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I've heard of chainrings being out-of-round...(5 posts)

I've heard of chainrings being out-of-round...curlupanddie
Mar 24, 2003 8:35 PM
but I'm having a different problem with my tension. my cog is out of round. anyone else have this problem? It's bad enough so that the chain tension can be perfect in one wheel position, but loose enough in anonther to the point that I feel substantial give when I apply backpressure while riding. It's getting pretty obnoxious.

Could the cog be mounted poorly?

btw, it's a 19t soma fabrications.
You sure it's the cog???biknben
Mar 25, 2003 10:49 AM
We had this discussion the other day about eliptical chainrings. Did you see it?
http://forums.consumerreview.com/crforum?viewall@@.efc7b16

I can't see how the cog, being as small as it is, could make a dramatic difference even if it wasn't perfectly round. The chainring mounted off center would be the first thing I'd check.
yep.curlupanddie
Mar 25, 2003 1:43 PM
I'm sure it's the cog. the discrepancy occurs every revolution of the wheel, not of the cranks.
re: I've heard of chainrings being out-of-round...desmo
Mar 25, 2003 3:20 PM
it would be easy enough to check. just clamp a piece steel wire or something to the chainstay so it ends up just touching a tooth of the rear cog. when spinning the wheel there should be only a minute difference in clearence across the wire and each tooth. if it is really out of round then it's junk. send it back or buy a different one.
re: I've heard of chainrings being out-of-round...enginebad
Apr 10, 2003 9:23 AM
could be the cog, but its more likely the hub. shell could be cut slightly off, bearing surface could be slightly off, and more likely, the axle could be bent(unless its a surly hub). i've foolishly bent campy track hub axles before while centering the wheel a little to aggressively. im sure this goes without saying, but if you ride on a bent(even slightly) axle, its likely to cause much more damage to other parts of the bike.