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 is a test in which the athlete rides out and back (which constitutes one lap) on the exact same segment. There are several attributes that make a stretch of road an ideal segment for aero testing:
- the road should have low traffic, as vehicles passing by an athlete in the midst of testing will produce fluctuatons in drag measurements due to large disruptions in the airflow; and
- ideally a clear line of sight to ensure the riders’s safety and to allow communication between the athlete and coach/fitter; and
- 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.
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.
An “outdoor freeride” is a test in which the rider is able to (in theory) 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.
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