I am trying to track down an issue with my drive train that I've been trying to fix for a few weeks. I have a single speed setup with freewheel and a bash guard, 34:17 ratio. My chain seems to be catching/dragging somewhere as when I back pedal there is some resistance. My chain is not too tight, I've set up plenty of singles to get this part right. My bash guard was rubbing my chain slightly so I got a 4.5mm wider BB to help correct my chainline. That has not fully solved the problem and I think I will need to space the bash guard 2mm away from the chainring, this should solve the rubbing at the crank end of the equation.

I am also seeing that the freewheel seems to catch a little on each rotation as evident that the chain does a little jump while freewheeling. I have noticed a similar problem on another freewheel (AC Racing 15T) that I used on another build. When I replaced the freewheel with a no name 16T it solved the problem. My current setup has a Shimano 17T that is having the problem as well as a new AC 15T that exhibits the same behavior. I cant imagine that it could be the hub because they are both threaded on opposite sides and having the same issue. The hub spins perfect without the chain and it is brand new. Two bad Freewheels? Any ideas? Something I am missing here?