Originally Posted by
ofajen
FYI, the last (aero) terms of each formula should be proportional to Vg * Va^2, rather than Va^3.
See, for example,
Cycling: Uphill and Downhill
Otherwise, you would be needing power and doing work to stand still in a headwind.
Otto
Yes. Thanks for that refinement. For most calculations people will assume ground speed and wind speed are the same, but obviously that will be wrong most of the time. That said, the actual wind speed that the rider experiences are hard to determine. My experience based on a large number of time trials is that the wind the rider sees is about 1/3 of what the weather is reporting. "Weather wind" is measured in the wide open and about 30 feet above the ground. Bushes, trees, buildings and simple ground effects all reduce the real speed at bike level.