03-09-13, 05:50 AM
On your top video (chain off), your sprocket looks like it's "wandering" from side to side to me, almost as if it's warped - how long have them chain / sprockets been on the bike? Have you had any work done recently eg new tyre / brakes?
Check your wheel alignment / sprocket alignment, and a check of your cush drive rubbers is probably in order too.
Check your wheel alignment / sprocket alignment, and a check of your cush drive rubbers is probably in order too.