Originally Posted by PenguinDeD

40mph with a minor tail wind? I doubt it. Something tells me that wind was blowing a lot faster than you think.

Overtraining sucks, and I've definatly been there. Your legs burn like hell all the time, your performance decreases, you can feel your tendons pop and creak as you move...its not fun. I've done this on my mtn. bike, as at the time I had no car, and had to bike to work and then to wherever else I wanted to go. It sounds like you aren't over trained, just underestimating the wind's help.