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Discussion Starter · #1 ·
I plan on putting a larger cassette on my bike for an upcoming very hilly ride. Currently I'm running a 13-23, and I see either a 13-25 or 13-29 available. The 29 would be nice as the only time I will use this cassette is for major hill climbs, the 23 is fine for most of my riding.

My question is, will my short cage derailleur work with the 29? 39/53 up front.
 

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You don't mention brand, but ... my Campy bike has a 53/39 crankset, a 13-29 cassette, and a Centaur short-cage rear der. It's "out of spec" per the capacity chart but it works fine. I can even go big-to-big, although I don't do that deliberately (I have done it accidentally, a few times).
 

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Neither Campy nor Shimano is speced for a 29 tooth rear cog and a "short" cage derailleur (I'm sure there are examples where I am wrong here, so sorry in advance). When you use a triple front they tend to go to long cage. Lots of things will "work" but I usually don't want to mess around with things working that close to my spinning spokes.
 

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EBrider said:
Running Campy Record derailleur
Here is what Ribble says, from Campy:


- Short (202g) for double chainset and sprocket set up to 13-26.

- Medium (205g) for double chainset and sprocket set up to 13-29 or for triple chainset and sprocket set up to 13-26.

- Long (217g) for triple chainset and sprocket set up to 13-29.
 

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the facts...

The fact is that it works better with some frames than others. If you never shift to the big/big, then wrap capacity is not an issue. Depending on the exact length of the RD hanger, you may or may not have problems clearing the 29T cog in the little ring.

The other issue is maximum wrap capacity. If the chainstay length is perfect for this setup, it will gain up to 3T of wrap, compared to a frame with the worst possible chainstay length.

To figure the best chainstay length, go to the Park Tool website, plug in the big ring and large cog numbers in to the "rigorous" chain length formula. If the resulting length is very close to an even number, like 53 or 54 inches, it will work.
 

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EBrider said:
I plan on putting a larger cassette on my bike for an upcoming very hilly ride. Currently I'm running a 13-23, and I see either a 13-25 or 13-29 available. The 29 would be nice as the only time I will use this cassette is for major hill climbs, the 23 is fine for most of my riding.

My question is, will my short cage derailleur work with the 29? 39/53 up front.
Shimano: you can run a 30T cassette on Ultegra short cage with 50/34; ... so a 29 will work
 

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You'll want to tighten your B-screw so it moves the rear pulley away from the larger cassette you are putting on.

The only other issue is chain length. The larger the rear cog gets, the more links you may need to add to the chain. You might be able to get away with a 29 without having to do anything, but it might be tight. I'd just avoid cross-chaining the big ring and the big cog.
 

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Discussion Starter · #10 ·
Thanks everyone.

I went with the 26 since that's the spec from Campy, rather than trying to push it. There are some steep 10-12% grades on the ride, where I'm sure there will be some regret, but mostly less than 8%.
 
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