So I have a problem, I have converted my bike into a single speed, keeping the rear freewheel in-tact. The frame has a horizontal drop out, so that is what I used to tension the chain. My problem is that when I pedal starting out, the chain torques the wheel so that it moves slightly and hits the frame. Once I get moving, the wheel is relatively straight again. Any suggestions? Is there some kind of a stopper I could insert into the dropout so that the wheel doesn't move when force is applied to the chain? Any help is greatly appreciated.