Hey Cris. Im pretty new to friction so I just bought a kit from bike motor parts, figgurin I would get it up an runnin and then see what works. The drive roller is a flat, knurled cylinder with a freewheel built in to it. I have had this setup on 3 bikes now and the only issue at all, if it even is an issue, is the pressure applied to the tire. Too much and i can feel and hear it in the engine, too little and slippage occurs. Having played with it it is easy to set up now and seems to just stay where I put it. I did put a spacer in the middle of the piviot bolt but other than that the kit works fine. I am also convinced that tire selection is vital . A substantal tire with a beefy road tread and hd tubes as well help keep the pressure on the roller. I have ridden in the rain and even up a hill in the rain. As long as i feather the throttle up gradually i can keep it from slippin.So im gonna just ride it for awile and see what happens...Jeff