial drift is common due to power meter offset stabilization and the rider settling in.
End with a baseline run to detect any drift over the session.
Don’t leave more than 10 runs between baselines.

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Run	Configuration	Power meter cal	Aero cal
1	Baseline	Calibrate before run	Last known, or 1.400
2	Baseline (repeat)	Calibrate	Update to calculated
3	First config change.	Calibrate	Keep as last.
4...	Subsequent changes..	Calibrate	Keep as last.
Last	Baseline (final repeat)	Calibrate	Keep as last.

Out-back test protocol

aerosensor testing

Out-back testing protocol

This testing is used when a track is not available.

Road selection criteria

Select a stretch of road, or smooth paved track with the following characteristics:

Traffic: Minimal traffic is best. Aim for fewer than 2 cars per direction per run.
Length: Road should allow 600–1000m of cycling at target speed.
Curvature: Gentle bends are fine, but avoid sections requiring braking or leaning >20°.

Run protocol

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Aim for your target speed, with “Valid speed min” set just below it.
Get into position before reaching this speed.
Around 5 seconds after hitting valid speed, Garmin beeps to acknowledge new lap.
Lap starts when speed threshold is reached.

Ride in Position (600–1000m)

Maintain a steady speed.

Brake Hard to End Lap

Lap automatically ends when deceleration exceeds “Valid brake deceleration”.
The last ~5 seconds of data are excluded from CdA calculation (“Braking time offset”).

Turn Around

Turnaround must take at least 5 seconds to ensure proper lap separation.

Repeat Steps 1–4 in the Opposite Direction

This forms your "Back" lap after completing the "Out" lap.

Complete 3 Out-Back Pairs

Three out-back pairs are recommended because:
- They ensure repeatability of results.
- More data improves accuracy, balancing time vs. quality.

End the Session

After the last Back lap, stop the bike, then press Start/Stop button on Garmin.

Velodrome test protocol with Aerodrome

aerosensor testing

Velodrome testing protocol (with Aerodrome)

This protocol applies to both indoor and outdoor velodromes.

Aerodrome provides highly accurate lap timing (better than 1 ms), generating a separate CdA measurement for each lap. This allows precise tracking of repeatability throughout the session as well as improved accuracy of the data.

Run protocol

You can only test with a single rider on track at any one time.

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

If you are running multiple riders (but only one on track at any one time):

Ensure only 1 aerosensor is switched on. This avoids interference with aerodrome signal.
If using lap logger, ensure only 1 Garmin is running the ACS app. This avoid interference with the lap logger.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Take 1–2 laps to build up to target speed as you normally would.

Start Flying Lap

Cross the lap trigger line at your target speed to begin the first flying lap.

Complete Test Laps

Ride 1,500–2,000m at a steady speed (6–8 laps on a 250m track).
Hold position until you cross the lap trigger at the end of your last lap.

Slow Down After Final Lap

Reduce speed gradually after your last fast lap.

End the Session

Bring the bike to a stop, then press Start/Stop button to end the FIT file recording.

Velodrome test protocol without Aerodrome

aerosensor testing

Velodrome testing protocol (Without Aerodrome)

Without Aerodrome, Aerosensor cannot automatically segment data into laps or identify corner geometry. However, you can still achieve good results by following this method.

Run protocol

You can only test effectively with a single rider on track at any one time.

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Take 1–2 laps to build up to target speed.
Keep speed below "Valid speed min" during this phase.

Start Flying Lap

Aim to accelerate above “Valid speed min” at the start of your first flying lap.
Alternative: Use a Garmin remote lap trigger or the Garmin lap button to manually start the lap when crossing the start/finish line

Complete Test Laps

Ride 1,500–2,000m at a steady speed (6–8 laps on a 250m track).

Decelerate After Final Lap

Reduce power naturally after crossing the start/finish line at the end of your last flying lap.
Alternative: Use the Garmin remote lap trigger to manually end the lap.

End the Session

Bring the bike to a stop, then press Start/Stop button to end the FIT file recording.

CIQ App

Aerosensor Connection

Make sure that Aerosensor is switched on.

1. Press the menu button on the Garmin head unit.

2. Select “Connections” -> “Aerosensor”.

3. Select the device you want to connect to. Note: it is worth keeping a note of the Device ID for your Aerosensor and Aerobody for your records, especially if you are a coach and have multiple devices for your riders.

Pass-pairing

Pass-pairing is where ACS transmits the power meter and speed sensor ANT+ connection details to Aerosensor, allowing it to connect to them directly.

For this to work the Garmin unit should already be paired with the ANT+ sensors you are using.

Note that Aerosensor requires a power meter (PWR) AND EITHER a speed sensor (SPD) OR speed + cadence sensor (BSC).

The CIQ app should automatically pass on the sensor connections to Aerosensor. In case this does not work, or you have multiple sensors on the bike, follow these steps:

Ensure that a power meter and speed sensor are installed on the bike and paired with the Garmin. Make sure they are on by rotating the wheel and/or pedals/crank, depending on the power meter.
In the ACS menu, select “Connections”->”Pass pair” which will bring up the following screen:

3. Either select the devices individually or select the bottom “Enter to sync” button in purple above. After a short period, the status bar at the bottom of the screen should go green to show Aerosensor matches the Garmin device. Aerosensor connection status icons should go from red to green.

Aerosensor Parameters

To accurately calculate aerodynamic drag, Aerosensor requires some information about you and your bike:

Aero device calibration: This accounts for the fact that the wind slows as it approaches the bike, so the wind speed measured by Aerosensor is always slower than the air far upstream of the bike. Start with a value of 1.4. Typically we see values beweeen 1.1 and 1.45. See ‘Quickstart’ section for more information.
Total mass (kg): includes rider + bike + all accessories used whilst riding with Aerosensor.
Wheel Circumference (mm). If unknown, you can go into the speed sensor settings on the Garmin and you will find the wheel circumference in there once you have ridden far enough for the Garmin to calibrate against GPS.
Power meter scaling: Default value is 1.0. If using pedals or crank we need to account for drivetrain losses. A typical value would be 0.98, i.e. 2% drivetrain loss.
CTF calibration offset: Used for CTF power meters.
Time av period: This is the time period used by Aerosensor to average the CdA value, default is 30 seconds.
Reference Crr: Rolling resistance coefficient (used if known), default 0.004. For an indoor velodrome you should use 0.002 (half the road value). You can find typical crr values for a range of tyres at https://www.bicyclerollingresistance.com/
Valid speed min: minimum speed (kph) for valid CdA automatic lapping. The CdA calculation is started when you go above this speed, and stopped when you slow down below this speed. The device automatically creates laps for each CdA measurement period.

Editing Parameters:

It is important you check these frequently, especially total mass and wheel circumference if changing between bikes for example.

Velodrome testing – Track layout

When Aerosensor is in track calculation mode it uses lap distance and speed to calculate lean angle to compensate for centre of gravity location. This only works when Aerodrome is being used. A typical track layout is shown below, of which you can input the track measurements by editing parameters directly in the CIQ app.

You can measure the track by measuring relative distance of corner start and end, using the distance markers along the track. This does not need to be very accurate – within a few meters is fine.

Measuring the track:

Measure the distance from the tapeswitch location to the start and end of each corner.
Use these to calculate the total distance of the two straight sections.
Corner length = track length – total straight lengths
Corner radius = corner length / pi
Transition length is the distance it takes for the rider to transition from the straight to the corner. Typical value is 10m.

Example:

Total track length = 250m.
C1 start = 10m
C1 end = 95m
C2 start = 135m
C2 end = 220m
Corner length = C1 end – C1 start – transition= 95 – 10 – 10 = 75m
Corner radius = 75/pi = 23.9m

Editing Parameters:

Velodrome testing – Calculation mode

At the velodrome Aerosensor can ignore the barometer, since elevation is roughly constant, and should use the track map. If the track map is not known, or Aerodrome is not available, you can use the trackless mode. To use Velodrome mode:

Go to Menu-> Aerosensor Settings->Calculation Mode.
Select the model you require:
1. Road
  For road riding.
2. Velodrome Trackless
  Assumes constant elevation but ignores track layout. This is for when you are not using a lap trigger (Aerodrome) or the track layout is unknown.
3. Velodrome Tracked
  Assumes constant elevation AND uses the track layout. This is for when you are using Aerodrome and know the track layout, as entered in ‘Aerosensor Settings->Track’.
Wait until the mode changes as required, in the menu heading.

Screen sequence shown below:

Aerosensor demo mode

This is for diagnostic purposes and can generally be ignored.

Aerosensor information

Go to Menu -> Aerosensor settings -> about

Here you can see information about your Aerosensor device, including battery level, firmware version and serial number. Battery voltage is also included as it is useful for diagnostic purposes.

Loading and viewing data

aeroworkbook

Loading and viewing data

Loading data

For each run you load into the excel tool, a separate worksheet will be created named Run_X where X is the number of the run, starting at 1 for the first one you load. It will also create a Summary worksheet showing data for all runs, and two graphs showing the CdA and power variation to your baseline.

File based system

Change use cloud in basic settings to false.
Click on Load FIT files.
Select one or more FIT files from the file system.

Each FIT file will be loaded in turn.

Aeroportal based system

1. Change use cloud in basic settings to true.
2. Click on Load FIT files.
3. Select one or more FIT file then click the Open
If the FIT file has not been loaded before, it will be saved onto your computer.

On windows files are saved to the following directory:
C:/Users/[UserName]/AppData\Roaming\AerosensorExcel

On Mac they are saved to the following directory: /Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Run analysis

There are a few steps to getting the best accuracy from your data.

On the worksheet for each run you can edit any of the cells highlighted yellow.

Select valid runs

Aeroworkbook will automatically mark runs as valid based on the speed tolerance criteria by putting an X in the Valid column of the Lap summary table, highlighted in yellow.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can whether to use auto cal for this specific run by selecting true or false under Auto cal in row 5.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters in the column marked Setting in device and also copied to Used for calibration when first loaded.

If any of these were not correct, or for example you are not using auto cal and want to manually change the Aero Cal value then can change it here.

Recalculate

Either click Recalculate sheet to recalculate data for the active run sheet, or click Recalculate on the Control worksheet to recalculate all runs. The data is recalculated in the run sheets and also updated in the Summary sheet.

Interpreting data

In the summary sheet you see a list of all of your runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the section “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
     $v =$ Speed (m/sec)

Histograms

On each run sheet histograms of headwind and wind yaw angle are shown for all of the laps marked as valid.

For each headwind bucket it shows the percentage of time spent with that level of headwind.
If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.
This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.
For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Data analysis

For most users, we recommend using our Aeroportal website. On the portal you are able to process, analyse, edit and save your data.

You can create an account on Aeroportal and link it to your Garmin account. This integration allows for the automatic transfer of data from your Garmin device to the portal and the Excel tool, eliminating the need for manual file transfers.

You can also use our aeroworkbook macro-enabled Microsoft Excel workbook for processing and analyzing data. This tool is straightforward, reliable, and well-suited for a wide range of use cases.

Data Workflow:

Record Activity: Complete your session and save the FIT file on your Garmin device.
Automatic Upload: Garmin uploads the FIT file to Garmin Connect via Bluetooth on your smartphone.
Aeroportal Sync: Aeroportal automatically imports the FIT file from Garmin Connect.
Aeroportal or Excel Tool Download: View your data online on the portal or download the data directly to your computer through the Excel Analysis Tool.

This process ensures a seamless and efficient workflow from recording to analysis.

See articles below for detailed instructions.

Articles

Aeroworkbook

aeroworkbook

Overview

Our AeroWorkbook is a macro-enabled Microsoft Excel workbook that enables easy analysis of FIT files generated with the Aerosensor ACS Garmin Connect IQ app.

Its main features are as follows:

Download FIT files from the our AeroPortal cloud server.
Import FIT file data.
Correct parameters.
Add descriptions and notes to each run.
Select valid laps.
Calculate out-back, lap and run averaged data.
Display histograms showing wind variation.

Quick start

For those in a rush, here is a brief overview of how to use AeroWorkbook:

Click on Load FIT files on the Control This loads either from a local directory or the cloud, depending on whether or not you have Use cloud set to True or not. You can load more than one fit file at once.
Files are each loaded into separate tabs in the AeroWorkbook.
On each run tab, select Valid laps by adding or removing an X in the appropriate column. Laps with an X next to them are the laps that will be used for the run calculation.
If required, you can change the values of the parameters used for calculation.
Either click Recalculate Sheet on that sheet, or click Recalculate on the Control worksheet to recalculate all runs.
Final run data is shown in the Summary.

Installation and Setup

aeroworkbook

Installation and Setup

Download

You can download the AeroWorkbook here:

https://info.aerosensor.tech/docs/start/downloads/excel-tools/

Prerequisites

Since V1.5.5 the FIT files are loaded directly within the Microsoft Excel macros, so Java is no longer required. Similarly the script files which used to be required on mac are no longer needed!

Since there is no longer anything to check on your system the “Check system” button has also been removed.

Checking your system

After carrying out these steps, use the Check System button on the Control worksheet to check that everything is set up correctly on your computer. You should see something like the following. If there is a red x by any item you should check you have done everything correctly.

Setup

Before you load any data you will need to set the aerotool up depending on the testing you are doing. The settings are all on the Control worksheet.

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Basic settings

Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Testing type

Either track or out-back.

Delete raw data

When a FIT file is loaded the raw FIT file data is loaded into worksheets named after each of the 3 data types (record, lap, session). If you want to check the raw data set this field to false. For most purposes you can leave it as true.

Auto calibrate

Aerotool calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Speed units

Select an option from either kph or mph.

Use cloud

Set to true if you want to load data from aeroportal.
Set to false to import locally saved FIT files.

Advanced settings

Most users should not need to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when track testing option selected under basic settings.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Show/Hide definitions

This shows or hides the worksheets where the data definitions are stored. For most users this can be ignored.

Show/Hide log

If aerotool crashes you can show the log and send that information to support@aerosensor.tech for technical support.

Operation

Here is just a quick description of these buttons

Load FIT files

Button opens a dialog to load in FIT files, either file based or aeroportal based, depending on Use cloud settings above.

Recalculate

Button recalculates data for all runs currently loaded.

Reset workbook

Deletes all currently loaded run data.

Check system

Checks the system is set up correctly to enable FIT files to be loaded.

Loading and viewing data

aeroworkbook

Loading and viewing data

Loading data

For each run you load into the excel tool, a separate worksheet will be created named Run_X where X is the number of the run, starting at 1 for the first one you load. It will also create a Summary worksheet showing data for all runs, and two graphs showing the CdA and power variation to your baseline.

File based system

Change use cloud in basic settings to false.
Click on Load FIT files.
Select one or more FIT files from the file system.

Each FIT file will be loaded in turn.

Aeroportal based system

1. Change use cloud in basic settings to true.
2. Click on Load FIT files.
3. Select one or more FIT file then click the Open
If the FIT file has not been loaded before, it will be saved onto your computer.

On windows files are saved to the following directory:
C:/Users/[UserName]/AppData\Roaming\AerosensorExcel

On Mac they are saved to the following directory: /Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Run analysis

There are a few steps to getting the best accuracy from your data.

On the worksheet for each run you can edit any of the cells highlighted yellow.

Select valid runs

Aeroworkbook will automatically mark runs as valid based on the speed tolerance criteria by putting an X in the Valid column of the Lap summary table, highlighted in yellow.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can whether to use auto cal for this specific run by selecting true or false under Auto cal in row 5.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters in the column marked Setting in device and also copied to Used for calibration when first loaded.

If any of these were not correct, or for example you are not using auto cal and want to manually change the Aero Cal value then can change it here.

Recalculate

Either click Recalculate sheet to recalculate data for the active run sheet, or click Recalculate on the Control worksheet to recalculate all runs. The data is recalculated in the run sheets and also updated in the Summary sheet.

Interpreting data

In the summary sheet you see a list of all of your runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the section “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
     $v =$ Speed (m/sec)

Histograms

On each run sheet histograms of headwind and wind yaw angle are shown for all of the laps marked as valid.

For each headwind bucket it shows the percentage of time spent with that level of headwind.
If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.
This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.
For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Editing data

aeroworkbook

Editing data

Creating sessions

Typically you will want to group runs together, for example by test, by creating sessions and then assigning runs to these sessions.

With Use Cloud set to True click on Load FIT files. Log in if requested.

Click on Edit sessions to open the Sessions dialog box.
Click on Create New Session to create a session.
Enter an appropriate name for the session then click Save.

This new session will now be available to assign to runs.

Assigning runs to a session

You can change the session associated with a run by editing the run information as described below. The sessions you created in the step above should all appear in the drop-down menu of the file details dialog.

Editing run information for a single run

With Use Cloud set to True click on Load FIT files. Log in if requested. The following form will show listing all of the runs available. Against each run is shown either Cloud or Local: If Local is shown then you have already downloaded the run locally.
Select a run by clicking on it then either click Edit or right-click on the run. It will open this form.
You can edit the Session, Run Description, Run notes and Used values which are the parameter values that aeroworkbook will use for calculations.
Click Save to update the information in the aeroportal database for that run.

Editing run information for multiple runs

Select multiple runs that you want to edit, then either click Edit or right-click on the runs to edit them.
The same File details form will open as before. Here you can only edit session, and Used values Values that are common for your runs will show in the dialog. Where values differ the associated field in the form will be blank.
Click Save to save these edited values for all runs.

Glossary

aeroworkbook

Glossary

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FIT file data

Fit files have 3 types of data. For each type there will be multiple variables such as power, speed etc.

Record

This is the time series data, recorded at 1Hz: one value per second.

Lap

One value per lap.

Session

One value for the entire FIT file.

Lap or Out-Back Summary Metrics

In the run data there are many columns. Some are self-explanatory but others are explained below.

Dist revs

Lap distance in wheel revolutions.

Av speed

Average speed over the lap = lap distance / lap time.

Yaw

Average wind yaw angle.

Abs Yaw

Average of the absolute yaw angle, where negative values are treated as positive.

Yaw SD

Standard deviation of the 1Hz yaw data over the lap. Indicator of how gusty the wind is.

Headwind

Headwind speed = wind speed resolved along direction of travel, minus wheel speed.

Headwind SD

Standard deviation of the 1Hz headwind data over the lap. Indicator of how gusty the wind is.

Pressure

Ambient air pressure.

Records

Number of 1Hz samples present in the lap.

Cal

Aero calibration value for the lap.

CdA

Lap CdA calcualted by aerosensor using the run parameters in the Garmin.

Head

Head position measured with aerobody.

Chest

Chest position measured with aerobody.

pXXXX

Average power values. Positive averages power in to the bike, negative is power out.

pRider

Average rider power.

pAero

Aero drag power

pGrav

Gravitational power (power used to propel up hill, or gained from going downhill).

pFric

Rolling resistance power

pKin

Kinetic power, i.e. if bike is accelerating then power is consumed by increase in kinetic energy.

pPdyn

Dynamic pressure power – this is basically average of speed x dynamic pressure. CdA = -pAero / pPdyn.

pXXXCor

_Cor suffix denotes values corrected for specified Used for calculation values under Run parameters.

CdAFinal

This is the CdA value corrected for specified run parameters and for the calculated aero calibration if Auto cal is set to true. If Auto cal is set to false then CdAFinal = CdACor.

Spd Mag Droprate

Aerosensor tries to detect where a magnet pass event is missed by the speed sensor. This is the rate of magnet pass “drops”. Should be zero.

Spd ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from speed sensor. Generally not an issue but useful for debugging. There will always be some dropped packets.

Pwr ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from power meter. Generally not an issue but useful for debugging. There will always be some dropped packets.

Run Data Metrics

These are the values shown near the top of the run worksheet.

Laps

Number of laps used for run calculation.

Av Speed

Average speed of all laps.

pRiderCor

Average rider power for all laps.

CdA Final

Final corrected CdA with calculated calibration applied if using Auto cal.

Cal Cor

Corrected calibration factor

CdAF+/-

Maximum lap CdA Final variation from the average, in m2.

CdAF+/-%

Maximum lap CdA Final variation from the average, as percentage of average.

Cal+/-%

Maximum Calibration factor variation from the average, as percentage of average.

Head

Average head position.

Chest

Average chest position.

Yaw

Average wind yaw angle, treating negative values as negative.

Abs Yaw

Average wind yaw angle, treating negative values as positive.

Yaw SD

Wind yaw angle standard deviation.

Headwind

Average headwind speed.

Hwind SD

Headwind standard deviation.

CdA Cor

Corrected CdA but if Auto Cal is used, without calibration factor applied.

FAQs

aeroworkbook

Frequently asked questions

Where are my aeroportal files stored locally?

Normally you shouldn’t need to go there, but in case you do:

Windows

On Microsoft Windows the files are saved locally to the following directory, where [UserName] is your username:

C:\Users\[username]\AppData\Roaming\AerosensorExcel

MacOS

On Mac the files are saved locally to the following directory, where [username] is your username:

/Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Can I work on aeroportal files offline?

Yes!

Make sure you download all the files you need while you are online:

Click on Load FIT files.
Select all the files you need which still have Cloud marked next to them in the list.
Click Download to save those files locally.

You can now load the files through the same Load FIT files dialog.

Note: You can only edit run details whilst online and logged into your aeroportal account.

Aeroportal

aeroportal

Overview

Aeroportal is our online platform designed to simplify your data analysis. You can automatically sync FIT files from Garmin Connect, making them accessible through Aeroportal itself, or our Excel Aeroworkbook.

Its main features are as follows:

Pair your Aeroportal and Garmin accounts for automatic importing and storing of FIT files generated with our ACS Connect IQ app.
Correct parameters.
Add descriptions and notes to each run.
Select valid laps.
Organise your runs into sessions.
Calculate out-back, lap and run average data.
Display histograms showing wind variation.

Important: Only FIT files recorded with our ACS Connect IQ app will be transferred to the Aeroportal server. All other FIT files will be ignored.

Quick start

For those in a rush, here is a brief overview of how to setup your Aeroportal account and view your runs:

After creating an account, pair your Aeroportal and Garmin accounts together, and request a Backfill in the settings page or sync some new runs through Garmin Connect.
Use the File Menu (button with three horizontal lines) to see a table of your available runs.
If desired, create Sessions to organise your runs by pressing the sessions tab in the file menu.
If required, you can change the data parameter values of runs by selecting them and and clicking the Edit button. You can also set their sessions here.
Select all runs you wish to view and click the View button.
Click on a Run in the run list on the left hand side, and select Valid laps in the Lap Summary table under the Laps tab, and click Save Laps & Recalc. Valid laps are the laps that will be used for the run calculation.
Final run data is shown in the Summary item in the run list.

Layout and Account Setup

aeroportal

Aeroportal Layout

The following screenshots show various components of the aeroportal webpage.

Analysis page:

File Menu:

Open Runs:

Aeroportal account

Registration

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Register here” and complete the registration form.
Check your email for a confirmation link and click it to verify.
You should now be able to login to the Aeroportal.

Resetting your password

If you have forgotten your password to log in to Aeroportal, you can request an email to reset it.

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Reset here” and type in the email address associated with your aeroportal account.
Check your email for a reset link and click it.
Type in your new password.
Log in with your new credentials.

Garmin account

Pairing Garmin Account

Login to portal.aerosensor.tech.
On the settings page, under Garmin Integration click the Register with Garmin button.
Log in to your Garmin Connect account when prompted. If you have multiple Garmin accounts ensure you are logged into the correct one.
Follow the on-screen instructions to complete the pairing process.

Unpairing Garmin account

To disconnect your Garmin account from Aeroportal:

Login to portal.aerosensor.tech
On the settings page, under Garmin Integration click the Deregister with Garmin
In the popup press Deregister

To disconnect your Garmin account from Aeroportal via Garmin Connect:

Log in to your Garmin Connect account.
Click your profile logo in the top-right corner, then select Account Settings.
In the left-hand menu, choose Account Information.
Under Aeroportal, click Disconnect.

Backfill (Importing historical data)

After you have paired you Aeroportal and Garmin accounts together, the backfill feature allows you to import FIT files uploaded to Garmin Connect before your Aeroportal and Garmin accounts were paired. Once logged into Aeroportal, go to the “Settings” page via button at top of screen.

Log in to the Aeroportal and navigate to Settings via the top menu.
Under Garmin Integration, find the Backfill Data button.
Use the date pickers to select a start and end date. Note: The selected date range must not overlap with dates already downloaded. If it does, unlink and relink the Aeroportal app to Garmin Connect before retrying.

Click “Request backfill data”. The files will download in the background.
To confirm the import, check the available files either in the Aeroportal file menu or the Excel Aeroworkbook
Note: it can take a few minutes for the files to be pulled across to our cloud servers.

Editing Data and Run Setup

aeroportal

Editing runs

Once you have paired your Garmin account and have some files available on our server, you can set persistent descriptions, notes, sessions and metrics for your runs.

Editing a single run

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Use the Pencil Icon to the right of a run to edit data for the corresponding run.
This will open a new menu which will allow you to edit the Session, Run Description, Run notes, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and will be available for use.

If you want to quickly set/edit a description for a run, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the run you want to edit.
Type your new description.
Click away from the Description to save it.

Editing multiple runs

Editing multiple runs at once is a convenient way to assign a session or change values for the selected runs.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select multiple runs by using the checkboxes on the left and clicking the Edit button to edit the selected runs (e.g. assigning a session to multiple runs).
This will open a new menu which will allow you to edit the Session, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and are available for use.

Deleting one or more runs

Sometimes you may want to delete a run, for example, if you backfilled and have multiple runs that are the same. Note: This is a permanent action and to get these runs back you will have to submit a backfill request with the appropriate dates. We also do not recommend deleting runs that were “Errors” during testing, as we will implement a “Hide Run” option in the future, that will allow your run numbering in sessions to stay consistent.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select one or more runs by using the checkboxes on the left and clicking the More button next to Edit and View.
Press the Delete selected button.
Press Yes on the popup.

Editing sessions

Sessions are a way to organise, and group runs.

Viewing/Editing your sessions

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
The table will now list all your sessions, including how many runs are currently assigned to a session.
Use the Create New button to create a new session and set its description.
Use the Pencil Icon on the right of a session to edit it.
You can assign runs to sessions as described in the section above.

If you want to quickly set/edit a description for a session, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the session you want to edit.
Type your new description.
Click away from the Description to save it.

Deleting a session

Sometimes you may want to delete a session. Note: This will NOT delete the runs associated with that session, but they will instead be set to not belonging to a session.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
Click the Pencil Icon to the right of a session to edit it.
Click the Delete session button.
Press Yes on the popup.

Setup before viewing runs.

Before viewing your available runs there are some settings you may want to check.

Run specific settings

These settings may be modified by following the steps above in “Editing runs”.

Basic run settings:

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Testing type

Either track or out-back. Note: Aeroportal automatically picks up what option you selected when starting the run on the Garmin device and sets it appropriately, but it can still be changed if needed.

Auto calibrate

Aeroportal calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Advanced Run Settings:

Most users should not have to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when the run is set to Testing Type: Track.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Device wide settings

These are settings that will be applied to all the runs you view. They are found in the Settings page accessible through the cog icon in the top right corner.

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Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Speed units

Select an option from either kph or mph.

Viewing Data

aeroportal

Viewing your runs

Once you have paired your Garmin account and have some files available on our server, you can view your runs. If needed, you can refer to the screenshots in Layout and Account Setup.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
If you have runs available, they will be displayed in the table.
Select all the runs you would like to view using the checkboxes on the left.
Press the View button on the top right.
After a couple of seconds, all runs will be opened and displayed.
By default, the Summary tab will be displayed which contains a table with information about all currently viewed runs, and charts may be viewed by pressing the corresponding tabs at the top.
You can view individual runs by selecting them from the list view on the left hand side.

Note: You can use the Group by Sessions slider to display runs based on session. You can also open all runs belonging to a session directly from the Sessions tab in the file menu.

Run analysis

There are a few steps to getting the best accuracy from your data.

Select valid runs

Aeroportal will automatically mark laps as valid based on the speed tolerance criteria by selecting the checkbox in the valid column in the Laps summary table.

The Laps summary table can be found by clicking on a run in the list view on the left, and clicking on the Laps tab at the top.
Under the Valid column, you can select/deselect laps to be marked as valid.
Once you are happy with your selection, press the Save Laps & Recalc button, to save your lap selection to our server and recalculate the run. This will also update information in the Summary for all viewed runs. Note: Next time you open this run in the aeroportal, it will be loaded with your valid lap configuration.

Note: If you would like to reset a runs valid laps to its defaults, you can press the Reset Valid Laps button.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can set whether to use auto cal for this specific run by selecting true or false under Auto cal by following the guidance in the section Editing Data and Run Setup.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters section of the Summary tab of an open run. “Default” marks the Setting in device and also copied to “Used” for calibration when first loaded.

If any of these were not correct, or for example you are not using Auto Cal and want to manually change the Aero Cal value then you can set it by following the instructions in “Editing a single run”.

Recalculate

When changing values such as Run Metrics, Auto Cal, Test Type etc, you can open the file menu, check that the runs you want to view are selected, and press View again. This will recalculate the files with your saved values, update individual runs and also update the Summary tab.

Interpreting data

In the summary tab you see a list of all of your viewed runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the column grouping “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
$v =$ Speed (m/sec)

Histograms

On each run in the main list of runs to the left, histograms of headwind and wind yaw angle are shown for all of the laps marked as valid, under the Charts tab on the top.

For each headwind bucket it shows the percentage of time spent with that level of headwind.

If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.

This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.

For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Aerosensor Lap Logger

aerosensor lap logger

Introduction

The Aerosensor Lap Logger is software that lets a coach monitor data from the ACS Connect IQ app trackside.

The Garmin device running the Connect IQ app transmits lap data continuously via an ANT dongle, enabling a connected computer to display and record results in real time. This immediate feedback helps coaches make quick, informed decisions before the rider leaves the track. The lap end data flow is as follows:

Aerosensor takes roughly 3 seconds to send lap end data after receiving lap trigger because of the lap averaging process.

Important notes

When testing multiple riders in the same session, only one Aerosensor should be powered on. The Aerodrome sends lap triggers to the first Aerosensor it detects after each lap, so having multiple sensors active can cause conflicts.
The Lap Logger receives data from all ACS apps in range, so only one Garmin running the ACS app should be used during testing. Multiple Garmins can confuse the logger and result in inaccurate data. The lap logger will warn you if it detects multiple Garmins running the ACS app.

Installation

Compatibility: The software currently runs on Windows only
Download: Available under the "Live lap viewer" section at: https://aerosensor.tech/pages/downloads
ANT+ Dongle Required: For example, the Garmin dongle: https://www.garmin.com/en-GB/p/10997
Optimal Reception: Use a 2m USB extension cable to place the dongle higher up for better signal quality.

Operation

Launch the Application
- From the Start menu, search for ANT_Lap_Logger or use the desktop shortcut. A main window will appear.

Choose a Save Location
- Click Browse and select a folder to store the log files.
Connect the Sensor
- Click Connect and confirm that “Sensor opened” appears.
- In the Messages window, if the ACS app is open on the Garmin, you should see incoming data packets.
- If no data appears, click Close then Open to reset the connection.
- Packet Details: The first byte is the packed ID, and each complete lap message has three packets starting with “0,” “4,” and “8,” ending with the lap number. Lap data only appears once all three packets have been received.
Start a Run
- Click Reset to clear previous data from the LapData grid.
- Enter the run description in the Description field (editable anytime before stopping the log).
- Click Start log to begin recording data.
Note that if there are laps already showing in the lap logger it will give you the option to delete them all. If you want to keep them simply click “No” and these previous laps will be recorded to your log file also.
Monitor Lap Data
- As each lap arrives, use the Flag checkbox to include or exclude laps. The session data displays the average of all flagged laps.

End the Session

Click Stop log to save the data and close the log file.

Access the Log File

Popout window

Click the open popout button in the main window to open a separate window with larger format text. This can be helpful if you need to see key data from a distance, for example if you as the coach want to stand by the start/finish line and shout out lap times to the rider.

Settings

Application settings can be edited from the File->Settings menu:

Number of laps to use for calibration:
Automatically apply average calibration
CSV file separator

Status indicators

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Connection

Closed: ANT USB device connection is not opened. Click “Open” under “Garmin connection”.
Not receiving: Connection to ANT USB device is open but no data is being received.
Receiving: Data is being received from the Garmin. Note you do not need good reception for the entire lap, only for a couple of seconds or so minimum.
“Multiple Garmins!”: Multiple Garmin bike computers running the ACS app are within range. Please turn off the ACS app on the Garmin not in use.

Latest lap: Lap number of most recent complete lap.
Lap data: Each lap requires 3 “packets” of data. These packets are sent 8 times in sequence.
Lap Status: When the Garmin is first turned out it sends packets with no data. These laps are marked as “Invalid”.

For any support queries, please email us at support@aerosensor.tech.

Aerodynamic basics

aerodynamics basics

What is aerodynamic drag?

Aerodynamic drag is the force of the air acting to slow down a cyclist moving through it.

It is made up of two major components – pressure drag and skin friction drag.

Pressure drag is related to the size and shape of the bike and rider. As you cycle forwards you hit air particles out of the way. These are compressed on impact but then space out as they pass over and past you – the difference between these two air pressures is pressure drag. This is why getting into an aerodynamic position and allowing the oncoming air to flow smoothly around you, reduces your overall aerodynamic drag and makes it easier to cycle.
Skin friction is related to the roughness or texture of the surface on the bike and rider, a smooth (laminar) surface allows air particles to have consistent trajectories (pathlines). A rough (turbulent) surface causes irregular pathlines. Something to note however is surface roughness can be used to keep flow attached longer (for example a textured should on a skinsuit) which increases skin friction drag, but reduces pressure drag (of which is a larger component and therefore can reduce overall drag.

How do we measure aerodynamic drag?

There are five forces acting on a cyclist. Aerosensor works by measuring or estimating forces (or power) from the rider (F_R), kinetic (F_K), gravitational (F_G) and friction (F_F) to find the fifth, aerodynamic drag (F_D).

The sum of these sources (positive) and sinks (negative) plus the aerodynamic drag (sink) must equal zero:

$F_{R} \pm F_{K} \pm F_{G}-F_{F}-F_{D}=0$

Aerodynamic drag is comprised of the product of dynamic pressure (p_Dyn, directly measured by Aerosensor), coefficient of drag (C_d, a constant for a given body position/setup) and frontal area (A). In cycling, the coefficient of drag and frontal area are commonly combined as the term CdA:

$F_{D} = p_{\text{Dyn}} \times C_{d}A$

Combining these two equations gives you a relationship between CdA and the other bike forces:

$C_{d}A = \frac{{F_{R} \pm F_{K} \pm F_{G} – F_{F}}}{{p_{\text{Dyn}}}}$

This is what your Aerosensor calculates in real-time!

Why is aerodynamic drag important?

Although aerodynamic drag increases with speed, friction does not – so at high speeds aerodynamic drag dominates.

Above you can see that at 5kph just 10% of your power goes into overcoming aerodynamic drag, and at 40kph this increases to over 80% – ie 80% of your power is used only to push you through the air.

Say you’re taking part in a flat 40km TT, how can reducing your CdA (and therefore aerodynamic drag) affect your race time?

In this example, reducing your CdA by around 10% can save over 1 minute and 30 seconds. The great news about aerodynamic testing is that you can make huge strides in making yourself faster and/or saving more energy for when it matters.

Calibration

aerosensor calibration

For those in a hurry

No time to read the details? Here’s the short version:

Why calibrate?
Air slows down ahead of the bike, so Aerosensor’s dynamic pressure reading must be scaled up. This is called Aero Device Calibration in the CIQ app, or simply Aero Calibration or Cal in Aeroportal and Aeroworkbook.
What affects calibration?
Bike setup, rider position, sensor location – even helmet choice can make a small difference.
How is it done?
A calibration is calculated for every out-and-back run or lap of the velodrome, assuming zero average headwind.
What affects calibration accuracy?
Since we assume zero average headwind anything affecting the wind consistency will affect this. Wind variability (shown as Hwind SD – headwind standard deviation in particular) will degrade accuracy.
How accurate does it need to be?
Keep the CIQ app calibration factor within 5% of the measured value:
- For out-and-back tests, this is critical because it also affects altitude correction.
- For velodrome tests, this is less critical. Since altitude is not used (assumed to be constant) calibration can be corrected perfectly afterwards.
How do I use it in post-processing?
Both Aeroportal and Aeroworkbook offer Auto Cal, which applies the correct factor automatically. They also show:
- 🟢 Green: repeatable calibration, stable wind → Auto Cal can be used confidently.
- 🟠 Orange: some variability → check baseline repeatability; only use Auto Cal for smaller changes (<2%).
- 🔴 Red: inconsistent data → Auto Cal not valid; only test changes that don’t affect calibration, with a constant calibration.
Why does this matter?
All aero devices require calibration, even if others hide it. Aerosensor gives you full visibility and control, so you can trust the results based on what you saw and tested. It’s a little extra work, but it leads to more reliable data.

Articles

Introduction

aerosensor calibration

Introduction

What’s the problem?

As air approaches a cyclist, it slows down due to the build-up of high pressure in front of the bike and rider.
The CFD image below (from this site) shows air speed around a rider in three positions. We’ve added a red arrow to mark the typical Aerosensor location.

You can see:

Rider position changes how much the flow slows down.
In some cases, the slowdown begins well upstream of the bike.

Our own wind tunnel tests confirm this effect (figure 2). Even one metre in front of the bike, air speed is still reduced by 2–3%. Unfortunately, there’s no practical way to mount a sensor far enough forward to avoid this.

This isn’t unique to Aerosensor – it’s just physics. All on-bike aerodynamic devices face the same challenge. The best we can do is minimise the effect by placing the sensor as far forward as possible, then correct for it through calibration.

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What’s the solution?

We overcome this problem by calibrating the sensor.

In still air, road speed and true airspeed are the same. By comparing road speed to the sensor’s measured airspeed, we can calculate a calibration factor that scales the reading back to freestream conditions.

As long as the rider position and setup remain unchanged, this calibration factor will also stay constant.

Technical detail

aerosensor calibration

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Technical detail (optional bedtime reading..)

If you’re mainly interested in how to use Aerosensor, you can skip this section. The details here are for those who want to understand the physics behind the calibration process.

Aerodynamic basics

Aerodynamic force generally scales with dynamic pressure - the pressure increase you’d get if moving air was brought to rest.

The formula for this is:

$p_{dyn}=\frac{1}{2}\rho V^2$

Where:

$p_{dyn}$ = dynamic pressure (Pa)
$\rho$ = air density
$V$ = Air speed.

Since drag force is proportional to dynamic pressure, we can calculate a drag coefficient, $C_dA$ :

$CdA\ =\ \frac{Drag}{p_{dyn}}$

Dynamic pressure is just the difference between total pressure (the pressure measured by the little tube in the centre of aerosensor) and the static pressure (ambient pressure):

$pDyn\ =\ p_T-p_S$

Measuing dynamic pressure

Aerosensor cannot measure the true static pressure because it sits close to the bike, where the flow is already slowing down. Instead it measures a slightly different static pressure, $p_{aero}$ .

From aerodynamic theory the difference can be expressed as the pressure coefficient, $Cp_{aero}$ .

$C_{p_{aero}}=\frac{p_{aero}-p_s}{p_T-p_s}$

What aerosensor actually measures is $dp$ :

$dp=p_T-p_{aero}$

Expanding this and substituting in $C_{p_{aero}}$ :

$dp=(p_T-p_S)-(p_{aero}-p_S)$

$dp=p_{dyn}-C_{p_{aero}} p_{dyn}$

$dp=(1-C_{p_{aero}}) p_{dyn}$

Rearranging:

$p_{dyn}=\frac{dp}{1-C_{p_{aero}}}$

Aero device calibration

This leads to the aero device calibration, $cal$ :

$cal=\frac{1}{1-C_{p_{aero}}}$

So the corrected dynamic pressure is calculated by:

$p_{dyn}=cal\times dp$

How it's calculated in practice

In the real world, where there may be wind, calibration is derived from an out-back run or a single lap of a closed circuit, based on the assumption that the average wind is zero.

Aerosensor calculates:

The average measured pressure $dp$ .
The average dynamic pressure inferred from wheel speed.

Dividing (2) by (1) gives you the calibration factor for that run.

Post-correcting for updated calibration factor

CdA can be post-corrected for calibration factor as follows:

${CdA}_{new}=\ {CdA}_{old}\times\frac{{cal}_{old}}{{cal}_{new}}$

Where:

$CdA_{old}$ = CdA reported by Aerosensor.
$cal_{old}$ = Calibration factor entered in settings in CIQ app.
$cal_{new}$ = new calibration factor you want to apply.
$CdA_{new}$ = corrected CdA.

Both Aeroportal and Aeroworkbook do this automatically when you change the calibration factor.

However, this correction is not perfect in every case. To calculate altitude, we need accurate dynamic pressure. On velodromes, altitude is ignored, so calibration can be corrected perfectly afterwards. On out-and-backs, large errors in calibration will reduce CdA accuracy.

For example:

On an out-back run, a 10% error in calibration, combined with a 25% variation in speed across the lap, results in about a 1.5% error in CdA.
If speed were perfectly constant through the lap, the error would be zero.

Keeping your speed consistent between runs reduces the impact of calibration error on your results.

Recommended protocol

aerosensor calibration

Recommended Protocol

General approach: Run a baseline first, update your calibration factor, then continue with your tests.

Velodrome: At least 1500 m (≈6 good laps of a 250 m track).
Out-back: At least 3 out-backs, each 600–1000m in length.

You can select valid laps in the CIQ app and read off the average calibration, or use Aeroportal / Aeroworkbook to do the same.

There are a few things to bear in mind based on test type.

Indoor Velodrome

Calibration is easiest on an indoor Velodrome because it there is no wind. A couple of points to watch out for:

Ride alone: Other riders disturb the air, effectively giving you a false tailwind.
Limit calibration laps: Only use the first ~5 laps for calibration (set under Advanced settings → Max calibration laps in the Aeroworkbook and under Edit run in Aeroportal). After that, you start creating your own “tailwind.” Think of the velodrome as a giant cup of tea and yourself as the spoon — circulation builds gradually, but eventually it affects your data.

Outdoor Velodrome

Outdoors you don’t generate your own tailwind, but you will almost always encounter some ambient wind.

Collect at least 1500m of data (≈6 laps of a 250 m track).
More laps generally improve reliability.

Out-Back testing

Two main issues affect out-back calibration:

Traffic: Passing cars, motorbikes, or cyclists disturb the air and create headwinds or tailwinds. The more traffic, the less reliable your calibration.
Consistency of start/end point: Local features (trees, buildings, hedges) influence wind patterns. If your “out” and “back” sections don’t overlap exactly, calibration accuracy suffers.

Best practice:

Choose quiet roads and times with minimal traffic.
Keep start/stop points, acceleration, and deceleration as consistent as possible.
The more consistent your testing, the more consistent the results.

Editing data

aeroworkbook

Editing data

Creating sessions

Typically you will want to group runs together, for example by test, by creating sessions and then assigning runs to these sessions.

With Use Cloud set to True click on Load FIT files. Log in if requested.

Click on Edit sessions to open the Sessions dialog box.
Click on Create New Session to create a session.
Enter an appropriate name for the session then click Save.

This new session will now be available to assign to runs.

Assigning runs to a session

You can change the session associated with a run by editing the run information as described below. The sessions you created in the step above should all appear in the drop-down menu of the file details dialog.

Editing run information for a single run

With Use Cloud set to True click on Load FIT files. Log in if requested. The following form will show listing all of the runs available. Against each run is shown either Cloud or Local: If Local is shown then you have already downloaded the run locally.
Select a run by clicking on it then either click Edit or right-click on the run. It will open this form.
You can edit the Session, Run Description, Run notes and Used values which are the parameter values that aeroworkbook will use for calculations.
Click Save to update the information in the aeroportal database for that run.

Editing run information for multiple runs

Select multiple runs that you want to edit, then either click Edit or right-click on the runs to edit them.
The same File details form will open as before. Here you can only edit session, and Used values Values that are common for your runs will show in the dialog. Where values differ the associated field in the form will be blank.
Click Save to save these edited values for all runs.

Quickstart

What follows outlines the basic setup of Aerobody. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerobody setup

1. Install device using Garmin ¼-turn mount.

2. Position device. Using your hand to check, rotate Aerobody so the head sensor is picking up your chin. Tighten mount screw to lock in position.

3. Open either ACS or Aerobody datafield on Garmin device.

4. Connect Aerobody to CIQ app.

a. Turn on Aerobody. It should connect automatically. If not:

b. Menu > Connections > Aerobody.

c. Wait for CIQ app to find device, then click on it to connect.

5. Set your datum position using the app or datafield.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Glossary

aeroworkbook

Glossary

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FIT file data

Fit files have 3 types of data. For each type there will be multiple variables such as power, speed etc.

Record

This is the time series data, recorded at 1Hz: one value per second.

Lap

One value per lap.

Session

One value for the entire FIT file.

Lap or Out-Back Summary Metrics

In the run data there are many columns. Some are self-explanatory but others are explained below.

Dist revs

Lap distance in wheel revolutions.

Av speed

Average speed over the lap = lap distance / lap time.

Yaw

Average wind yaw angle.

Abs Yaw

Average of the absolute yaw angle, where negative values are treated as positive.

Yaw SD

Standard deviation of the 1Hz yaw data over the lap. Indicator of how gusty the wind is.

Headwind

Headwind speed = wind speed resolved along direction of travel, minus wheel speed.

Headwind SD

Standard deviation of the 1Hz headwind data over the lap. Indicator of how gusty the wind is.

Pressure

Ambient air pressure.

Records

Number of 1Hz samples present in the lap.

Cal

Aero calibration value for the lap.

CdA

Lap CdA calcualted by aerosensor using the run parameters in the Garmin.

Head

Head position measured with aerobody.

Chest

Chest position measured with aerobody.

pXXXX

Average power values. Positive averages power in to the bike, negative is power out.

pRider

Average rider power.

pAero

Aero drag power

pGrav

Gravitational power (power used to propel up hill, or gained from going downhill).

pFric

Rolling resistance power

pKin

Kinetic power, i.e. if bike is accelerating then power is consumed by increase in kinetic energy.

pPdyn

Dynamic pressure power – this is basically average of speed x dynamic pressure. CdA = -pAero / pPdyn.

pXXXCor

_Cor suffix denotes values corrected for specified Used for calculation values under Run parameters.

CdAFinal

This is the CdA value corrected for specified run parameters and for the calculated aero calibration if Auto cal is set to true. If Auto cal is set to false then CdAFinal = CdACor.

Spd Mag Droprate

Aerosensor tries to detect where a magnet pass event is missed by the speed sensor. This is the rate of magnet pass “drops”. Should be zero.

Spd ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from speed sensor. Generally not an issue but useful for debugging. There will always be some dropped packets.

Pwr ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from power meter. Generally not an issue but useful for debugging. There will always be some dropped packets.

Run Data Metrics

These are the values shown near the top of the run worksheet.

Laps

Number of laps used for run calculation.

Av Speed

Average speed of all laps.

pRiderCor

Average rider power for all laps.

CdA Final

Final corrected CdA with calculated calibration applied if using Auto cal.

Cal Cor

Corrected calibration factor

CdAF+/-

Maximum lap CdA Final variation from the average, in m2.

CdAF+/-%

Maximum lap CdA Final variation from the average, as percentage of average.

Cal+/-%

Maximum Calibration factor variation from the average, as percentage of average.

Head

Average head position.

Chest

Average chest position.

Yaw

Average wind yaw angle, treating negative values as negative.

Abs Yaw

Average wind yaw angle, treating negative values as positive.

Yaw SD

Wind yaw angle standard deviation.

Headwind

Average headwind speed.

Hwind SD

Headwind standard deviation.

CdA Cor

Corrected CdA but if Auto Cal is used, without calibration factor applied.

Troubleshooting

Articles

Aerosensor

Aerosensor won’t turn on

We have a known issue where Aerosensor can become unresponsive.

Make sure device has charge by plugging into USB-C.
Press reset button. You can find instructions on where to find it in the quickstart.

In addition, our device works on a standard 5V power supply. Some laptop/phone charges are “smart chargers” that communicate with device to charge at a higher voltage. These just flat out don’t work, so please try the following:

Try a different power source. A computer USB port is usually a safe bet.
Try a different USB cable, just in case that is the problem. Rare but it has happened that the USB cable isn’t suitable.

If the LED doesn’t come on after this, please reach out to our support team.

CdA not showing (invalid or zero)

It is likely that Aerosensor is not correctly paired to your ANT+ sensors.

BLE/ANT+ sensors transmit as both BLE and ANT+ separately. You may have paired to the BLE sensor. In the Garmin go to the sensor, and check that you are paired to the ANT+ sensor.
Check that the ANT+ power meter AND EITHER speed OR speed and cadence sensor is paired properly. Ensure the sensors are on by rotating pedals/crank/wheel then check pass-pairing (in CIQ app go to Connections->Pass Pairing). When properly paired the SPD and PWR icons in the top right hand corner of the CIQ app will show green.

CdA doesn’t match expectation

There are a few reasons Aerosensor may report an incorrect CdA value.

Check that you have entered an appropriate Aero Calibration factor in the CIQ app (Aerosensor settings->Parameters->Edit Parameters). For instructions on how to get this value see the quickstart guide.
Make sure you have calibrated the power meter.
Make sure that other Aerosensor parameters (in particular Total Mass, Wheel Circumference, Power meter scaling, Reference Crr) are correct.
If using a pedal based power meter, ensure that the crank length is set correctly in the Garmin Power Meter sensor settings.

Aerosensor won’t update

If Aerosensor is not able to connect to the aerosensor updater then it is likely the USB-C cable is power only, not power + data. Try a different cable.

We have also noticed that USB-C to USB-C chargers don’t work for updater for this reason.

Aerobody

Aerodrome

Too many laps

If, when using Aerodrome, more laps are shown than expected, it is likely that you are experiencing drop-outs in the speed sensor.

This means that Aerosensor sporadically auto-laps independent of Aerodrome.

Try moving your magnet speed sensor to the front wheel, this should fix the issue.

Tutorial Videos

This area is currently in construction – stay tuned for more videos soon!

Articles

Aerosensor Setup

In this video we show you how to setup our cycling aerodynamic drag measurement device, Aerosensor: From unboxing through to testing the setup on a turbo trainer.

Aerobody Setup

In this video we show you how to set Aerobody up on the bike, and use both the ACS Connect IQ (CIQ) app, and the Aerobody Datafield to set it up and view the data.

Excel Analysis Tool

Find out how to use our Aerosensor Excel Analysis Tool, enabling you to get the most of your aerodynamic cycling data and make conclusions about your testing quickly and with confidence.

This video takes you from installation on your Windows or Mac computers, through to loading, editing, and analysing the data.

FAQs

aeroworkbook

Frequently asked questions

Where are my aeroportal files stored locally?

Normally you shouldn’t need to go there, but in case you do:

Windows

On Microsoft Windows the files are saved locally to the following directory, where [UserName] is your username:

C:\Users\[username]\AppData\Roaming\AerosensorExcel

MacOS

On Mac the files are saved locally to the following directory, where [username] is your username:

/Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Can I work on aeroportal files offline?

Yes!

Make sure you download all the files you need while you are online:

Click on Load FIT files.
Select all the files you need which still have Cloud marked next to them in the list.
Click Download to save those files locally.

You can now load the files through the same Load FIT files dialog.

Note: You can only edit run details whilst online and logged into your aeroportal account.

Device basics

Specifications

Dimensions (H x W x D)	36 x 32 x 64mm
Mass	37g
Battery Life	9 hours
Head position resolution	+/- 1mm
Chest position resolution	+/- 1mm

Layout

LED
Power button
Reset button
USB-C bung & charging port
Head sensor
Chest sensor
Quarter-turn mount

Button functions

Power button:
- Press and release to turn on.
- Press and hold until LED turns off then release to shut down.
Reset button:
- To be used in case the device becomes unresponsive.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Aqua	Normal	On	Unplugged	Normal
Red	Normal	On	Unplugged	Low
Amber	Slow	Off	Plugged in	Charging
Amber	Solid	On	Plugged in	Charging
Green	Slow	Off	Plugged in	Charged
Green	Solid	On	Plugged in	Charged

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Layout and Account Setup

aeroportal

Aeroportal Layout

The following screenshots show various components of the aeroportal webpage.

Analysis page:

File Menu:

Open Runs:

Aeroportal account

Registration

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Register here” and complete the registration form.
Check your email for a confirmation link and click it to verify.
You should now be able to login to the Aeroportal.

Resetting your password

If you have forgotten your password to log in to Aeroportal, you can request an email to reset it.

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Reset here” and type in the email address associated with your aeroportal account.
Check your email for a reset link and click it.
Type in your new password.
Log in with your new credentials.

Garmin account

Pairing Garmin Account

Login to portal.aerosensor.tech.
On the settings page, under Garmin Integration click the Register with Garmin button.
Log in to your Garmin Connect account when prompted. If you have multiple Garmin accounts ensure you are logged into the correct one.
Follow the on-screen instructions to complete the pairing process.

Unpairing Garmin account

To disconnect your Garmin account from Aeroportal:

Login to portal.aerosensor.tech
On the settings page, under Garmin Integration click the Deregister with Garmin
In the popup press Deregister

To disconnect your Garmin account from Aeroportal via Garmin Connect:

Log in to your Garmin Connect account.
Click your profile logo in the top-right corner, then select Account Settings.
In the left-hand menu, choose Account Information.
Under Aeroportal, click Disconnect.

Backfill (Importing historical data)

After you have paired you Aeroportal and Garmin accounts together, the backfill feature allows you to import FIT files uploaded to Garmin Connect before your Aeroportal and Garmin accounts were paired. Once logged into Aeroportal, go to the “Settings” page via button at top of screen.

Log in to the Aeroportal and navigate to Settings via the top menu.
Under Garmin Integration, find the Backfill Data button.
Use the date pickers to select a start and end date. Note: The selected date range must not overlap with dates already downloaded. If it does, unlink and relink the Aeroportal app to Garmin Connect before retrying.

Click “Request backfill data”. The files will download in the background.
To confirm the import, check the available files either in the Aeroportal file menu or the Excel Aeroworkbook
Note: it can take a few minutes for the files to be pulled across to our cloud servers.

Important notes & prerequisites

Important notes

Aerobody uses optical sensors for measuring your body position, so keeping the sensor lenses clean and free from debris is critical for good performance.

The USB port should be kept dry and free from debris. After charging, please ensure that the bung is replaced firmly.

Although Aerobody is splashproof, it is not designed to operate in wet conditions. Please ensure it is removed if outdoors and raining.

Clean Aerobody with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerobody doesn’t require any other devices to work; you will need a Garmin cycling computer however.

Device mounts

Aerobody has been designed to work on a variety of different bike bar types, notably the following:

Drop handlebars – usually standard on road bikes and track bikes.
Clip-on time-trial (TT) bars – additions to road and track bikes.
Integrated TT handlebar/cockpit – mostly seen on TT and triathlon specific bikes.

Aerobody is supplied with a quarter-turn mount suitable for most bike setups.

Whilst Aerobody can be used on most bike setups, there will be some bar variants that may be trickier to setup. Please do not hesitate to contact us at hello@Aerosensor.tech with any questions or for advice on how to best mount onto your bike.

Downloads

Articles

Demo FIT Files

Out-back FIT file

Download demo FIT file to try out-back analysis using our excel tool and other platforms.

Updated 24th March 2025.

Velodrome FIT files

Demo FIT files. See notes text file for more information.

Updated 24th March 2025.

Garmin Connect IQ Apps & Datafields

ACS App

Aerosensor Cycling System app lets you get the most from our unique system of aerodynamic development devices.

Aerobody Datafield

View your body position as you ride, in the context of your favourite data screens with a datafield dedicated to Aerobody.

Aeroworkbook

aeroworkbook for Windows and Mac

Import Aerosensor FIT files directly to excel, and perform basic out-back and velodrome analysis.

V5.1.9 updated 18th November 2025.

Trackside Lap Logger

Aerosensor lap logger

View and log lap data trackside on a Windows computer.

V1.4.1, updated 13th March 2025.

ANT+ dongle driver

Windows driver for ANT+ USB dongle.

Firmware Updater

Aerosensor Updater for Windows

Update your aerosensor and aerodrome firmware to the latest version using a Windows laptop or desktop computer.

Note: For updating, a USB-A to USB-C cable to connect the device to your laptop/computer is required. If your laptop/computer only has USB-C ports then a USB-C to USB-A adaptor is needed.

Please note that updates are only available for Aerosensor and Aerodrome.

Updated 27th September 2024 to V1.11

Aerosensor Updater for macOS

Update your aerosensor and aerodrome firmware to the latest version using an Apple Mac laptop or desktop computer.

Note: For updating, a USB-A to USB-C cable to connect the device to your Mac is required. If your Mac only has USB-C ports then a USB-C to USB-A adaptor is needed.

A macOS version of 12.4 or higher is required.

Please note that updates are only available for Aerosensor and Aerodrome.

Updated 31st October 2025 to V1.16

WKO Charts

WKO CHART

Chart layout for viewing Aerosensor data in WKO V4 or V5.

(01.11.23 Update)

Note that WKO does not show the lap or session data, only the record data, which is the time history.

CAD Files

The CAD files are provided for free use; however, users assume all associated risks. Aerosensor disclaims any responsibility for loss or injury resulting from the use of these files.

Current Aerosensor stay

Includes stay and fairing, plus assembly.

Updated Aerosensor stay

One-piece stay released February 2024.

Pressure Scanner

AeroDAQ for Windows

Configure and record data from your SC-01 Pressure Scanner with our Windows AeroDAQ software.

Updated 5th December 2025 to V1.0

SC-01 User Manual

Hardware, Software and User Programming Manual for our SC-01 Pressure Scanners.

Updated 5th December 2025 to V1.0

SC-01 Specification

Specification sheet for our SC-01 Pressure Scanners.

Updated 5th December 2025 to V1.0

Installation

Aerobody has a standard Garmin quarter-turn mount. It should be positioned on the stem using a compatible bike mount adapter such as the one supplied with the unit. The screw on the quarter-turn mount allows pitch adjustment of the entire unit.

The forward (head) sensor should be aligned approximately with the chin and the chest sensor points at the chest.

To align, support the bike either in a turbo trainer, or by asking someone to support the bike. Sitting on the bike in your normal riding position watch the display whilst moving two fingers up and down from your chin towards the unit, and ensure that the measurement tracks movement of your fingers.

Editing Data and Run Setup

aeroportal

Editing runs

Once you have paired your Garmin account and have some files available on our server, you can set persistent descriptions, notes, sessions and metrics for your runs.

Editing a single run

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Use the Pencil Icon to the right of a run to edit data for the corresponding run.
This will open a new menu which will allow you to edit the Session, Run Description, Run notes, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and will be available for use.

If you want to quickly set/edit a description for a run, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the run you want to edit.
Type your new description.
Click away from the Description to save it.

Editing multiple runs

Editing multiple runs at once is a convenient way to assign a session or change values for the selected runs.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select multiple runs by using the checkboxes on the left and clicking the Edit button to edit the selected runs (e.g. assigning a session to multiple runs).
This will open a new menu which will allow you to edit the Session, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and are available for use.

Deleting one or more runs

Sometimes you may want to delete a run, for example, if you backfilled and have multiple runs that are the same. Note: This is a permanent action and to get these runs back you will have to submit a backfill request with the appropriate dates. We also do not recommend deleting runs that were “Errors” during testing, as we will implement a “Hide Run” option in the future, that will allow your run numbering in sessions to stay consistent.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select one or more runs by using the checkboxes on the left and clicking the More button next to Edit and View.
Press the Delete selected button.
Press Yes on the popup.

Editing sessions

Sessions are a way to organise, and group runs.

Viewing/Editing your sessions

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
The table will now list all your sessions, including how many runs are currently assigned to a session.
Use the Create New button to create a new session and set its description.
Use the Pencil Icon on the right of a session to edit it.
You can assign runs to sessions as described in the section above.

If you want to quickly set/edit a description for a session, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the session you want to edit.
Type your new description.
Click away from the Description to save it.

Deleting a session

Sometimes you may want to delete a session. Note: This will NOT delete the runs associated with that session, but they will instead be set to not belonging to a session.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
Click the Pencil Icon to the right of a session to edit it.
Click the Delete session button.
Press Yes on the popup.

Setup before viewing runs.

Before viewing your available runs there are some settings you may want to check.

Run specific settings

These settings may be modified by following the steps above in “Editing runs”.

Basic run settings:

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Testing type

Either track or out-back. Note: Aeroportal automatically picks up what option you selected when starting the run on the Garmin device and sets it appropriately, but it can still be changed if needed.

Auto calibrate

Aeroportal calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Advanced Run Settings:

Most users should not have to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when the run is set to Testing Type: Track.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Device wide settings

These are settings that will be applied to all the runs you view. They are found in the Settings page accessible through the cog icon in the top right corner.

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Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Speed units

Select an option from either kph or mph.

CIQ App

Aerobody Connection

Make sure that Aerobody is switched on.

Press the menu button on the Garmin head unit.
Select “Connections” -> “Aerobody”.

3. Select the device you want to connect to. Note: it is worth keeping a note of the Device ID for your Aerobody for your records, especially if you are a coach and have multiple devices for your riders.

Set Reference

The CIQ app shows your body position relative to a reference which you can set as follows:

Got to Menu-> Aerobody Settings->Set Reference.
Get into your ideal position on the bike. To do this support the bike in a turbo trainer, or ask someone to support it for you, and get into your normal riding position.
Select “Measure”. This will give you a 5 second countdown to get in position, then will take a 2 second average of your position. When complete the measurements will show in red to indicate the new values are unsaved, and the “Save” button will be highlighted.
Click “Save” to send the new position to Aerobody. Wait for the head and chest display to update to green, and the save button to turn grey and show “Saved”.

Set Null Zone

The body position fields in the CIQ app will turn red if you are higher, or blue if you are lower, than your reference position. It will be white if you are within a set “null zone” around your reference position. As an example, a 1.5cm null zone means that the rider moving between -1.5cm and +1.5cm of their reference head or chest position will remain white whilst riding. Anything outside of these values are considered “out of position” will be red or blue depending if you are too high or too low.

The null zone may be set as follows:

Got to Menu-> Aerobody Settings->Set Null Zone.
The buttons can be used to adjust in multiples of 1cm and 0.1cm as necessary.
Click “Save” to send the new position to Aerobody.

Aerobody information

Got to Menu -> Aerobody settings -> About

Here you can see information about your Aerobody device, including battery level, firmware version and serial number. Battery voltage is also included as it is useful for diagnostic purposes.

Viewing Data

aeroportal

Viewing your runs

Once you have paired your Garmin account and have some files available on our server, you can view your runs. If needed, you can refer to the screenshots in Layout and Account Setup.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
If you have runs available, they will be displayed in the table.
Select all the runs you would like to view using the checkboxes on the left.
Press the View button on the top right.
After a couple of seconds, all runs will be opened and displayed.
By default, the Summary tab will be displayed which contains a table with information about all currently viewed runs, and charts may be viewed by pressing the corresponding tabs at the top.
You can view individual runs by selecting them from the list view on the left hand side.

Note: You can use the Group by Sessions slider to display runs based on session. You can also open all runs belonging to a session directly from the Sessions tab in the file menu.

Run analysis

There are a few steps to getting the best accuracy from your data.

Select valid runs

Aeroportal will automatically mark laps as valid based on the speed tolerance criteria by selecting the checkbox in the valid column in the Laps summary table.

The Laps summary table can be found by clicking on a run in the list view on the left, and clicking on the Laps tab at the top.
Under the Valid column, you can select/deselect laps to be marked as valid.
Once you are happy with your selection, press the Save Laps & Recalc button, to save your lap selection to our server and recalculate the run. This will also update information in the Summary for all viewed runs. Note: Next time you open this run in the aeroportal, it will be loaded with your valid lap configuration.

Note: If you would like to reset a runs valid laps to its defaults, you can press the Reset Valid Laps button.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can set whether to use auto cal for this specific run by selecting true or false under Auto cal by following the guidance in the section Editing Data and Run Setup.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters section of the Summary tab of an open run. “Default” marks the Setting in device and also copied to “Used” for calibration when first loaded.

If any of these were not correct, or for example you are not using Auto Cal and want to manually change the Aero Cal value then you can set it by following the instructions in “Editing a single run”.

Recalculate

When changing values such as Run Metrics, Auto Cal, Test Type etc, you can open the file menu, check that the runs you want to view are selected, and press View again. This will recalculate the files with your saved values, update individual runs and also update the Summary tab.

Interpreting data

In the summary tab you see a list of all of your viewed runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the column grouping “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
$v =$ Speed (m/sec)

Histograms

On each run in the main list of runs to the left, histograms of headwind and wind yaw angle are shown for all of the laps marked as valid, under the Charts tab on the top.

For each headwind bucket it shows the percentage of time spent with that level of headwind.

If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.

This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.

For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

CIQ Datafield

Please refer to the Aerobody CIQ Datafield section here.

Quickstart

What follows outlines the basic setup of Aerodrome. For more detailed information please refer to the other articles on the left hand side.

ACS Installation

Download the ACS app to your Garmin. Go to Garmin ConnectIQ store and search for “Aerosensor” or use link below.

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

ACS screen layout

FIT file recording status:
Red square = not recording.
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status: Green = Connected. Orange = Searching. Red = Disconnected.
Aerosensor battery status.
Back key Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key. This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerodrome Setup

Install tapeswitch across track, securing with duck tape.
Position Aerodrome about 1-2 meters downstream of the tapeswitch, close to track, oriented so that the buttons are closest to the track as shown.
Ensure Aerodrome blue light is flashing
When Aerosensor is on and within a few meters of the Aerodrome the light will flash to show it is able to communicate with it. This ensures radio signal is strong enough to work. It only needs to pick up Aerosensor’s signal for 1-2 meters after the tapeswitch is crossed.
Open ACS in “Velodrome Tracked” mode.
This assumes no elevation changes, and uses the trackmap to correct for cyclist lean angle.
Edit track map in ACS.
See section in CIQ app documentation.

Remember to start an activity on the Garmin before starting to ride. Aerosensor will automatically create new laps every time you cross the tapeswitch. Note that the data appears on the Garmin a couple of seconds after the end of lap, once Aerosensor has finished averaging data for the lap.

Aero testing guidance

Reliable aerodynamic testing is reliant on good testing protocols. Here are a few tips for best results.

CdA data is only as accurate as the inputs. Make sure you check Aerosensor’s settings in the ACS app before every test.
Always calibrate power sensor before starting testing. Small calibration offsets can result in a big error in CdA measurement.
Always start and end your test block with a baseline repeat.
Try to maintain a constant speed through each run.
For velodrome testing we recommend 6-8 laps per configuration.
The more laps you do, the better the repeatability will be.

Data Analysis

Data is recorded to FIT file. You can view the data via various platforms:

Aeroportal
Our online portal designed to simplify your data analysis.
Aerosensor Excel Analysis Tool
Automated in-depth analysis in a macro-enabled Excel workbook, available from the downloads section.
Aerotune
Online platform tailored for Aerosensor analysis.
See Aerotune website.
Garmin Connect
All Aerosensor data is visible as “Developer fields” on the Garmin Connect website, after your head units has synced.
WKO
Workbook available from downloads section of our website.
Golden Cheetah
We are working with Golden Cheetah developers to better support aero testing. Watch this space!

Device basics

Specifications

Dimensions (H x W x D)	34 x 76 x 76mm
Mass	66g
Battery Life	28 hours
Timing resolution	+/- 1ms

Layout

Power button
LED
Reset button
USB-C charging port
Tapeswitch port

Button functions

Power button:
- Press and release to turn on.
- Press and release to shut down.
Reset button:
- To be used in case the device becomes unresponsive.

LED significance

The multi-colour LED indicates the device state as shown below:

Colour	Flashing	State	USB	Charge
Cyan	Solid	On	Unplugged	Normal
Lilac	Solid	Trigger	N/A	N/A
Amber	Solid	On	Charger	Low
Green	Solid	Off	Charger	Charging
Blue	Solid	On	Computer	Charging
Light blue	Solid	Off	Computer	Charged
Any	Flash	On	Aerosensor connected

Note: Do not use sharp objects or tools to press buttons, this may result in damage.

Important notes & prerequisites

Important notes

Aerodrome uses a Tapeswitch cable as a lap trigger – the cable should not be pinched or bent. Bending with a bend radius less than 4mm will permanently damage the product.

The USB port and Tapeswitch port should be kept dry and free from debris.

Although Aerodrome is splashproof, it is not designed to operate in wet conditions. Please ensure it is not used outdoors when it is raining.

Clean Aerodrome with a soft, dry cloth. Avoid using abrasive materials or harsh chemicals that may damage the product’s surface.

Prerequisites

Aerodrome requires Aerosensor device and a Garmin cycling computer.

Installation

As Aerodrome will likely be used on a live track or a public road, it is critical that you have permission to use the device and/or have taken appropriate measures to ensure not only the safety of you and other riders, but also to prolong the life of the device itself.

The tapeswitch should be placed so that the flat side is against the track or road, and the ridge on the upper side. Using duck tape, secure the tapeswitch across the line the cyclist will be following, be it on the track or the road. Secure at the far ends with tape, and placing a further piece of tape along the length, just holding down the upstream side of the tapeswitch.

Tape along the tapeswitch, not across it (as below).

Aerodrome listens for Aerosensor and the LED flashes when it receives data. It is only able to transmit the lap trigger when this is happening.

For optimal radio performance, make sure Aerodrome is situated in a position where it can receive data from Aerosensor when bike is at or just past the Tapeswitch. It is normally best to position 1-2m downstream of where the lap trigger is placed. Orient the device so that the buttons are closest to the track, as shown in images below.

Plug the tapeswitch plug into the Aerodrome socket and turn on. The power light should illuminate. You can check it is working by pressing on the tapeswitch. The LED will turn purple for 1 second to indicate a lap trigger.

Aerodrome should be placed on the floor well clear of any area the rider is likely to pass. Secure the tapeswitch cable to the floor with duck tape to avoid trip hazards.

Note that currently Aerodrome cannot distinguish between multiple Aerosensor’s running on track. It will only work correctly when a single rider is on track.

CIQ App

Aerodrome Connection

Aerodrome uses Aerosensor, so no specific settings are required in the CIQ App.

Please refer to the Aerosensor section here.

Aerosensor Cycling System CIQ App

Overview

The Aerosensor Aerodynamic Cycling System (ACS) Connect IQ app is required to seamlessly integrate our devices with your Garmin bike computer, providing real-time aerodynamic data and further insights during your ride, and recording your data to a FIT file for further analysis.

Installation

The Aerosensor ACS CIQ app can be downloaded from the Garmin Connect IQ website:

https://apps.garmin.com/

Simply search for “Aerosensor” and the app will come up, or use this link:

https://apps.garmin.com/en-US/apps/0170243b-0384-4072-9e85-57030e4949a6

Install to the Garmin head unit as per the instructions on the CIQ app website.
Start ACS by going to the Connect IQ menu on your Garmin (see Garmin instructions) and then selecting “Aerosensor ACS”.

ACS screen layout

FIT file recording status:
Red square = not recording
Green triangle = recording.
Aerobody connection and battery status.
Aerosensor connection status.
Aerosensor power and speed or speed/cadence sensor connection status:
Green = Connected.
Orange = Searching.
Red = Disconnected.
Aerosensor battery status.
Back key
Use in menus use to go back a step, or on data screens exists app. This may be a button instead of touch screen icon depending on your Garmin Edge model.
Menu key.
This may be a button instead of touch screen icon depending on your Garmin Edge model.

Aerobody CIQ Datafield

Overview

Aerobody is a device that mounts on your stem and measures the distance to your head and chest. This is a good indication of your overall body position.

The Aerobody datafield allows you to view your body position data in the context of your normal Garmin views. You can add it in the same way you would add any other data such as speed, power, time etc. It also adds your aerobody data to the fit file so you can view it after your ride.

Installation

Search for Aerobody on the ConnectIQ store and follow instructions to install.

Once installed, on your Garmin select the data screen (in your chosen activity profile) and edit the field where you want the data to appear.
Select Connect IQ from the list.
Select Aerobody from the list.

Note that aerobody really needs a full screen width field to display correctly as it displays both head and chest positions.

Pairing

Turn on your Aerobody device.

The Aerobody datafield will automatically connect to the first Aerobody signal it picks up. It saves this so that next time it will look for the same physical device.

If you need to switch to a different Aerobody device, firstly make sure that only that one is switched on and in range (roughly 10m) of the Garmin unit, the follow the following steps.

Make sure that Garmin Connect app is installed on your phone and paired with your Edge unit.
Turn on your Garmin and the Aerobody device.
In either Garmin Connect or the Garmin ConnectIQ app, select your device, then go find the datafield app. Open settings.
Move the slider next to “Reset paired device” to the right.
Click “Save”. The display on the Garmin should show “Reconnecting” for 3 seconds then switch back to the data view. Ensure that a surface is within 300mm of the Aerobody device in order to make sure it is reading data.

Setting datum

Aerobody allows you to set a datum, which you can think of as a target position for you to maintain whilst riding. The head and chest fields will go red if you go above this; blue if below, outside of a “null zone”, the dimensions of which you can modify in the settings. You can also set an audible alert to warn you when you are outside of your target range. By default the relative position is shown in the fields, which is the distance between your current position and the datum. This can be changed to absolute position in the datafield settings.
To set your datum, follow these steps:

Get on the bike, ready to get into position. Use a turbo-trainer or friend to support it.
In settings, put the “Set datum” slider to the right. Click “Save”.
On the datafield it will give you a countdown of 3 seconds to get into position.
The datafield It will then average your position and save it.

Now when you are in the correct position the display should have an uncoloured background. If you are too low it goes blue; too high it goes red.

Expected repeatability

aerosensor testing

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Expected repeatability

Outdoors you should be able to achieve the following repetability so long as average wind speed is less than 25% of cycling road speed. If wind speed is above 50% we do not recommend aero testing.

Out-back testing

+/-1.5%

Outdoor velodrome with aerodrome

+/-1.0%

Indoor velodrome with aerodrome

+/-0.5%

For good repeatability careful setup is essential. In particular:

Ensure power meter is calibrated before each run.
Make sure total mass is correct for every run.
Carefully measure the loaded circumference of the wheels (seated roll-out).

Terminology

aerosensor testing

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Terminology

For clarity, its please note the following terminology taht will be used througout this section.

Session

A series of runs covering various bike and rider configurations.

Run

A set of consecutive laps with the bike and rider in a single configuration.

Lap

Either a single track lap, or an “Out” or “Back” leg in out-back testing.

Out Lap

Segment riding at speed away from your starting point.

Back Lap

Segment riding at speed towards your starting point.

Out-back

A pair of consecutive Out and Back Laps.

Baseline

A known starting configuration of bike and rider.

Aerosensor settings

aerosensor testing

Aerosensor settings

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Basic settings

To function correctly, Aerosensor requires the following inputs, entered in the ConnectIQ app here:
Menu → Aerosensor settings → Basic settings:

Aerosensor calibration

Calibration is reported for every run and depends on bike setup. Minor changes (helmet, wheels) have little effect, but adjustments to handlebar height, reach, or sensor position can significantly impact results.

Begin each session with 2 runs and compare reported calibration to the current setting.
If it differs by more than 5%, update it before continuing.

Total mass

Mass affects acceleration, gravity, and rolling resistance, making it critical for accuracy.

Weigh yourself before each session, including bike, gear, and accessories.
Carry fluids on the bike so total weight remains consistent as you drink.
If you refill bottles or use the loo, re-weigh before continuing.

Wheel circumference

Measure the circumference of only the wheel with the speed sensor. This depends on tires, wheels, pressure, and system weight. To measure:

Align a piece of tape on the wheel and ground.
Sit on the bike and roll forward one full revolution.
Mark the new ground position and measure the distance between marks.

Reference Crr (Coefficient of Rolling Resistance)

Find Crr values for your tires and pressure at: https://www.bicyclerollingresistance.com/

Crr depends on road roughness but has a small, consistent effect on CdA measurements.
If testing on a velodrome (wood track), reduce Crr by ~40%.
Example: A road Crr of 0.0035 should be 0.002 on a velodrome.

If unsure the following table shows some typical values for smooth tarmac.

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Tyre Type	Tyre pressure
Tyre Type	60psi	80psi	100psi	120psi
CLINCHER: TT	0.0044	0.0037	0.0033	0.0030
CLINCHER: ALL-ROUNDER	0.0056	0.0047	0.0042	0.0040
CLINCHER: ALL-WEATHER	0.0072	0.0061	0.0055	0.0052
TUBELESS: TT	0.0033	0.0028	0.0026	0.0024
TUBELESS: ALL-ROUNDER	0.0049	0.0042	0.0037	0.0035
TUBELESS: ALL-WEATHER	0.0057	0.0050	0.0044	0.0041
TUBULAR	0.0053	0.0046	0.0042	0.0039

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Advanced Settings

These are settings that you are likely to change less frequently, but nevertheless important. You can find them in the CIQ app here:
Menu → Aerosensor settings → Advanced settings:

Power Meter Scaling

Some power is lost in the drivetrain due to friction (chain, bearings, derailleur, etc.).

Pedal, crank-arm, or spider-based power meters → Set to 0.98 (accounts for ~2% drivetrain loss).
Hub-based power meters → Set to 1.00 (measures power directly at the wheel).

CTF Calibration Offset

For SRM PM7 and older power meters only. Enter the calibration value displayed on your Garmin after calibration (typically ~520).

Time Averaging Period

CdA (not CdA lap) is a rolling average over this time period. It does not affect lap values (e.g., out-back or track testing).

Recommended: 30 seconds (default).

Valid Brake Deceleration

AeroSensor automatically starts a new lap when braking to exclude braking forces from calculations.

Default: 1 m/s²
If using Aerodrome lap trigger: set to 10 m/s² to avoid inadvertently triggering laps for example when going up banking after last lap.

Valid Speed Min

Laps start automatically when speed rises above this threshold.

When testing without Aerodrome lap trigger, set it just below target test speed.
Why? Power meters and speed sensors have small time offsets, which can introduce drag measurement errors if accelerating hard through a low threshold.
Hysteresis: Once speed exceeds the threshold, Aerosensor will not trigger another lap unless speed drops 1 m/s (3.6 km/h) below it.

Braking Time Offset

When braking, Aerosensor discards the last N seconds of data to prevent braking forces from affecting lap CdA calculations.

Recommended: 5 seconds (default).

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Aerosensor Setting Summary

Basic settings

Menu → Aerosensor settings → Basic settings

Setting	Default	Note
Aero device calibration	1.18	Measure yours in testing. Start with 1.4 if unsure.
Total mass	75 kg	Weigh before testing. Includes bike etc.
Wheel circumference	2115 mm	Measure with weighted rollout.
Reference Crr	0.00375	Look up (see table above)

Advanced Settings

Menu → Aerosensor settings → Advanced settings

Setting	Default	Note
Power meter scaling	0.98	Unless using hub based, keep at this value.
CTF Calibration offset	0 Hz	Enter value shown on Garmin after power meter calibration (SRM PM6/7 only).
Time av period	30 s	Rolling average period for CdA
Valid brake deceleration	1 m/s²	Auto lap if brake with deceleration greater than this.
Valid speed min	25.2 kph	Auto lap when speed goes above this value or drops below.
Braking time offset	5 s	Data within this time of braking event is discarded from CdA calculation.

Testing Checklist

aerosensor testing

Testing checklist

Here is a handy checklist to help make sure you are ready to test!

Before Opening CIQ App

Speed sensor paired to Garmin?
Power meter paired to Garmin?
Power meter calibrated?
Power meter auto-cal off (if possible)?

Open CIQ App

Set correct testing type.
Connected to Aerosensor?
Aerosensor paired with speed/power sensors?

Aerosensor Settings

Essentials (Check Before Every Session)

These settings have a major impact on accuracy and must be verified before each test:

Aerosensor calibration set? (Check after 3× out-and-backs; update if >5% off).
Total mass correct? (Weigh before each session; includes rider, bike, and gear).
Wheel circumference measured/set? (Ensure correct value for current tire pressure).
Reference Crr correct? (Adjust for road/velodrome).
Valid speed min set? (Just below target test speed for out-back/track testing).

Less critical (Minimal Impact on Data, Adjust as Needed)

Valid brake deceleration set? (1 m/s² default; 10 m/s² for Aerodrome testing).
Braking time offset set? (Default: 5s).
Time averaging period set? (Default: 30s; only affects rolling CdA, not lap values).

Aerobody Settings (if applicable)

Aerobody connected?
Aerobody datum set?

Session Protocol

aerosensor testing

Session protocol

The testing protocol is the same for all test types.

Aero calibration

It is really important to consider the aero calibration when designing your run plan.

Aerosensor reports a calibration factor for each run to account for airflow slowing as it approaches the bike.

You need to consider the following in order to handle it correctly:

After the first baseline run, update the aero cal in the ACS app.
During testing, if it shifts by more than 5%, update it in the app to minimize altitude calculation errors.
- If this happens in out-back testing, update value then repeat the run.
Expect consistent aero calibration for the same configuration.
Biggest changes occur with body position, stack height, bar angle, etc.

Run plan

Baseline consistency is critical in aerodynamic testing. A known, repeatable configuration ensures accurate comparisons.

Start with two baseline repeats to check system repeatability. Initial drift is common due to power meter offset stabilization and the rider settling in.
End with a baseline run to detect any drift over the session.
Don’t leave more than 10 runs between baselines.

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Run	Configuration	Power meter cal	Aero cal
1	Baseline	Calibrate before run	Last known, or 1.400
2	Baseline (repeat)	Calibrate	Update to calculated
3	First config change.	Calibrate	Keep as last.
4...	Subsequent changes..	Calibrate	Keep as last.
Last	Baseline (final repeat)	Calibrate	Keep as last.

Out-back test protocol

aerosensor testing

Out-back testing protocol

This testing is used when a track is not available.

Road selection criteria

Select a stretch of road, or smooth paved track with the following characteristics:

Traffic: Minimal traffic is best. Aim for fewer than 2 cars per direction per run.
Length: Road should allow 600–1000m of cycling at target speed.
Curvature: Gentle bends are fine, but avoid sections requiring braking or leaning >20°.

Run protocol

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Aim for your target speed, with “Valid speed min” set just below it.
Get into position before reaching this speed.
Around 5 seconds after hitting valid speed, Garmin beeps to acknowledge new lap.
Lap starts when speed threshold is reached.

Ride in Position (600–1000m)

Maintain a steady speed.

Brake Hard to End Lap

Lap automatically ends when deceleration exceeds “Valid brake deceleration”.
The last ~5 seconds of data are excluded from CdA calculation (“Braking time offset”).

Turn Around

Turnaround must take at least 5 seconds to ensure proper lap separation.

Repeat Steps 1–4 in the Opposite Direction

This forms your "Back" lap after completing the "Out" lap.

Complete 3 Out-Back Pairs

Three out-back pairs are recommended because:
- They ensure repeatability of results.
- More data improves accuracy, balancing time vs. quality.

End the Session

After the last Back lap, stop the bike, then press Start/Stop button on Garmin.

Velodrome test protocol with Aerodrome

aerosensor testing

Velodrome testing protocol (with Aerodrome)

This protocol applies to both indoor and outdoor velodromes.

Aerodrome provides highly accurate lap timing (better than 1 ms), generating a separate CdA measurement for each lap. This allows precise tracking of repeatability throughout the session as well as improved accuracy of the data.

Run protocol

You can only test with a single rider on track at any one time.

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

If you are running multiple riders (but only one on track at any one time):

Ensure only 1 aerosensor is switched on. This avoids interference with aerodrome signal.
If using lap logger, ensure only 1 Garmin is running the ACS app. This avoid interference with the lap logger.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Take 1–2 laps to build up to target speed as you normally would.

Start Flying Lap

Cross the lap trigger line at your target speed to begin the first flying lap.

Complete Test Laps

Ride 1,500–2,000m at a steady speed (6–8 laps on a 250m track).
Hold position until you cross the lap trigger at the end of your last lap.

Slow Down After Final Lap

Reduce speed gradually after your last fast lap.

End the Session

Bring the bike to a stop, then press Start/Stop button to end the FIT file recording.

Velodrome test protocol without Aerodrome

aerosensor testing

Velodrome testing protocol (Without Aerodrome)

Without Aerodrome, Aerosensor cannot automatically segment data into laps or identify corner geometry. However, you can still achieve good results by following this method.

Run protocol

You can only test effectively with a single rider on track at any one time.

Before starting, ensure:

ACS app settings are correct, and power meter is calibrated.
Aerosensor ConnectIQ app is running on your Garmin.

Start Activity

With the bike stationary, press Start/Stop button on your Garmin.
Border changes red → green means FIT file is recording.

Accelerate to Speed

Take 1–2 laps to build up to target speed.
Keep speed below "Valid speed min" during this phase.

Start Flying Lap

Aim to accelerate above “Valid speed min” at the start of your first flying lap.
Alternative: Use a Garmin remote lap trigger or the Garmin lap button to manually start the lap when crossing the start/finish line

Complete Test Laps

Ride 1,500–2,000m at a steady speed (6–8 laps on a 250m track).

Decelerate After Final Lap

Reduce power naturally after crossing the start/finish line at the end of your last flying lap.
Alternative: Use the Garmin remote lap trigger to manually end the lap.

End the Session

Bring the bike to a stop, then press Start/Stop button to end the FIT file recording.

Aeroworkbook

aeroworkbook

Overview

Our AeroWorkbook is a macro-enabled Microsoft Excel workbook that enables easy analysis of FIT files generated with the Aerosensor ACS Garmin Connect IQ app.

Its main features are as follows:

Download FIT files from the our AeroPortal cloud server.
Import FIT file data.
Correct parameters.
Add descriptions and notes to each run.
Select valid laps.
Calculate out-back, lap and run averaged data.
Display histograms showing wind variation.

Quick start

For those in a rush, here is a brief overview of how to use AeroWorkbook:

Click on Load FIT files on the Control This loads either from a local directory or the cloud, depending on whether or not you have Use cloud set to True or not. You can load more than one fit file at once.
Files are each loaded into separate tabs in the AeroWorkbook.
On each run tab, select Valid laps by adding or removing an X in the appropriate column. Laps with an X next to them are the laps that will be used for the run calculation.
If required, you can change the values of the parameters used for calculation.
Either click Recalculate Sheet on that sheet, or click Recalculate on the Control worksheet to recalculate all runs.
Final run data is shown in the Summary.

Articles

Installation and Setup

aeroworkbook

Installation and Setup

Download

You can download the AeroWorkbook here:

https://info.aerosensor.tech/docs/start/downloads/excel-tools/

Prerequisites

Since V1.5.5 the FIT files are loaded directly within the Microsoft Excel macros, so Java is no longer required. Similarly the script files which used to be required on mac are no longer needed!

Since there is no longer anything to check on your system the “Check system” button has also been removed.

Checking your system

After carrying out these steps, use the Check System button on the Control worksheet to check that everything is set up correctly on your computer. You should see something like the following. If there is a red x by any item you should check you have done everything correctly.

Setup

Before you load any data you will need to set the aerotool up depending on the testing you are doing. The settings are all on the Control worksheet.

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Basic settings

Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Testing type

Either track or out-back.

Delete raw data

When a FIT file is loaded the raw FIT file data is loaded into worksheets named after each of the 3 data types (record, lap, session). If you want to check the raw data set this field to false. For most purposes you can leave it as true.

Auto calibrate

Aerotool calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Speed units

Select an option from either kph or mph.

Use cloud

Set to true if you want to load data from aeroportal.
Set to false to import locally saved FIT files.

Advanced settings

Most users should not need to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when track testing option selected under basic settings.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Show/Hide definitions

This shows or hides the worksheets where the data definitions are stored. For most users this can be ignored.

Show/Hide log

If aerotool crashes you can show the log and send that information to support@aerosensor.tech for technical support.

Operation

Here is just a quick description of these buttons

Load FIT files

Button opens a dialog to load in FIT files, either file based or aeroportal based, depending on Use cloud settings above.

Recalculate

Button recalculates data for all runs currently loaded.

Reset workbook

Deletes all currently loaded run data.

Check system

Checks the system is set up correctly to enable FIT files to be loaded.

Loading and viewing data

aeroworkbook

Loading and viewing data

Loading data

For each run you load into the excel tool, a separate worksheet will be created named Run_X where X is the number of the run, starting at 1 for the first one you load. It will also create a Summary worksheet showing data for all runs, and two graphs showing the CdA and power variation to your baseline.

File based system

Change use cloud in basic settings to false.
Click on Load FIT files.
Select one or more FIT files from the file system.

Each FIT file will be loaded in turn.

Aeroportal based system

1. Change use cloud in basic settings to true.
2. Click on Load FIT files.
3. Select one or more FIT file then click the Open
If the FIT file has not been loaded before, it will be saved onto your computer.

On windows files are saved to the following directory:
C:/Users/[UserName]/AppData\Roaming\AerosensorExcel

On Mac they are saved to the following directory: /Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Run analysis

There are a few steps to getting the best accuracy from your data.

On the worksheet for each run you can edit any of the cells highlighted yellow.

Select valid runs

Aeroworkbook will automatically mark runs as valid based on the speed tolerance criteria by putting an X in the Valid column of the Lap summary table, highlighted in yellow.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can whether to use auto cal for this specific run by selecting true or false under Auto cal in row 5.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters in the column marked Setting in device and also copied to Used for calibration when first loaded.

If any of these were not correct, or for example you are not using auto cal and want to manually change the Aero Cal value then can change it here.

Recalculate

Either click Recalculate sheet to recalculate data for the active run sheet, or click Recalculate on the Control worksheet to recalculate all runs. The data is recalculated in the run sheets and also updated in the Summary sheet.

Interpreting data

In the summary sheet you see a list of all of your runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the section “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
     $v =$ Speed (m/sec)

Histograms

On each run sheet histograms of headwind and wind yaw angle are shown for all of the laps marked as valid.

For each headwind bucket it shows the percentage of time spent with that level of headwind.
If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.
This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.
For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Editing data

aeroworkbook

Editing data

Creating sessions

Typically you will want to group runs together, for example by test, by creating sessions and then assigning runs to these sessions.

With Use Cloud set to True click on Load FIT files. Log in if requested.

Click on Edit sessions to open the Sessions dialog box.
Click on Create New Session to create a session.
Enter an appropriate name for the session then click Save.

This new session will now be available to assign to runs.

Assigning runs to a session

You can change the session associated with a run by editing the run information as described below. The sessions you created in the step above should all appear in the drop-down menu of the file details dialog.

Editing run information for a single run

With Use Cloud set to True click on Load FIT files. Log in if requested. The following form will show listing all of the runs available. Against each run is shown either Cloud or Local: If Local is shown then you have already downloaded the run locally.
Select a run by clicking on it then either click Edit or right-click on the run. It will open this form.
You can edit the Session, Run Description, Run notes and Used values which are the parameter values that aeroworkbook will use for calculations.
Click Save to update the information in the aeroportal database for that run.

Editing run information for multiple runs

Select multiple runs that you want to edit, then either click Edit or right-click on the runs to edit them.
The same File details form will open as before. Here you can only edit session, and Used values Values that are common for your runs will show in the dialog. Where values differ the associated field in the form will be blank.
Click Save to save these edited values for all runs.

Glossary

aeroworkbook

Glossary

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FIT file data

Fit files have 3 types of data. For each type there will be multiple variables such as power, speed etc.

Record

This is the time series data, recorded at 1Hz: one value per second.

Lap

One value per lap.

Session

One value for the entire FIT file.

Lap or Out-Back Summary Metrics

In the run data there are many columns. Some are self-explanatory but others are explained below.

Dist revs

Lap distance in wheel revolutions.

Av speed

Average speed over the lap = lap distance / lap time.

Yaw

Average wind yaw angle.

Abs Yaw

Average of the absolute yaw angle, where negative values are treated as positive.

Yaw SD

Standard deviation of the 1Hz yaw data over the lap. Indicator of how gusty the wind is.

Headwind

Headwind speed = wind speed resolved along direction of travel, minus wheel speed.

Headwind SD

Standard deviation of the 1Hz headwind data over the lap. Indicator of how gusty the wind is.

Pressure

Ambient air pressure.

Records

Number of 1Hz samples present in the lap.

Cal

Aero calibration value for the lap.

CdA

Lap CdA calcualted by aerosensor using the run parameters in the Garmin.

Head

Head position measured with aerobody.

Chest

Chest position measured with aerobody.

pXXXX

Average power values. Positive averages power in to the bike, negative is power out.

pRider

Average rider power.

pAero

Aero drag power

pGrav

Gravitational power (power used to propel up hill, or gained from going downhill).

pFric

Rolling resistance power

pKin

Kinetic power, i.e. if bike is accelerating then power is consumed by increase in kinetic energy.

pPdyn

Dynamic pressure power – this is basically average of speed x dynamic pressure. CdA = -pAero / pPdyn.

pXXXCor

_Cor suffix denotes values corrected for specified Used for calculation values under Run parameters.

CdAFinal

This is the CdA value corrected for specified run parameters and for the calculated aero calibration if Auto cal is set to true. If Auto cal is set to false then CdAFinal = CdACor.

Spd Mag Droprate

Aerosensor tries to detect where a magnet pass event is missed by the speed sensor. This is the rate of magnet pass “drops”. Should be zero.

Spd ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from speed sensor. Generally not an issue but useful for debugging. There will always be some dropped packets.

Pwr ANT Droprate

Proportion of ANT+ data packets not received by aerosensor from power meter. Generally not an issue but useful for debugging. There will always be some dropped packets.

Run Data Metrics

These are the values shown near the top of the run worksheet.

Laps

Number of laps used for run calculation.

Av Speed

Average speed of all laps.

pRiderCor

Average rider power for all laps.

CdA Final

Final corrected CdA with calculated calibration applied if using Auto cal.

Cal Cor

Corrected calibration factor

CdAF+/-

Maximum lap CdA Final variation from the average, in m2.

CdAF+/-%

Maximum lap CdA Final variation from the average, as percentage of average.

Cal+/-%

Maximum Calibration factor variation from the average, as percentage of average.

Head

Average head position.

Chest

Average chest position.

Yaw

Average wind yaw angle, treating negative values as negative.

Abs Yaw

Average wind yaw angle, treating negative values as positive.

Yaw SD

Wind yaw angle standard deviation.

Headwind

Average headwind speed.

Hwind SD

Headwind standard deviation.

CdA Cor

Corrected CdA but if Auto Cal is used, without calibration factor applied.

FAQs

aeroworkbook

Frequently asked questions

Where are my aeroportal files stored locally?

Normally you shouldn’t need to go there, but in case you do:

Windows

On Microsoft Windows the files are saved locally to the following directory, where [UserName] is your username:

C:\Users\[username]\AppData\Roaming\AerosensorExcel

MacOS

On Mac the files are saved locally to the following directory, where [username] is your username:

/Users/[UserName]/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/AerosensorExcel

Can I work on aeroportal files offline?

Yes!

Make sure you download all the files you need while you are online:

Click on Load FIT files.
Select all the files you need which still have Cloud marked next to them in the list.
Click Download to save those files locally.

You can now load the files through the same Load FIT files dialog.

Note: You can only edit run details whilst online and logged into your aeroportal account.

Aeroportal

aeroportal

Overview

Aeroportal is our online platform designed to simplify your data analysis. You can automatically sync FIT files from Garmin Connect, making them accessible through Aeroportal itself, or our Excel Aeroworkbook.

Its main features are as follows:

Pair your Aeroportal and Garmin accounts for automatic importing and storing of FIT files generated with our ACS Connect IQ app.
Correct parameters.
Add descriptions and notes to each run.
Select valid laps.
Organise your runs into sessions.
Calculate out-back, lap and run average data.
Display histograms showing wind variation.

Important: Only FIT files recorded with our ACS Connect IQ app will be transferred to the Aeroportal server. All other FIT files will be ignored.

Quick start

For those in a rush, here is a brief overview of how to setup your Aeroportal account and view your runs:

After creating an account, pair your Aeroportal and Garmin accounts together, and request a Backfill in the settings page or sync some new runs through Garmin Connect.
Use the File Menu (button with three horizontal lines) to see a table of your available runs.
If desired, create Sessions to organise your runs by pressing the sessions tab in the file menu.
If required, you can change the data parameter values of runs by selecting them and and clicking the Edit button. You can also set their sessions here.
Select all runs you wish to view and click the View button.
Click on a Run in the run list on the left hand side, and select Valid laps in the Lap Summary table under the Laps tab, and click Save Laps & Recalc. Valid laps are the laps that will be used for the run calculation.
Final run data is shown in the Summary item in the run list.

Articles

Layout and Account Setup

aeroportal

Aeroportal Layout

The following screenshots show various components of the aeroportal webpage.

Analysis page:

File Menu:

Open Runs:

Aeroportal account

Registration

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Register here” and complete the registration form.
Check your email for a confirmation link and click it to verify.
You should now be able to login to the Aeroportal.

Resetting your password

If you have forgotten your password to log in to Aeroportal, you can request an email to reset it.

Visit the Aeroportal homepage: https://portal.aerosensor.tech/login
Click “Reset here” and type in the email address associated with your aeroportal account.
Check your email for a reset link and click it.
Type in your new password.
Log in with your new credentials.

Garmin account

Pairing Garmin Account

Login to portal.aerosensor.tech.
On the settings page, under Garmin Integration click the Register with Garmin button.
Log in to your Garmin Connect account when prompted. If you have multiple Garmin accounts ensure you are logged into the correct one.
Follow the on-screen instructions to complete the pairing process.

Unpairing Garmin account

To disconnect your Garmin account from Aeroportal:

Login to portal.aerosensor.tech
On the settings page, under Garmin Integration click the Deregister with Garmin
In the popup press Deregister

To disconnect your Garmin account from Aeroportal via Garmin Connect:

Log in to your Garmin Connect account.
Click your profile logo in the top-right corner, then select Account Settings.
In the left-hand menu, choose Account Information.
Under Aeroportal, click Disconnect.

Backfill (Importing historical data)

After you have paired you Aeroportal and Garmin accounts together, the backfill feature allows you to import FIT files uploaded to Garmin Connect before your Aeroportal and Garmin accounts were paired. Once logged into Aeroportal, go to the “Settings” page via button at top of screen.

Log in to the Aeroportal and navigate to Settings via the top menu.
Under Garmin Integration, find the Backfill Data button.
Use the date pickers to select a start and end date. Note: The selected date range must not overlap with dates already downloaded. If it does, unlink and relink the Aeroportal app to Garmin Connect before retrying.

Click “Request backfill data”. The files will download in the background.
To confirm the import, check the available files either in the Aeroportal file menu or the Excel Aeroworkbook
Note: it can take a few minutes for the files to be pulled across to our cloud servers.

Editing Data and Run Setup

aeroportal

Editing runs

Once you have paired your Garmin account and have some files available on our server, you can set persistent descriptions, notes, sessions and metrics for your runs.

Editing a single run

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Use the Pencil Icon to the right of a run to edit data for the corresponding run.
This will open a new menu which will allow you to edit the Session, Run Description, Run notes, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and will be available for use.

If you want to quickly set/edit a description for a run, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the run you want to edit.
Type your new description.
Click away from the Description to save it.

Editing multiple runs

Editing multiple runs at once is a convenient way to assign a session or change values for the selected runs.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select multiple runs by using the checkboxes on the left and clicking the Edit button to edit the selected runs (e.g. assigning a session to multiple runs).
This will open a new menu which will allow you to edit the Session, Run settings and Used values which are the parameter values that will be used for calculations.
Once Save is pressed, your changes are saved and are available for use.

Deleting one or more runs

Sometimes you may want to delete a run, for example, if you backfilled and have multiple runs that are the same. Note: This is a permanent action and to get these runs back you will have to submit a backfill request with the appropriate dates. We also do not recommend deleting runs that were “Errors” during testing, as we will implement a “Hide Run” option in the future, that will allow your run numbering in sessions to stay consistent.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
Select one or more runs by using the checkboxes on the left and clicking the More button next to Edit and View.
Press the Delete selected button.
Press Yes on the popup.

Editing sessions

Sessions are a way to organise, and group runs.

Viewing/Editing your sessions

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
The table will now list all your sessions, including how many runs are currently assigned to a session.
Use the Create New button to create a new session and set its description.
Use the Pencil Icon on the right of a session to edit it.
You can assign runs to sessions as described in the section above.

If you want to quickly set/edit a description for a session, this can be done within the table.

Toggle the Editable Description slider (On by default for mobile phones).
Click on the Description field within the table for the session you want to edit.
Type your new description.
Click away from the Description to save it.

Deleting a session

Sometimes you may want to delete a session. Note: This will NOT delete the runs associated with that session, but they will instead be set to not belonging to a session.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
At the top of this menu, click the Sessions tab.
Click the Pencil Icon to the right of a session to edit it.
Click the Delete session button.
Press Yes on the popup.

Setup before viewing runs.

Before viewing your available runs there are some settings you may want to check.

Run specific settings

These settings may be modified by following the steps above in “Editing runs”.

Basic run settings:

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Testing type

Either track or out-back. Note: Aeroportal automatically picks up what option you selected when starting the run on the Garmin device and sets it appropriately, but it can still be changed if needed.

Auto calibrate

Aeroportal calculates a calibration value for the run. If you want to use this calibration value to correct the final CdA then set to true. If you want to manually set aero calibration then set to false.

Advanced Run Settings:

Most users should not have to modify these values.

Laptime offset

Aerosensor sends lap information through roughly 3 seconds after the lap ended because of the way it has to average lap data. This allows us to align the data so we can for example calculate wind information for the lap.

Max calibration laps

Only used when the run is set to Testing Type: Track.
In an indoor velodrome you typically start to generate your own tailwind after a few laps. This progressively increases the more laps you do. Since the aero calibration is based on the assumption of zero wind, we only use the first 5 or so laps to calculate the aero calibration.

Device wide settings

These are settings that will be applied to all the runs you view. They are found in the Settings page accessible through the cog icon in the top right corner.

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Valid speed tolerance

All laps where the average speed are within this percentage of the fastest will be marked as valid.

Speed units

Select an option from either kph or mph.

Viewing Data

aeroportal

Viewing your runs

Once you have paired your Garmin account and have some files available on our server, you can view your runs. If needed, you can refer to the screenshots in Layout and Account Setup.

On the Analysis page press the Open File Menu (three horizontal bars) icon.
If you have runs available, they will be displayed in the table.
Select all the runs you would like to view using the checkboxes on the left.
Press the View button on the top right.
After a couple of seconds, all runs will be opened and displayed.
By default, the Summary tab will be displayed which contains a table with information about all currently viewed runs, and charts may be viewed by pressing the corresponding tabs at the top.
You can view individual runs by selecting them from the list view on the left hand side.

Note: You can use the Group by Sessions slider to display runs based on session. You can also open all runs belonging to a session directly from the Sessions tab in the file menu.

Run analysis

There are a few steps to getting the best accuracy from your data.

Select valid runs

Aeroportal will automatically mark laps as valid based on the speed tolerance criteria by selecting the checkbox in the valid column in the Laps summary table.

The Laps summary table can be found by clicking on a run in the list view on the left, and clicking on the Laps tab at the top.
Under the Valid column, you can select/deselect laps to be marked as valid.
Once you are happy with your selection, press the Save Laps & Recalc button, to save your lap selection to our server and recalculate the run. This will also update information in the Summary for all viewed runs. Note: Next time you open this run in the aeroportal, it will be loaded with your valid lap configuration.

Note: If you would like to reset a runs valid laps to its defaults, you can press the Reset Valid Laps button.

A few tips on selecting laps:

For Out-back runs, you need an even number of laps. You should be able to see the out and back pairs.
Check the Distance column to make sure the lap looks correct.
Check the Power column to check you aren’t on a warmup or cooldown lap.
Look at the CdA column to make sure the CdA looks stable. Sometimes in the velodrome the first and last laps can be outliers because getting into or out of position on the bike.

Check if auto cal is appropriate.

Decide if using auto cal is appropriate or not. We will shortly be adding more guidance on this.

You can set whether to use auto cal for this specific run by selecting true or false under Auto cal by following the guidance in the section Editing Data and Run Setup.

Check run parameters

The run parameters entered into the Garmin via the CIQ are shown under Run parameters section of the Summary tab of an open run. “Default” marks the Setting in device and also copied to “Used” for calibration when first loaded.

If any of these were not correct, or for example you are not using Auto Cal and want to manually change the Aero Cal value then you can set it by following the instructions in “Editing a single run”.

Recalculate

When changing values such as Run Metrics, Auto Cal, Test Type etc, you can open the file menu, check that the runs you want to view are selected, and press View again. This will recalculate the files with your saved values, update individual runs and also update the Summary tab.

Interpreting data

In the summary tab you see a list of all of your viewed runs. The final, calibrated CdA is in the column under “CdA Final”.

In the very first column you can select your baseline. This is usually the first of a block of runs, and is the run you want to compare everything else to.

Under the column grouping “Delta to baseline” you see the difference between each run and the baseline. This is the most important section.

CdA shows the difference between each run and the baseline in terms of pure CdA.
Watts shows this difference in terms of power. Since power is a function of speed, you need to select an appropriate speed to calculate the power at.

Aerodynamic power, the power expended purely on aerodynamic drag, can be calculated as follows. This assumes zero headwind.
     $p_{aero} = \frac{1}{2} \rho v^3$
Where:
     $p_{aero} =$ Aerodynamic power (Watts)
     $\rho =$ Air density (kg/m3), typically around 1.2
$v =$ Speed (m/sec)

Histograms

On each run in the main list of runs to the left, histograms of headwind and wind yaw angle are shown for all of the laps marked as valid, under the Charts tab on the top.

For each headwind bucket it shows the percentage of time spent with that level of headwind.

If aero calibration is correct, it should be centred around zero.

For each yaw angle bucket it shows the percentage of time spent with that wind yaw angle.

This is Abs Yaw where negative values are treated as positive as generally we assume the aerodynamics are symmetric, so you just want to see what variation is.

Here, by bucket we mean a headwind or yaw angle range.

For example, each headwind bar is 2kph wide, so the bar at 4kph counts all of the datapoints where the headwind falls between 3 and 5kph.

Aerosensor Lap Logger

aerosensor lap logger

Introduction

The Aerosensor Lap Logger is software that lets a coach monitor data from the ACS Connect IQ app trackside.

The Garmin device running the Connect IQ app transmits lap data continuously via an ANT dongle, enabling a connected computer to display and record results in real time. This immediate feedback helps coaches make quick, informed decisions before the rider leaves the track. The lap end data flow is as follows:

Aerosensor takes roughly 3 seconds to send lap end data after receiving lap trigger because of the lap averaging process.

Important notes

When testing multiple riders in the same session, only one Aerosensor should be powered on. The Aerodrome sends lap triggers to the first Aerosensor it detects after each lap, so having multiple sensors active can cause conflicts.
The Lap Logger receives data from all ACS apps in range, so only one Garmin running the ACS app should be used during testing. Multiple Garmins can confuse the logger and result in inaccurate data. The lap logger will warn you if it detects multiple Garmins running the ACS app.

Installation

Compatibility: The software currently runs on Windows only
Download: Available under the "Live lap viewer" section at: https://aerosensor.tech/pages/downloads
ANT+ Dongle Required: For example, the Garmin dongle: https://www.garmin.com/en-GB/p/10997
Optimal Reception: Use a 2m USB extension cable to place the dongle higher up for better signal quality.

Operation

Launch the Application
- From the Start menu, search for ANT_Lap_Logger or use the desktop shortcut. A main window will appear.

Choose a Save Location
- Click Browse and select a folder to store the log files.
Connect the Sensor
- Click Connect and confirm that “Sensor opened” appears.
- In the Messages window, if the ACS app is open on the Garmin, you should see incoming data packets.
- If no data appears, click Close then Open to reset the connection.
- Packet Details: The first byte is the packed ID, and each complete lap message has three packets starting with “0,” “4,” and “8,” ending with the lap number. Lap data only appears once all three packets have been received.
Start a Run
- Click Reset to clear previous data from the LapData grid.
- Enter the run description in the Description field (editable anytime before stopping the log).
- Click Start log to begin recording data.
Note that if there are laps already showing in the lap logger it will give you the option to delete them all. If you want to keep them simply click “No” and these previous laps will be recorded to your log file also.
Monitor Lap Data
- As each lap arrives, use the Flag checkbox to include or exclude laps. The session data displays the average of all flagged laps.

End the Session

Click Stop log to save the data and close the log file.

Access the Log File

Popout window

Click the open popout button in the main window to open a separate window with larger format text. This can be helpful if you need to see key data from a distance, for example if you as the coach want to stand by the start/finish line and shout out lap times to the rider.

Settings

Application settings can be edited from the File->Settings menu:

Number of laps to use for calibration:
Automatically apply average calibration
CSV file separator

Status indicators

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Connection

Closed: ANT USB device connection is not opened. Click “Open” under “Garmin connection”.
Not receiving: Connection to ANT USB device is open but no data is being received.
Receiving: Data is being received from the Garmin. Note you do not need good reception for the entire lap, only for a couple of seconds or so minimum.
“Multiple Garmins!”: Multiple Garmin bike computers running the ACS app are within range. Please turn off the ACS app on the Garmin not in use.

Latest lap: Lap number of most recent complete lap.
Lap data: Each lap requires 3 “packets” of data. These packets are sent 8 times in sequence.
Lap Status: When the Garmin is first turned out it sends packets with no data. These laps are marked as “Invalid”.

For any support queries, please email us at support@aerosensor.tech.

Aerodynamic basics

aerodynamics basics

What is aerodynamic drag?

Aerodynamic drag is the force of the air acting to slow down a cyclist moving through it.

It is made up of two major components – pressure drag and skin friction drag.

Pressure drag is related to the size and shape of the bike and rider. As you cycle forwards you hit air particles out of the way. These are compressed on impact but then space out as they pass over and past you – the difference between these two air pressures is pressure drag. This is why getting into an aerodynamic position and allowing the oncoming air to flow smoothly around you, reduces your overall aerodynamic drag and makes it easier to cycle.
Skin friction is related to the roughness or texture of the surface on the bike and rider, a smooth (laminar) surface allows air particles to have consistent trajectories (pathlines). A rough (turbulent) surface causes irregular pathlines. Something to note however is surface roughness can be used to keep flow attached longer (for example a textured should on a skinsuit) which increases skin friction drag, but reduces pressure drag (of which is a larger component and therefore can reduce overall drag.

How do we measure aerodynamic drag?

There are five forces acting on a cyclist. Aerosensor works by measuring or estimating forces (or power) from the rider (F_R), kinetic (F_K), gravitational (F_G) and friction (F_F) to find the fifth, aerodynamic drag (F_D).

The sum of these sources (positive) and sinks (negative) plus the aerodynamic drag (sink) must equal zero:

$F_{R} \pm F_{K} \pm F_{G}-F_{F}-F_{D}=0$

Aerodynamic drag is comprised of the product of dynamic pressure (p_Dyn, directly measured by Aerosensor), coefficient of drag (C_d, a constant for a given body position/setup) and frontal area (A). In cycling, the coefficient of drag and frontal area are commonly combined as the term CdA:

$F_{D} = p_{\text{Dyn}} \times C_{d}A$

Combining these two equations gives you a relationship between CdA and the other bike forces:

$C_{d}A = \frac{{F_{R} \pm F_{K} \pm F_{G} – F_{F}}}{{p_{\text{Dyn}}}}$

This is what your Aerosensor calculates in real-time!

Why is aerodynamic drag important?

Although aerodynamic drag increases with speed, friction does not – so at high speeds aerodynamic drag dominates.

Above you can see that at 5kph just 10% of your power goes into overcoming aerodynamic drag, and at 40kph this increases to over 80% – ie 80% of your power is used only to push you through the air.

Say you’re taking part in a flat 40km TT, how can reducing your CdA (and therefore aerodynamic drag) affect your race time?

In this example, reducing your CdA by around 10% can save over 1 minute and 30 seconds. The great news about aerodynamic testing is that you can make huge strides in making yourself faster and/or saving more energy for when it matters.

Aerosensor

Aerosensor won’t turn on

We have a known issue where Aerosensor can become unresponsive.

Make sure device has charge by plugging into USB-C.
Press reset button. You can find instructions on where to find it in the quickstart.

In addition, our device works on a standard 5V power supply. Some laptop/phone charges are “smart chargers” that communicate with device to charge at a higher voltage. These just flat out don’t work, so please try the following:

Try a different power source. A computer USB port is usually a safe bet.
Try a different USB cable, just in case that is the problem. Rare but it has happened that the USB cable isn’t suitable.

If the LED doesn’t come on after this, please reach out to our support team.

CdA not showing (invalid or zero)

It is likely that Aerosensor is not correctly paired to your ANT+ sensors.

BLE/ANT+ sensors transmit as both BLE and ANT+ separately. You may have paired to the BLE sensor. In the Garmin go to the sensor, and check that you are paired to the ANT+ sensor.
Check that the ANT+ power meter AND EITHER speed OR speed and cadence sensor is paired properly. Ensure the sensors are on by rotating pedals/crank/wheel then check pass-pairing (in CIQ app go to Connections->Pass Pairing). When properly paired the SPD and PWR icons in the top right hand corner of the CIQ app will show green.

CdA doesn’t match expectation

There are a few reasons Aerosensor may report an incorrect CdA value.

Check that you have entered an appropriate Aero Calibration factor in the CIQ app (Aerosensor settings->Parameters->Edit Parameters). For instructions on how to get this value see the quickstart guide.
Make sure you have calibrated the power meter.
Make sure that other Aerosensor parameters (in particular Total Mass, Wheel Circumference, Power meter scaling, Reference Crr) are correct.
If using a pedal based power meter, ensure that the crank length is set correctly in the Garmin Power Meter sensor settings.

Aerosensor won’t update

If Aerosensor is not able to connect to the aerosensor updater then it is likely the USB-C cable is power only, not power + data. Try a different cable.

We have also noticed that USB-C to USB-C chargers don’t work for updater for this reason.

Aerobody

Aerodrome

Too many laps

If, when using Aerodrome, more laps are shown than expected, it is likely that you are experiencing drop-outs in the speed sensor.

This means that Aerosensor sporadically auto-laps independent of Aerodrome.

Try moving your magnet speed sensor to the front wheel, this should fix the issue.

Aerosensor Setup

In this video we show you how to setup our cycling aerodynamic drag measurement device, Aerosensor: From unboxing through to testing the setup on a turbo trainer.

Aerobody Setup

In this video we show you how to set Aerobody up on the bike, and use both the ACS Connect IQ (CIQ) app, and the Aerobody Datafield to set it up and view the data.

Excel Analysis Tool

Find out how to use our Aerosensor Excel Analysis Tool, enabling you to get the most of your aerodynamic cycling data and make conclusions about your testing quickly and with confidence.

This video takes you from installation on your Windows or Mac computers, through to loading, editing, and analysing the data.

Demo FIT Files

Out-back FIT file

Download demo FIT file to try out-back analysis using our excel tool and other platforms.

Updated 24th March 2025.

Velodrome FIT files

Demo FIT files. See notes text file for more information.

Updated 24th March 2025.

Garmin Connect IQ Apps & Datafields

ACS App

Aerosensor Cycling System app lets you get the most from our unique system of aerodynamic development devices.

Aerobody Datafield

View your body position as you ride, in the context of your favourite data screens with a datafield dedicated to Aerobody.

Aeroworkbook

aeroworkbook for Windows and Mac

Import Aerosensor FIT files directly to excel, and perform basic out-back and velodrome analysis.

V5.1.9 updated 18th November 2025.

Trackside Lap Logger

Aerosensor lap logger

View and log lap data trackside on a Windows computer.

V1.4.1, updated 13th March 2025.

ANT+ dongle driver

Windows driver for ANT+ USB dongle.

Firmware Updater

Aerosensor Updater for Windows

Update your aerosensor and aerodrome firmware to the latest version using a Windows laptop or desktop computer.

Note: For updating, a USB-A to USB-C cable to connect the device to your laptop/computer is required. If your laptop/computer only has USB-C ports then a USB-C to USB-A adaptor is needed.

Please note that updates are only available for Aerosensor and Aerodrome.

Updated 27th September 2024 to V1.11

Aerosensor Updater for macOS

Update your aerosensor and aerodrome firmware to the latest version using an Apple Mac laptop or desktop computer.

Note: For updating, a USB-A to USB-C cable to connect the device to your Mac is required. If your Mac only has USB-C ports then a USB-C to USB-A adaptor is needed.

A macOS version of 12.4 or higher is required.

Please note that updates are only available for Aerosensor and Aerodrome.

Updated 31st October 2025 to V1.16

WKO Charts

WKO CHART

Chart layout for viewing Aerosensor data in WKO V4 or V5.

(01.11.23 Update)

Note that WKO does not show the lap or session data, only the record data, which is the time history.

CAD Files

The CAD files are provided for free use; however, users assume all associated risks. Aerosensor disclaims any responsibility for loss or injury resulting from the use of these files.

Current Aerosensor stay

Includes stay and fairing, plus assembly.

Updated Aerosensor stay

One-piece stay released February 2024.

Pressure Scanner

AeroDAQ for Windows

Configure and record data from your SC-01 Pressure Scanner with our Windows AeroDAQ software.

Updated 5th December 2025 to V1.0

SC-01 User Manual

Hardware, Software and User Programming Manual for our SC-01 Pressure Scanners.

Updated 5th December 2025 to V1.0

SC-01 Specification

Specification sheet for our SC-01 Pressure Scanners.

Updated 5th December 2025 to V1.0