Do I need a short cage or long cage XT/XTR RD? I will be running a 11-32 cassette with compact road crank (50/34). Required capacity is a bit more than the short cage spec from Shimano (37T vs 33T spec). Both can handle 34T max cog. Am I limited to the long cage? This will be high normal (traditional) if it matters.
Rans Enduro Sport, Hase Kettweisel Tandem, Merin Bear Valley beater bike
If it was my bike I'd go with the long cage.
If you size your chain to safely cover the big/big combination, you are going to run out of slack take up in the little/little 2 or 3 gear combinations. If it was just 1 or 2 I might be inclined to take a chance since you don't use those combinations anyway but 3 is definitely one too many for me.
personally, although my example is on a full sus trail bike, i run a medium cage, with an 11-32 cassette and the typical tripple front setup, and if i use granny rin gup front i can only drop as low as 5th on the back before the chain goes slack, i have it like this on purpose, mainly to get more chain wrap in the other gear combo's, and because if i need to go down as far as 5th when in the granny ring i should have already changed up into the middle ring on the front...
this gives me enough room for suspension growth when im using big ring to relativly big (4th and upwards) on the back.
i should use a long cage i suppose, but i get alot less chain slap with a medium, and i only loose the gears im not supposed to use anyways...
in your case id probably go medium cage, and simply not use the extream small-small and large-large gear combo's
Ditto. It'll work on any setup. There's basically no downside, unless you're worried that some über Roadie is going to call you out for using a MTB rear mech but they're gonna do that with the 11-32 "pie plate" anyway
I would venture to guess that it'll be easier to find long cage in LBSs or online anyway.
I have the almost the same setup (48/36 crank) and I am using a Tiagra RD-4500-GS mid cage der. I used all of the B screw adjustment to get the 32 tooth to shift well.
That's because Tiagra is road and its (stated) large cog capacity is 27. XT/XTR as the OP is looking at are MTB which has a large cog capacity of 34.
But that really has nothing to do with what the OP is asking about. He's got the right type of RD in mind. He (rightly) inquires about cage length, and it is applicable to this discussion, because of his front difference, which ties into total capacity of the RD (that is: how much slack the RD has to take up when switching from largest chainring to smallest). He's only slightly exceeding the capacity of the short cage, but since long cage will work with pretty much any front and rear combination, there's really no reason not to get it.