Originally Posted by
Johnny Rad
Get a professional fitting.
It's only going to be guesses from this crowd.
Here's my guess: your cleats are be too far forward.
Good luck.
ill agree it is really hard to fit someone without seeing them on the bike. you can always play with different things. guess would be saddle fore and aft or cleat position. i might even have something to do with form when you are tired. some people will move thier knees further away from the top tube when tired.