When is "round" not round??- Mtbr.com
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  1. #1
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    When is "round" not round??

    I just installed an LX crank with surly 32-tooth ring on my SS. Heard a groaning sound from the drivetrain. Chain was super tight. Loosened my skewer to make sure the wheel was in properly, checked the wheel alignment. Chain tension had about 1/4" play... started pedaling, and got the groan again. I stopped, turned the crank with my hand, and could see the chain tension increase and decrease. Thought the ring may have been deformed from a hit, but it looks OK, and I didn't see any bent teeth when I installed it. My son ran it for a long time as a 1x9, so he wouldn't have noticed any irregularities necessarily. Any thoughts? Big thing is I just replaced the old crank because it was seemingly bent in every possible direction, from which I still have no explanation. Had just recently installed a King 20-tooth cog.

    Gremlins??

  2. #2
    Downcountry AF
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    not uncommon at all. could be that the chainring is not centered on the crank spider. that's one thing that usually has tons of slop and if your not paying close attention it will end up off center.

    look at the tabs where the chainring mounts (stand offs?) and check to see if there's an even gap on all 4 (4 bolt crank right?).

    could also be the crank spider, the chainring, a bent crank axle? could be a gargoyle?

    I would pop the chain off, loosen the chainring bolts, center the ring perfectly and slowly tighten bolts checking it as you go so it doesn't move. put the chain back on and see if it's better. if not, at least you can check that off the list of possibilities.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  3. #3
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    Normal. Set the tension for the tightest spot. You can try loosening the chainring, rotate to the tight spot and retighten to reduce the irregularity.

  4. #4
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    Thanks for the suggestions. The ring was installed by my 16 year old, and sometimes it appears that haste is the order of the day. I start by loosening and retightening the ring.

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