[X-post from another thread "Riding In The Wind."]

I had a steady 10mph north wind this morning so I decided to do an experiment: One way into the wind and then turn around with the wind and compare the power data. For both ways I kept it in the same gear (53x16 I believe), attempted to pedal 20mph and 80rpm, hands in the same spot on the hoods.

Headwind:



Tailwind:



As you can see, it's pretty significant, nearly double the power is required to go the same speed into the wind.