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Old 09-26-08, 05:54 AM   #1
SoCalledFreeman
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Gears slipping. HELP needed!.

Hi, My bikes gears have started slipping when going uphill, i adjusted the derailleurs to make sure their working OK, then i took the bike in for a full service with new cables etc and got all the gears adjusted perfectly. They carried on slipping, so i looked on the internet and found that it could be the chain or sprockets but their all in good condition.

Sorry for going on about it, but its really annoying me especially as everything is how it should be.
Any help/suggestions wanted...

Thanks,
Alex
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Old 09-26-08, 06:52 AM   #2
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Are you sure the chain and sprockets are in good condition? YOu can tell the chain is worn by the stretch in it, not necessarily by what it looks like. Did you tell the shop you took the bike to that the gears were slipping?
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Old 09-26-08, 07:01 AM   #3
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Sometimes I've encountered problems with gears slipping/chain suck even with components that appear fine; and only by replacing them did the problem resolve. I'm fortunate that I have a bucket of bits lying around that I can play with, and as overturn stated did you communicate with the LBS the nature of the problem?
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Old 09-26-08, 07:08 AM   #4
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Overturn is probably right. To check if you need to replace the chain/cassette, get a measuring tape, and measure the distance between 12 links in the chain, from pin center to center. It should be exactly 12 inches. As chains wear, this increases slightly. 1/16 of an inch in excess is the point where many people replace the chain. 1/8 means definitely replace the chain, and the cogs might be bad too. More than that and you'll almost certainly have to replace both.

My guess is you probably have a solid 1/8" of stretch, and you'll need to replace the chain and the cassette. Note you can't replace just one of them (like the chain, for instance), as the worn one will wear the new part until they mate, and you'll be back where you started.

One unlikely alternative - is the thing changing gears when it slips, or is the chain just moving over the cassette? Does your derailer cable go under the bottom bracket? If it's also shifting while slipping (called autoshifting), it could possibly be gunk under the bottom bracket that's catching the shift cable, which pulls on the derailer when you really mash on the pedals, causing shifting. This is most common on steel frames, because they're flexible.

But check the chain/cassette first, 95% chance that's what it is.
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Old 09-26-08, 03:31 PM   #5
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I had a problem with slippage, even with a new chain and cassette. The problem was a worn middle ring on the crank.
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Old 09-26-08, 04:50 PM   #6
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since there are no picts.--- is this a grip shift?
are these old friction shifters?---- check your alignments yourself--- check if your cables are loose
or do they bind....... a cassette body does slip under load if it has a lot of hard miles...
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Old 09-26-08, 05:55 PM   #7
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Quote:
Originally Posted by SoCalledFreeman View Post
Hi, My bikes gears have started slipping when going uphill, i adjusted the derailleurs to make sure their working OK, then i took the bike in for a full service with new cables etc and got all the gears adjusted perfectly. They carried on slipping, so i looked on the internet and found that it could be the chain or sprockets but their all in good condition.

Sorry for going on about it, but its really annoying me especially as everything is how it should be.
Any help/suggestions wanted...

Thanks,
Alex
New chain, new cassette. If your drivetrain is still skipping after that, new chainrings as well.
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