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Discussion Starter · #1 ·
I have a rear shifting adjustment problem. I've got a full campy setup, chorus brifters and FD with centaur rear. The problem is the down shifting. One click often doesn't cause a down shift (smaller cog just so I'm clear). I find I'm having to shift down two cogs, then up one to get the desired one cog downshift. Obviously this shouldn't be happening and is some kind of adjustment issue. I'm also not able to even get into my smallest 12t cog.

I've played with the tensioning acording to my Zinn manual till the cows come home and haven't seen any change. I also double, triple and quadruple checked the limits on the rear der. and they are all spot on.

I was thinking that perhaps there was some energy drink gunk in the BB cable guide and that was restricting movement. So I cleaned that out, and lubed all the cables in the housing with some multipurpose chain lube. Same stuff I use for the chain and pivot points.

Will be the first to admit that my chain is old probably about 3-4000 miles in it. But it was shifting my back up bike just fine before I moved it to this bike after the previous one broke.

Cables and housing were installed new this winter, so only about 1000 miles on them so far. I'm stumped... Any suggestions? This is driving me nuts!
 

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If your chain has that many miles on it, then absolutely change it. In addition, since it has gone so long, you may now need to change the cassette. Once a chain stretches, it wears down cassette teeth much faster. If you change your chain on a regular basis, your cassette will last much much longer. Another possibility is that your rear derailleur hanger is out of alignment. with the bike in the workstand, look at the rear derailluer and chainline from behind. Is it straight up and down? or is is skewed to the side? Bike shops have a tool, called a dropout alignment tool to check this. Another thing is cassette compatibility. Are you running a Campy 8,9 or 10 speed cassette with 8,9 or 10 speed shifters? You can't run 10 speed cassettes with 9 speed shifters, etc. It probably wouldn't hurt to wash out the shifter mechanisms with wd-40, they could be junked up or just need lubed.Hopefully one of these tips may get it working better. Good luck
 

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Discussion Starter · #3 ·
Thanks for the input. The shifters are virtually new, only about 1000 miles on them and no poor weather rides so I'm confident they are not gummed up. I am curious about the der. alignment now that you mention it.

No compatibility issues, its all campy 10s.

Would a bent der hanger bias the shifting one way or another? I ask because upshifts seem just fine, down shifts are where I have the biggest problems.
 

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It's kind of hard to say. But if the hanger is out of alignment, it will definitely cuase unreliable shifting. Another thing to check is the "B" screw, the one that adjusts how close to the cogs the derailleur rides. You may want to play with it to see if it makes a difference. Also, chain length could also be a factor, if it is too long it may cause the derailleur pulleys to swing back too far, impedeing proper function
 

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After you get the new chain, just get out the little manual a that came with the rear derailleur and follow each step to the letter. I have installed I don't know how many rear der's and if I do not go exactly by that little book, something is always out of whack. Just my 2c!
 

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Measuring chain wear

batman1425 said:
Will be the first to admit that my chain is old probably about 3-4000 miles in it. But it was shifting my back up bike just fine before I moved it to this bike after the previous one broke.

Cables and housing were installed new this winter, so only about 1000 miles on them so far. I'm stumped... Any suggestions? This is driving me nuts!
Measure the chain for wear. 24 links (12 inches original length) should be no more than 12 & 1/16" That said, it is not likely a worn chain causing this problem. You should disconnect the cable and see if it will shift to the smallest cog. If not, you either have a poorly adjusted limit screw, a bent derailleur hanger, or a badly gunked up derailleur. If it does shift to the smallest cog, then you need to start over with your set up. See the Park Tool web site for detailed instructions.
 

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humor me here...double check and make sure the cable is routed properly to the "anchor" screw on the derailleur (on the correct side of the screw...if that is wrong thos are exactly the symptoms it displays. Hanger adjustment can too, but the "new cables" line made me wonder
 
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