CdA combines the aerodynamic drag coefficient of the rider and bicycle with their frontal area. A lower CdA generally means less aerodynamic resistance and, all else being equal, greater speed for the same power output.

Exercise Institute uses a mathematical track-based testing model to assess the aerodynamics of a cyclist while moving. Track testing enables us to observe changes under real riding conditions while closely monitoring the relevant environmental and performance variables.

Power can be developed through training, but aerodynamic improvements need to be measured directly. A position that looks fast is not automatically faster, and a change that benefits one athlete may not benefit another.

We measure your CdA, make controlled changes and then repeat the test to determine whether those adjustments have produced a genuine improvement. The goal is to help you increase speed without requiring an equivalent increase in power.

The quality of aero testing depends on more than the measuring device. A repeatable protocol, controlled trials and proper accounting for environmental variables are essential to producing useful results.

The track enables us to monitor the environmental variables associated with cycling movement and collect repeatable data from our measurement systems.

Once you are comfortable riding on the track, a data logger and wind-measurement devices are connected to your bicycle. This information works alongside power-meter measurements to calculate your CdA during each run.

We then make controlled adjustments to your setup. These may include changes to handlebar height, saddle height, fore-and-aft saddle position or other relevant elements of your riding position.

We can generally complete between five and eight runs. Each aerodynamic result is considered alongside your perception of comfort and control so the final position remains functional for you as an athlete.

You will need to bring yourself, your bicycle, cycling shoes, cycling clothing and any spare parts required to adjust the bike. You should also bring your intended racing equipment, including items such as your helmet and wheels.

A compatible power meter may be required if Exercise Institute's measurement equipment cannot be fitted to your bike.

You may choose to compare different helmets, wheels or other equipment alongside positional changes. The outcome is individual: equipment or positions that improve one athlete's CdA may not improve another athlete's result.

Testing runs are generally completed at approximately 70–80% of maximum effort, so the session is controlled rather than an all-out physical test.

You must be sufficiently comfortable and competent riding your bicycle around the track. Exercise Institute generally prefers to test athletes in pairs because this reduces the track-hire cost per rider.

The report enables you to compare your baseline against the positions and equipment combinations tested during the session. This provides a clear record of what improved your result and what did not.

In one previous Exercise Institute testing example, the athlete's CdA improved by 8.3%. The modelled effect was a 96-second improvement over a 40-kilometre time trial.

Individual results will vary according to the athlete, their starting position, their anatomy, the equipment tested and their ability to sustain the resulting position.