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Rear Derailleur Compatibility Question(4 posts)

Rear Derailleur Compatibility QuestionTNSquared
Jul 27, 2003 5:43 AM
I'm considering running a double crankset (53/39) with an XT 11-32 rear cassette to give me some easier gears for cyclocross and mountain climbs.

I know an XT rear derailleur will work, but I have an extra Ultegra triple rear derailleur and wonder if it will work since I'm really running a double crank. The specs I found for the Ultegra at a couple of websites indicate that it can handle a max chain wrap of 37t, which is sufficient for my proposed set-up. However, the specs also say that the Ultegra can only handle a max cog of 27t.

So my question is whether the max cog size is really a separate limitation from the chain wrap, or do they just provide this criteria to make it easy for people who really are running a triple crank and don't understand how to calculate chain wrap?

Thanks - todd
re: Rear Derailleur Compatibility QuestionRusty Coggs
Jul 27, 2003 6:03 AM
Max cog and wrap are different specs,based on different design parameters. an ultegra 9 speed RD will usually handle a 30 cog,sometims a 32 depending on application.
re: Rear Derailleur Compatibility QuestionLC
Jul 27, 2003 8:26 PM
Ultegra most likely will not handle 32. I could not even get 30 to work. The top pulley will hit the large cog. 28 maybe 29 is about all you can hope to get to work.
Thanks. Guess I'll go with XT to be sure. nmTNSquared
Jul 28, 2003 2:08 PM