Bicycle Mechanics - What derailer for 11-34 9 speed?

I'm putting together a 9 speed cross/hybrid type thing (single chainring up front), with an 11-34 XT cassette, but I'm not sure what derailer to use. Obvious choice would be an XT, but there are two different types: SGS M760 (long) and GS M760 (short). I have also seen M750s, which presumably is just last years model, yes? Other than the arm length, are they any different? According to Shimano's site, they will both take a 34t cog, the only difference I can see is the 'total capacity' (33 for the GS, 45 for the SGS). Is it the same as road derailers, as in the long is for triples, short is for singles/doubles? Also, do Shimano road and MTB cassettes have the same spline pattern?

The other thing is what shifters can I use? Do MTB and road derailers need the same cable pull? ie Can I use DA indexed barcons? Do XT or LX shifter pods have hinged clamps so I can get 'em off quickly (for occasional singlespeed jaunts)? I haven't decided if I want drop or flat bars, hence the many options for shifters :rolleyes: Are there any quality thumb shifters left or will I have to use a down tube shifter with an adaptor (is Paul the only company that make these, $55 is a bit much)?

Capacity is front range + rear range. With one ring up front, your front range is 0. Rear range is 34-11 = 23, thus capacity for your derailleur should be at least 23. The GS should do the trick.

With XT, last year's model (750) is high-normal, '04 models are rapid-rise. With DA indexed barcons, I'd go with last year's model. I'm not sure about the clamps - have never used XT or LX derailleurs... Paul's thumbies are nice, though. Played with a set last weekend on the Karate Monkey one of the guys at my LBS has. He's running 1x9, thumbies, XT derailleur, 11-32 cassette.

Cage suspension point (at the jockey wheel versus between the wheels) sets the maximum cog size limit, whereas cage length sets the chain wrap limit. Since you need to wrap only 23 teeth, use the short cage for less chain slap, etc. With drop bars, consider ratched/non-index barcons. With flat bars, go with old school thumb shifters which support a friction mode.

What do Rapid Riase and High Normal mean? Both GS and SGS are 'Low Normal' according to Shimano, is that the same as Rapid Rise? Knew I should have stuck to singlespeed :)