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Campy Derailleur Capacity(5 posts)

Campy Derailleur CapacityB2
Sep 19, 2002 9:29 AM
The thread on chain length below got me to thinking about my current setup. I'm using a Record standard cage derailleur and a 13/29 cassette. Technically this exceeds the capacity of the derailleur (30 teeth vs. 27 teeth). I was told by a bike shop that they have set up many bikes with this combnation and have had no problems. Clerance between the derailleur pulley and the largest cog is not an issue. My chain has sufficient tension in the small/small combo and although the chain is snug in the big/big combo, the derailleur seems to have some range of motion left to go. Mind you I don't use the either of these combo's and in fact don't really even use the 26 cog in the big chain ring, except by accident.

Now here's my question(s) - What damage is (potentially) being done? Anyone have experience using this combo? Am I asking for trouble?

Thanks,
Bryan
no damage...C-40
Sep 19, 2002 1:36 PM
Your situation proves that a little extra capacity can be eeked out, if the chain is set to the proper length. As long as nothing binds in the big/big combo you're OK.

Keep in mind that 1" is the minimum increment of adjustment, which is equivalent to four teeth. If you happen to get a frame with a chainstay length that's 1/4 inch different than you current frame, you could end up with an in-beween situation that might not work as well.

I still recommend setting the length by the little/little combo. If the chain has tension in this combo, but still rubs on itself, shifting up one tooth may be enough to avoid the rub. Once again, no problem, since you shouldn't use the little/little combo anyway. If I was using a cassette, within the stated capacity of the derailleur, I'd take out the extra inch, instead. Then you avoid the rub and still have the capacity to handle up to a 13-26.

If you use a 13-29 most of the time, it makes more sense to purchase the proper derailleur next time. The longer cage will work with any of the available cassettes.
no damage...Spunout
Sep 20, 2002 3:47 AM
I use the medium cage with my similar setup, better extra capacity than pushing available capacity.

As for chain length, with a derailleur with enough chain wrap, set the length in the little-little combo, tension 10-15mm AS PER THE MANUAL for the c-10 HD-L chain. Runs quieter in 39-29 with proper tension adjustment.

Also, longer chains wear longer, no?
no better chain life...C-40
Sep 20, 2002 5:34 AM
All of the tension that causes wear occurs in the upper half of the chain. The tension on the lower half from the derailleur spring load is insignificant.

I agree that if you use a 13-29, it's smarter to buy the medium cage derailleur. Don't know why people constantly want to push parts past the recommended limits.
And you know, the 29 already pushes....Stinky Hippie
Sep 23, 2002 3:35 PM
...the limit of the medium cage rear d. which is recommended even for 27 tooth cassettes.