well i dont know much about them as i dont ride front freewheel so if the bash is only 4mm wide how can that make the freewheel rub on the frame,front freewheels iv seen have had loads or room between the frame bb so surly you dont need new cranks to run the bash, just a new bb if your unlucky edit i read a post by adam read a while ago, summit about the threads being stripped because of this, or is that a different problem