CdA is a Premium member benefit. Unlocking this feature gives you an estimate of aerodynamic efficiency on Activities and Segment efforts. CdA is available on all activities and segment efforts that have power meter data.
What is CdA?
CdA is drag coefficient multiplied by the area of a moving object. By lowering your CdA you can attain greater speeds for the same power input. Lowering your CdA will also dramatically reduce the affect of the the wind on your speed.