Testing Protocols

October 22, 2020 in Support

This document outlines the currently avalible test protocols with your AeroPro:

Other protocols are in development but are not yet ready for real-world testing. This document will be updated as supported protocols change and/or are added.

Outdoor Out & Back

An out & back test is performed over a stretch of road where the athlete rides out and then back once per lap over a chosen portion of the road. An out and back session requires a supported power meter and may be performed without a wheel speed sensor. However, our recommendation is to always use a wheel speed sensor to improve the quality of results.

When choosing a test location to perform out and back testing there are several attributes to consider:

  • the road should have low traffic, as vehicles passing by an athlete in the midst of testing will produce fluctuations in the drag measurements due to large disruptions in the airflow;
  • ideally a clear line of sight to ensure the rider’s safety and to allow communication between the athlete and coach/fitter;
  • the pavement should be clear of debris and in good condition (unless these qualities are part of what’s being tested).

The chosen segment must be is recommended to be at least 400m in length; i.e. 800m lap length.

Starting a Test

An out & back test is comprised of the following states:

  • Waiting: the period of time before the coach hits “Start Test”;
  • Go: this phase begins when the coach/fitter taps “Start Test”, and provides the rider 15 seconds to accelerate to a speed greater than 15km/h in order for the test to proceed;
  • Active: the portion(s) of the test when the rider is travelling at full-speed and is the test phase when aerodynamic measurements are being made;
  • Coasting: buffer zone to cleanly transition rider out of the test zone. Rider should stay on target power and in position;
  • Turning: where the rider turns around (180º) and begins acceleration in the opposite direction in preparation for the next Active state.

In the event the rider fails to achieve a velocity of 15km/h during the Go phase, the test state will be set to “None” and the session must be cancelled and started again from scratch.

The coach/fitter and athlete should agree upon the desired number of laps (ie: one Active segment out from the starting point, and one Active segment back) for a test session before beginning. A test can consist of any number of laps.

In the future the coach/fitter will be able to define the start of a test’s active segment by dropping a pin on the map corresponding to the start of the segment, as opposed to requiring a 15s window after tapping the “Start Test” button. This change will be communicated.


Common Questions

How Long Should Laps Be?

A longer lap length means more data is gathered per lap, making the final CdA value more converged (accurate). However, if a course contains steep hills causing the rider to surge or an unsafe location to holding position and power it is best to shorten the lap.

How Many Laps Should Comprise a Test?

Repeatability is of the utmost importance in aero testing. There are a number of factors that can impact the CdA calculation such as power drops, vehicular traffic, or changes in rider position. The “correct” number of laps is determined when you see that the CdA number is relatively constant from lap to lap. With ideal test conditions this usually less than 5 laps . More is always better increasing the confidence in your CdA number. However, as little as 3 laps made be done if variability between laps is low.


Velodrome testing may be performed on either an indoor or an outdoor cycling track. The procedure is relatively straight forward requiring both a wheel speed sensor and supported power meter. Note due to the accelerations experienced at high speeds on the track AeroLab recommends the usage of magnet-based wheel speed sensors for increased accuracy.

The testing procedure is as follow:

  • Pair sensors and set session parameters; configuration, combined weight, wheel circumference, etc.
  • Have the athlete start riding around the track to get comfortable and up to the desired test speed.
  • Once at speed and in position the coach/fitter may start the session from the iOS device as the athlete passes by the start location.
  • At this point the AeroPro will begin to gather CdA data while streaming the athletes power and speed to the iOS device. During this time it is very important that the rider stays in his or her aero position and on target power.
  • After the desired number of laps has been completed the coach/fitter may press end test on the iOS device to finalize the session. Once the session has been ended he or she may signal to the rider that the test is over and to return to the start.
  • Wait until the rider is in close proximity of the iOS device to start the synchronization process. Be careful not to separate the iOS device and AeroPro during the synchronization process otherwise the session may be deemed invalid.
  • Once synchronized navigate to the history view to see the cloud processed results.

It is worth noting that the AreoLink CIQ app is not needed for the velodrome test procedure.

Outdoor Freeride

An “outdoor freeride” is a test in which the rider is able to ride any distance at any speed. It is primarily a mechanism to allow data collection for research & scientific purposes, as opposed to optimizing a rider’s fit.

Still having troubles? Contact support.