Originally Posted by
unterhausen
SPD has a few degrees of float. I don't think it is particularly difficult to utilize the float, but it's almost not there in comparison to speedplays.. I have knee problems, and it is better with speedplays. But really, I don't use the float much. You get used to them and it no longer feels like you are walking on ice. I remember that feeling from the first couple of times I used them, but it quickly went away.
When I sprinted or put in a hard effort my right foot would rub against my crank arm and my right knee would hurt after the ride. It was only with Speedplay's that I could get a pro bike fit that adjusted the cleats to prevent this from happening by restricting my foot from being able to twist to the left while also retaining some float to the right, to avoid being in a fixed position and allowing for some flexibility but there is no feeling of floating on ice, it feels the same as my SPD's did but with my foot position vastly improved. The net result: no knee issues.
This despite a serious knee injury that pretty much ended my racing in my late 20's. Now I am racing again.