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Chain ring wobble.

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Old 05-22-20 | 07:30 PM
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Chain ring wobble.

I've noticed my Specialized Sequoia's chain ring has a slight wobble to it. It
doesn't seem to affect the way it rides or shifts. It shifts very smoothly. Do you
think this would be corrected if I removed the cranks and turned them 45 degrees on the axle
or should I just leave it alone?
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Old 05-22-20 | 07:34 PM
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I would rotate the chainrings instead of the crank.. It's less less harmful.

If the crank is bent, then it's bent and will wobble no matter what angle you rotate it.

Last edited by branko_76; 05-22-20 at 07:40 PM.
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Old 05-22-20 | 07:40 PM
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Originally Posted by branko_76
I would rotate the chainrings befiore the crank.. It's less less harmful.

If the crank is bent, then it's bent and will wobble no matter what angle you rotate it.
Isn't that true with the chainring also?
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Old 05-22-20 | 07:45 PM
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Originally Posted by robertj298
Isn't that true with the chainring also?
you know, I used to learn by asking questions, lately, it seems I learn more by answering them.

I think you just answered your own question
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Old 05-22-20 | 08:01 PM
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I'd say if it doesn't affect anything, take that blessing and keep on motoring. I've come across a few wobblers and they definitely did affect ride and shifting. Sometimes it's just the chain ring and other times it's the spider arm of the drive side crank. I've found out which (or both) by making a flag-ish shaped piece out of masking tape, sticking it to the seat tube where the tape nearly touches the chain ring (or spider arms) and spin the cranks. If the 'ring is bent, get a new ring. If the spider arm is bent, an ever so slight and gentle persuasion with the 'jaws' of a 12" Crescent wrench around the offending spider arm tab (where the rings bolt to/through) can ease things back. This is a Sheldon recommendation, and one I've used a few times to good effect. I'd rather not do it, but cranksets bend sometimes. As always, you do this operation at your own risk. And like I said before, if it ain't messin' with anything, let sleeping dogs lie.
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Old 05-23-20 | 02:03 AM
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Originally Posted by robertj298
I've noticed my Specialized Sequoia's chain ring has a slight wobble to it. It
doesn't seem to affect the way it rides or shifts. It shifts very smoothly. Do you
think this would be corrected if I removed the cranks and turned them 45 degrees on the axle
or should I just leave it alone?
I think if you actually managed to get the cranks on after turning them 45 degrees they would very likely not be square on the axle. You'd probably need a sledge-hammer to do it.

The proper way to get rid of chainring wobble is to remove the ring and make it flat by itself, then re-install it. If it's not the ring that is wobbling then the crank arms or axle are likely bent - again, remove, fix, re-install. Rings are easy, usually stamped from sheet and bendable; cranks are difficult - good aluminium ones don't bend at all easily, much more likely to break instead (straightening steel cranks is a doddle). A bent axle is best replaced, unless you have a set of V-blocks and a hydraulic or good big lever press, a dial indicator, and a way to mount the axle between centres to check runout - got a lathe?

Last edited by oneclick; 05-23-20 at 02:08 AM.
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Old 05-23-20 | 07:09 AM
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Old 05-23-20 | 08:16 AM
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Is it a wobble or is it a non-round chainring? Like Biopace or Ovaltech?

The bigger rings are sometimes difficult to tell if they're non round- I just remember the first time looking down and seeing that.

I also remember a thread here where someone was aghast that a company would put out rings that went out of round.
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Old 05-23-20 | 01:13 PM
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Probably not your problem on that pretty bike Robert, but I had some abused crank arms that I purchased at a bike co-op that had too much wobble. I think the square tapers were bad, and different rings and such would not make them useable. I tried what you mentioned, although, I am sure you meant to rotate 90 degrees with no luck. Perhaps you have tried this, and I think Sheldon Brown advises this.

i am now reluctant to take the cranks off too many times for fear of distorting things. If possible, I make an index mark with a marker so as to put back on in the same orientation. I just installed my first sealed BB, so those cranks shouldn’t have to come off for a long time I hope.
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