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Discussion Starter #1
Okay, here's my dilemma; hopefully some of you wrenching wizzes out there will have some advice for me...

I've been riding a 10 spd campy 11-23 cassette on my bike for about 6 months, but as I never use my 23, I decided to switch back to a 12-25 that I used last year (it probably has about 3000 miles on it; and the 11-23 has something along the lines of 2000). When I put the 12-25 back on and adjusted the limits on the rear derailleur, I had a weird clicking noise coming from the rear derailleur (the kind you get when it's not perfectly aligned). I was able to work it out by adjusting the limits a little bit, but the noise is still there when I down shift into the 18 tooth cog (the fifth gear in, I think). If I push the the derailleur towards the wheel while pedaling a little bit the noise goes, and when I'm shifting up from smaller cogs, I don't get the noise. For some reason in the big ring, it's not much of a problem.

Any thoughts? Is it possible I didn't put the cassette on right (although I've installed cassettes before without much issue, so I don't see what I did different this time)? Maybe it's on too tight? Is this combination of used chain/used cassette just fated not to work perfectly? But I figured the fact that it works pretty close to perfectly when I upshift, but not when I downshift might be a problem that other people had encountered.

Hit me with the knowledge people, thanks!

-Mark
 

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Likely need to adjust the barrel adjusters

I suggest you follow the the instructions at the link. It may be that the cassettes are just a little different. Mileage should not matter. The only thing that will do is possible cause issues with chain skip due to worn chain or cassette. The shifting is set by cable tension using the barrel adjusters. The limit screws only set the high and low limits. The barrel adjusters set the indexing for shifting between cogs.

If you were able to adjust it by moving the derailleur, follow the instructions below and you should be fine.

http://www.parktool.com/repair/readhowto.asp?id=64
 

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I'd also ck to see if the chain was the correct or optimal length. Too short & the chain will stretch very tightly when in big/big gears. Too long & the rear der won't be able to take up the slack.
 

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What you have described sounds like a simple cable tension adjustment, there should be no reason to reset the limit screws when changing cassettes.

Al
 

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Discussion Starter #5
Thanks for the input everybody; a little update. I've tried focusing in on the cable tension and what I really have is two pretty noisy gears (the 18 and the 17). When I tighten the tension (which brings my drivetrain to a pleasant purr) the shifting in the big ring goes out of whack. So now I have my limits set and my cable tension worked out so that shifting is perfect in the big ring, perfect in the little ring, with that clicking noise pissing me off in the 18 and the 17. Any other theories? Maybe this differently used chain and cassette combo is just not meant to be?
 

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Power2W8 said:
So now I have my limits set and my cable tension worked out so that shifting is perfect in the big ring, perfect in the little ring, with that clicking noise pissing me off in the 18 and the 17. Any other theories? Maybe this differently used chain and cassette combo is just not meant to be?
Are you sure the cassette lockring is tight enough?

If the chain or cassette are significantly worn this could account for the noise, but 3000 miles on a cassette should not be enough to cause that kind of wear. How about the chain? Have you measured it carefully?

Al
 
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