Power Grips are an excellent product and I've used and recommended/sold them to customers for 15 years. The key to optimum performance, especially on a fixed gear bike is to do the following. Once you've got the strap adjusted where you want, mark it, remove the strap and set the clip aside, use a hole punch to make a hole through the folded strap a bit smaller than the fixing bolt, drill a fixing bolt size hole opposite the threaded hole in the mounting plate, replace the strap, insert the bolt through the new hole and through the hole in the folded strap and screw it into the threaded hole (I sometimes use a bit longer bolt and put a lock nut on it). This modification takes about thirty minutes and improves the reliability and performance of the Power Grips.