Originally Posted by slvoid
Are you serious or just trying to make me feel better?
All cranks and rings have this to some degree.
They have to. It does not need to be something out of round by any means.
No mater how round everything is they need to have tolerances that allow some space. It's impossible to make it go away totally, unless you want to hand file each ring to each crank. But then you need to deal with BB bearing slop. The chainring bolts and holes have to be loose fit too to account for tolerances.
The casting for the crank can shrink/or not, a few thou. maybe .010? Maybe more? If the rings are just a little short they might be .005 too small? You can't make them too tight, the rings from one company have to fit on the cranks from someone else, with the tolerances both on the high sides. It could easily be. .015 space one side that's possibly .030 from one side to the other side if you push the ring one side to another. .030 is about the thickness of an earring stud on an earring for pierced ears. That's
plenty to cause the slack/tight problem. The rear wheel parts all have tolerances that could go
against you, or not. That's why Sheldon has his "centering the chainring procedure.
I have a freewheel on one side of my track hub. The freewheel is worse than the chain ring, it moves around like a geared freewheel when you spin the back wheel with the bike in the stand. That's worse than the cog threaded on to the hub. All freewheels including geared do this. But because I centered my Chain ring it's not as bad as it could be on my Fuji.