A couple of weeks ago I converted an old Centurion Elite RS to fixed gear to try something different over the winter. I've put about 75 mi on it now. Is it just a fixed gear thing to feel some drivetrain "roughness" through the pedals? My road bike is smooth as glass. The bottom bracket, chainring, chain, and cog are new. I overhauled the rear hub and everything looked OK. The chainline is only about 1mm off and it's adjusted to have about 1/2" slack. Thanks.