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Old 01-21-07, 03:41 PM   #1
svt4cobra6
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derailer contacts large gear on cassette!

Hi I recently bought a new 9 speed sram chain and mavic wheel with a 9 speed SRAM cassette. Anyhow the new cassette has 34 teeth and my old cassette had 32 teeth so when I cut the new chain I left it 1 link longer than the old chain. It shifts ok now except that it seems like the derailer is contacting the large sprocket on the cassette when it is in first gear and sometimes while in second gear, just wondering if there is a way to adjust the derailer or if I have the chain a little too long?
thanks Paul.
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Old 01-21-07, 03:56 PM   #2
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If you look at the Park Tool or Sheldon Brown website on dreailler adjustment, it will tell you about 'B' screw adjustment. It is at the back of the derailler and you screw in to move the mechanism awqay from the cogs. However you may be running a cog that is too big for the der, I am sure somebody else will know the specs if you tell them the model (part number ) of your der.
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Old 01-21-07, 05:27 PM   #3
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Sounds like the chain is too long, but you might try the B tension screw already suggested.
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Old 01-21-07, 05:53 PM   #4
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Hi thanks for the response. I can remove a link on the chain and try it. I tried the B screw on the deral but it did not seem to have enough adjustment. Could be that the cog is too big for the der as suggested.
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Old 01-21-07, 06:33 PM   #5
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I had the same problem on custom setup with a hanger. I just used a longer screw from the local Home Depot. Worth a try before trashing the whole project.,,,,BD
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Old 01-21-07, 07:38 PM   #6
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Quote:
Originally Posted by svt4cobra6
Hi thanks for the response. I can remove a link on the chain and try it. I tried the B screw on the deral but it did not seem to have enough adjustment. Could be that the cog is too big for the der as suggested.
You didn't say what the rear derailleur was but there was a period when the Shimano mountain derailleurs were only rated for a 32 tooth big cog.

Here's another suggestion that doesn't cost anything and might work for you. Remove the "B" adjustment screw completely and screw it back in from the other direction. That'll give you a few more millimeters of adjustment which will probably be enough to solve your problem.
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Old 01-21-07, 08:43 PM   #7
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will give it a try. It is the Shimano Deore XT derailer.
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Old 01-21-07, 08:55 PM   #8
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Double-check your chain length..... As well as the B Tension.
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Old 01-21-07, 10:10 PM   #9
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Quote:
Originally Posted by svt4cobra6
will give it a try. It is the Shimano Deore XT derailer.
Get a SRAM (X7, X9, or X0) drivetrain and not only will you be much happier, but it'll work with a 34 tooth cog. My XT (RD750) broke with less than 300 miles on it, I replaced it with a SRAM setup. When I bought it (last year) I found X9 shifters and rear derailleur for approx. $100 online.

Good luck!
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Old 01-21-07, 11:19 PM   #10
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bigger problems now!

I took out the derailer and then tried to put it back but cross threaded the alum frame. I only when in about a full turn so there is still plenty of good thread but I can not get it to go in straight now. Guess the alum is pretty soft.
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Old 01-22-07, 01:18 AM   #11
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Take that puppy straight to a shop and have them run a tap into that hole, stat.

Last edited by Moose; 01-22-07 at 01:23 AM.
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Old 01-22-07, 06:03 AM   #12
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Sometimes the configuration of the dropout on a particular frame will mean the B screw in ineffective in that the surface on which it bears is at the wrong angle. If lengthening the B screw doesn't work and fitting the screw with a cap of some kind to enlarge it, proves ineffective, then I've built up the surface of the dropout with an arc welder before now to give me the correct adjustment
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