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Old 12-07-14, 08:59 PM
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SirHustlerEsq
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6800 cassette peculiar chain behavior

I have a 2014 Evo with 6800 and recently replaced the chain and cassette. The bicycle rode flawlessly until changing cassettes, now I have this strange chain "skip" or "buck". When I'm pedaling in the 53 and 16 or 17-tooth, the chain makes a ticking noise on each wheel rotation. After a little madness including breaking a sub 100-mile chain, I realized the chain is slightly climbing the lower cassette gear. When I spin the crank backwards, you can more easily see it climb. If I spin 110rpm, the chain bucks and skips a little. I decided to deal with the noise at the suggestion of the bicycle shop who said "11-speed stuff is just really tight" and then I broke a chain early in my first ride through some hills.

This made me pretty frustrated so I put on the old , same model number cassette and it does not make this noise nor cause the chain to climb the lower gear. To eliminate variables, I replaced the RD hanger and had it checked by the shop, it's straight. I swapped cassettes on wheels and it always comes back to the one, new cassette as the noise maker. I removed and re-installed the bottom bracket to make sure the crank mounts as inboard as possible. If I adjust the RD inward just one click, the chain is slow to shift from the 25, 23, and slow to shift down to the 12-tooth.

To summarize:
New 6800 cassette
New 6800 chain
Shop fit and adjusted the stuff
Rode home and the next day with ticking noise and funky chain behavior consistent with today's symptoms
Rode, broke chain on day 1
New chain, noise persists
New RD hanger
RD straight-ness verified by shop
Bottom bracket installation reconfirmed (crank is mounted inboard correctly) by shop
Axle and axle cap are straight and true
Cassette noise only on 16 and 17-tooth cogs
Compared and confirmed inter-gear spacer width consistency from old cassette to new
Gears appear to be flat when laid on a machinist's straight
Any RD minor adjustment inboard causes slow/undesirable shifting
Any RD minor adjustment outboard increases noise and chain skipping
New cassette behaves strangely on both sets of wheels; old cassette works flawlessly on both sets of wheels

https://www.youtube.com/watch?v=TlDU...youtu.be&t=40s
Magic at 0:40

Thanks for taking the time to consider this and be mean to me if I've made a stupid mistake.

Last edited by SirHustlerEsq; 12-07-14 at 09:55 PM.
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