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Cassette runs rough in one specific cog!

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Cassette runs rough in one specific cog!

Old 08-25-10, 07:30 PM
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Cassette runs rough in one specific cog!

First time installing a new cassette and new chain on my bike. Everything looks good, except the chain runs rough specifically on the third to smallest cog in the cassette. It's an 11-27T Sram cassette (9 speed), with a compatible Sram chain. The cassette was an "out of box" item, meaning it had been previously installed on a new bike but never used. I'm hoping it's not missing a spacer or something, as the 3rd to smallest is the last cog that's fixed to the larger ones, the inside two are separate pieces. The bike runs rough in only that 3rd to smallest cog. When I shift to one smaller, the roughness is gone.

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Old 08-25-10, 09:26 PM
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Which model SRAM cassette? 9xx?

If you were missing a spacer, it'd be very obvious.

I'd guess there is a bad tooth on the particular cog. Could be it was dropped, or just a manufacturing boo-boo.

Did you say this particular cog is mounted to a carrier, and not a loose cog? If so, the cog is riveted to the carrier and not serviceable. You might want to inspect the cog and look for something odd, like a bent tooth, tooth with a little extra extra, mis-shaped tooth...
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Old 08-25-10, 10:45 PM
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If it's new and unused I'd give it some time. It can't be a spacer or bent tooth or anything like that because the symptoms would be worse. It might be some burrs, or a tiny deviation in RD trim (with good ears you can hear the difference).

Make sure all the basic adjustments are spot on, and ride it a while and it'll probably improve with break-in.
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