I noticed my rear wheel was making a "roaring" sound as I coasted into the driveway the other day. Jacked it up, found a "kink" in the chain at the masterlink. The masterlink seems to be "sticking" to the countersprocket, causing the chain to vibrate ALOT vertically. I've tried everything to get this kink out, nothing helps. Everytime the masterlink comes off the countersprocket, it's kinked. This is a "power master" X-ring chain (or something like that) that I bought about a year ago. Guess I'll either have to buy another one, or put the original chain back on....both sprockets still appear new.