I recently bought a new/used wheelset. I installed them after checking the cog and lockring. Installed it, check the chain line/tension; we were a.o.k. jumped on, and thought it was all good. After a few seconds i felt this almost thumping feeling in the pedals, from the rear cog. I havent a clue what it could be. I checked the cog, and it almost seem as though the teeth were bent, but i asked the guy who i bought it from, and he said that he had ridden them the day before, and didnt have an isse. Everything seems fine, i just dont get it. Im going to bring it to my LBS tomorrow, but until them i would like to get the opinion from you guys/gals.