Quote Originally Posted by bounceswoosh View Post
I did spin classes for a while at the Y, but stopped. My knees didn't like it; never figured out it if it was the resistance from the wheel, or maybe the angle at which the pedals forced me to clip in.
Other than bike setup, as Zeek suggested, another possible problem I've experienced is when old bikes have crank arms that are warped. Yes, it can and does happen! Those suckers hurt my knees!

Switching to a cleat with a little more float helped too (the shiny SPD - not the one directional kind).