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Old 10-04-07, 08:35 AM   #1
telebianchi
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RD adjustment with new compact crank

I recently had a Shimano R-600 compact crank (50/34) installed on my 2003 Fuji cross. This replaced the original Ritchey Cross crank that was a 48/38. The rest of the drive system is all Shimano 105 with a 12-26 9-speed cogset.

The shop did a good job setting things up and it is running smoother than before the change with one exception. When I'm on the big ring, shifts from a larger to smaller cog can take four to six revolutions of the crank. But, when it drops, it drops in quick and locks right in. Shifting from smaller to larger cogs goes quickly.

It does not have this same problem when I'm on the small ring.

I know how to adjust deraileurs if they are over or under-shifting, and setting the hi and lo stops. But I'm not quite sure what to do about this. I could probably bring it back to the shop but that would likely mean leaving it for a day or two for what is probably a three minute tweak.

In case it makes a difference, the cogset is original to the bike and probably has about 4000 miles on it. I replaced the chain about 2000 miles ago. I am getting a new rear wheel a the end of the week, and that will have a new cogset and new chain installed along with it.

Thanks in advance for any suggestions.
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Old 10-04-07, 09:12 AM   #2
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Quote:
Originally Posted by telebianchi View Post
The shop did a good job setting things up and it is running smoother than before the change with one exception. When I'm on the big ring, shifts from a larger to smaller cog can take four to six revolutions of the crank. But, when it drops, it drops in quick and locks right in. Shifting from smaller to larger cogs goes quickly.

Thanks in advance for any suggestions.
If you are referring to cog switches of the RD, IMHO, it sounds like the core wire of the RD shifter cable is binding a little, causing the delayed shift to a smaller cog--the smaller the cog, the less tension there is on the core wire. This doesn't have anything to do with switching cranks from the xc crank to the compact crank, though. It can occur from an accumulation of debris in the RD cable housing and/or a dirty RD over time.

You can help the core wire binding problem by replacing the core wire with a new one, but first '******' out the housings with some teflon spray lube. Before you re-intsall the core wire, but after you've removed the chain and old core wire, use a hex wrench to remove the RD and soak it in some solvent for awhile, clean it up with an old toothbrush, and then re-lube it with the same teflon spray you'll use on the housings (or, whatever you prefer as long as it's light enough to not cause binding in the near future).

Anyway, my 2 cents.
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