Ratchety drive line
05-30-16, 11:07 AM
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Ratchety drive line
I installed a compact exogram GXP crankset a few months back. Preload is correct, no play in the crank. When I'm out riding it feels smooth. However when I slowly spin the crank by hand I can feel and hear a ratchety sensation. The chain line is slightly off creating friction between the crank and cassette. Bottom bracket is press fit, frame is a giant TCR advanced SL. Any suggestions to improve the chain alignment? Lp
05-30-16, 12:06 PM
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Have you tried the crank rotation without the chain riding on the teeth? With the chain riding on teeth have you tried with the chain on differing cog/ring combos? Is your chain worn? have you looked VERY closely at the chain's engagement with the ring teeth and the der pulleys? Andy
05-30-16, 12:14 PM
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On a derailleur bike, it's normal for new chain sprocket combinations to feel this way when the chain is feeding at any sort of angle (90% of the time on a derailleur system). The chain has inner and outer plates and the outer plates never touch the sprocket, while the inners do. So the chain can move over very slightly and is brought back when the teeth engage the inner link, and that's what you feel (or hear). With break in, the sides of the teeth wear into a smoother engagement "ramp", and lube transferred from the chain helps the process.
For a fixed or single speed bike I suspect that you have chain tension issues. keep in mind that correct chain tension is NO TENSION, and moving the wheel forward a hair will solve the problem.
For a fixed or single speed bike I suspect that you have chain tension issues. keep in mind that correct chain tension is NO TENSION, and moving the wheel forward a hair will solve the problem.
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Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
05-30-16, 12:30 PM
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The chain has less than 1K miles. Chain rings are new, cassette has 4K. I suspected the sensation was an interaction of chain plates and crank. I never have felt the ratchety sensation before. Tks for the input. Lp
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