XT Rear Derailuer, long or short cage?

[chuck luck]

Going to purchase an XT rear derailuer but unsure if I should get the long cage or the short cage version. I'll be doing XC mountain bike racing.

 

[ganderctr]

Determine the cage length by determining the total capacity you need. The measurement is the sum of the difference of the highest and lowest crank gears (e.g. on my bike that's 52-30) and the difference of highest and lowest cassette gears (26-12)

My formula would be this: (52-30)+(26-12)

My derailleur needs to have a total capacity of 36. My touring bike, with its 50-36-24 chainrings and 11-32 cassette needs a long cage MTB derailleur.

At any rate, pick the cage based on total capacity, and the shorter cage derailleurs give better shifting performance, so if you can use one and still be within your needs, do it.

 

[chuck luck]

Determine the cage length by determining the total capacity you need. The measurement is the sum of the difference of the highest and lowest crank gears (e.g. on my bike that's 52-30) and the difference of highest and lowest cassette gears (26-12)

My formula would be this: (52-30)+(26-12)

My derailleur needs to have a total capacity of 36. My touring bike, with its 50-36-24 chainrings and 11-32 cassette needs a long cage MTB derailleur.

At any rate, pick the cage based on total capacity, and the shorter cage derailleurs give better shifting performance, so if you can use one and still be within your needs, do it.

Shifting performance is what I'm wanting. Somebody told me to go for the long cage if doing XC riding and short if doing downhill and slalom, did'nt give any reason though. A bike mechanic told me if I'm running a larger than stock big chainring than get the long cage cause it will accomodate the larger ring.
My chainrings are normal size, what comes stock with XT self extracting cranks.

 

[boudreaux]

Shifting performance is what I'm wanting. Somebody told me to go for the long cage if doing XC riding and short if doing downhill and slalom, did'nt give any reason though. A bike mechanic told me if I'm running a larger than stock big chainring than get the long cage cause it will accomodate the larger ring.
My chainrings are normal size, what comes stock with XT self extracting cranks.

What's wrong with whit the OP told you. 'Shifting performance' between the long and short is meaningless, especially if you need the wrap capacity.