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For an upcoming ride I'm considering throwing on an MTB 11x34 cassette to help with the hills. I have a standard, double crankset that I won't be changing.

Rather than get a mountain bike derailler, can I get away with a DA or Ultegra "triple" derailler? I can't seem to track down data on the exact length of their respective cages and compare them.
 

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lavamantis said:
For an upcoming ride I'm considering throwing on an MTB 11x34 cassette to help with the hills. I have a standard, double crankset that I won't be changing.

Rather than get a mountain bike derailler, can I get away with a DA or Ultegra "triple" derailler? I can't seem to track down data on the exact length of their respective cages and compare them.
The maximum recommended sprockets for triple and double mechs is the same. So, neither will accommodate a 34T. I have had a 32 "work" but a 34 would be too much.

The problem is that the top jockey wheel follows a certain diagonal trajectory. On a road mech of any variety it is a shallower angle, following the general shape of a road cassette. On a MTB mech its steeper, to accommodate a wider ratio.

A road triple will handle a wide cassette, but with a 34 it's highly unlikely that the B-screw will let you adjust it to clear the 34 sprocket.

Use a medium cage XT which will work with a 34, but will not be too sloppy with a double.

That way you won't have the jockey wheel and 34 grinding against each other.
 
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