Aero Testing

Aerotesting is a means of measuring the total forces that act against a cyclist to then ascertain the Drag Coefficient, or CdA, of the moving object. There are two ways to accurately test the CdA of a moving object: Wind Tunnel testing; and Track Based Aero testing (TBA). Both methods have their advantages and disadvantages, however, we use the TBA technique as this allows us to track the aerodynamics of a moving cyclist in real-time, thereby increasing the external validity of our findings. The TBA method uses a mathematical model of aero testing that is now considered the gold standard in real-time aero testing.

The CdA and absolute power output predict cycling time trial performance almost exactly, especially in flat time trial cycling. These two variables are THE predictive variables of cycling speed. Power tends to be improved through the quality of the training environment; CdA however needs to be accurately measured, adjustments made, then remeasured to ensure you are improving your aerodynamic profile. We accurately measure your CdA and make changes to your structure so you increase speed for no increase in power. We have almost 6 years of experience using this form of software with accuracy and reliability. There are several devices on the market presently that attempt to measure CdA, however, where the results fall down is in the actual testing process. Simply using the devices and inferring accuracy from them is actually highly inaccurate: they are NOT designed for real-world use despite their claims. Aerotesting goes beyond the simple use of a device that equates a CdA figure, to ensure that the testing trials are done accurately and that all environmental variables are accounted for, this generates repeatability in your aerotesting.

The fitting process can take around 4hrs to complete. This is done at the Track, or velodrome, in Midvale. The track allows us to measure precisely all environmental variables associated with cycling movement and ensure we are getting accurate data from our measurement systems.Once you are comfortable riding around the track, we then connect a data logger and wind measurement devices to your bicycle, this works in concert with power metre measurements to formulate a CdA of you in real-time.We then make adjustments to your structure (increase bar height, decrease bar height, fore/aft saddle position, etc.) and measure the effect of these changes on your CdA. We can generally complete between 5-8 runs (changes in your structure) to improve CdA. These changes in Aerotesting structure are also referred to against your own perception of comfort, to ensure the positions are functional to you.

We require you, your bike, any spare parts required to fit the bike, your cycling shoes/clothing, and your racing gear (helmet, wheels, etc.). We may require a power metre on your bike if our devices do not fit. You may wish to test different helmets, wheels, and equipment as well as positional changes to improve CdA. The actual outcome of improving CdA will be unique to you and your anatomy. What improves CdA in one person may NOT improve CdA in the next individual.

Yes, anyone can do Aerotesting. The testing runs are done at around 70-80% of maximum effort, so are not too strenuous. We prefer to test people in pairs as this keeps the cost of track hire lower per person.

The final report outlines each run that we complete and what the corresponding CdA measurement was. You can view an example of the report here (link to ‘Actual CdA Report’ file), in this instance we were able to improve the individuals CdA by 8.3% which resulted in an improvement in 40km Time Trial performance of 96 seconds.