[unimog406]

I actually know a fellow who races with a prosthetic leg. I can't say for sure whether its above, or below the knee amputation, but I believe it is above.

I really wish I could be more helpful, I can't even remember the guys name, but he races downhill bikes, and can drop me on most trails. Probably more than this kid wants to get into, but it certainly doesn't seem to slow this guy down at all. He mounted a clipless bracket on the bottom of his prosthetic leg, and while his pedaling is not very powerful, he can still jump, drop and drift with the best of them

good luck figuring something out!