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Fixed gear - chain/noise/tension question(7 posts)

Fixed gear - chain/noise/tension questionmass_biker
Nov 12, 2002 3:32 AM
On the new old ride (fixed gear I just built up), the drivetrain makes an awful racket when under pressure (i.e. standing on the pedals, starting from a dead stop etc.) - it's as if with each downstroke it protests vocally. No such noise when just spinning along. Chain tension/tightness seems reasonable - tight enough to keep it on the cog, loose enough so that the wheel can turn. Using a standard fixed cog (16T) in rear with a Campy crankset up front (39) and a cheapo (non indexed, not narrow) chain. No kinks, tight spots in chain as far as I can tell, and the chainline is dead straight also.

Any suggestions?

MB
re: Fixed gear - chain/noise/tension questionmicha
Nov 12, 2002 4:05 AM
Most fixed cogs you buy are old technology - very old technology. There's no precise chamfering of the teeth and there's probably some runout. Eventually the chain and cog will mate nicely and the noise under load will diminish.

That's my experience from riding track 20 years ago. Things may have changed since then.
are you using 3/32" pitch chain and cog?Tig
Nov 12, 2002 6:49 AM
Its a basic question that has to be asked since we can't see it. Since the chain ring is 3/32", the rest of the drive train should match and not be 1/2" pitch for the best operation. Also, a wide 1/8" cog won't mate to the modern width derailleur chains. Go to http://www.sheldonbrown.org/fixed-conversion.html and scroll down to Drive Train for help with a few things including chain tension.
Harris partsmass_biker
Nov 12, 2002 7:06 AM
Funny enough, I got the Sovos flip/flop hub I am using from Harris Cyclery (home of Sheldon Brown) about 3 years ago. I think the 16T that I got at the time was standard - don't know if that makes it 1/8" or 3/32" though. It worked okay with my old crank/chain for over a year, but the new crank/chain are definitely causing it some grief, especially under high torque. Perhaps the cheap ($8 no-name) chain is too wide for the crank/cog combo? It seems like it is coming down to a case of matching the cog pitch to the crank pitch and chain width, since all other variables (chain line, chain tension) seem to be okay.

MB
small correction . . .micha
Nov 12, 2002 8:54 AM
Good advice from tig. But pitch is distance between one chain roller and the next. All chains nowadays are 1/2" pitch. What's being discussed is chain width only.

Don't mean to be a jerk, but seeing the word "pitch" used for roller spacing and/or chain width can be confusing.
re: Fixed gear - chain/noise/tension questionbrider
Nov 12, 2002 8:23 AM
Even a well-dialed track set-up is going to make some noise -- just part of the territory. As for tension, you should be able to move the chain up and down about 1/4 inch.
And you're sure the noise isn't coming from your knees? (nm)czardonic
Nov 12, 2002 1:19 PM