XT Rear D's - The differences?

[LowDown]

Shimano's site shows 8 different part numbers for an XT rear derailleur!
Is there a significant difference in quality or performance because prices are all over the place...Thanks.

[Robert]

I'm not totally sure what all eight different models are, but I will take a swing at this -

XT Shadow - The low profile all mountain RD. It tucks in real close to the frame to avoid contact with rocks. Only available in long cage (IIRC).

XT high normal - This would be the standard, regular XT RD that you are used to seeing. When all cable tension is released, the spring pulls the RD outward, to the highest gear on the cassette. Available in long, medium and short cage (three different part numbers).

XT low normal - A low normal derailleur defaults to the inner most gear on the cassette, or the low gear, when all cable tension is released. This was a little expirement Shimano came up with a few years ago that has never really panned out. Some racers really like it as it is easier to drop gears as a climb gets steeper, then load up high gears quickly when it levels off.
Available in long, medium, and short cage (three different part numbers).

My personal preference in Shimano RDs is the Shadow. Light weight. Seriously fast gear changes. However, I have had two failures of the spring mechanism inside the derailluer, leaving me to walk out both times. Shimano has warrantied the RD both times, but I have since switched over the Sram XO.

[Manningzuki]

XT shadow medium cage DR's do exist. Have one on my rig. Works well.

Long RD if you have 3 rings up front, medium cage if you only have 2 rings up front.

[seandlane]

If you are having to replace your rear derailure, look into SRAM. I switched to running SRAM on all my bikes, and will never use shimano again. From what I have observed, SRAMs are more precise in their shifting than shimano. The only downside is they are a tiny bit noisier than shimano. And if you make the switch you might have to change your shift lever due to SRAM's actuation ratio. Speaking of this, an upside to SRAM shifters is that you use only your thumb, which leaves your index finger free to operate the brake, and manipulate the bars with more force.

Just something to consider.

[HardBodyJut]

I second the SRAM suggestion. I think I have an X9 that came on my Specialized Pitch Pro. it has taken abuse well with non existent maintenance or tuning.

Almost forgot, the two thumb levers is awesome for knarly trails where I like to keep my fingers on the brakes.

[JLToy]

SRAM and Shimano is like the Jeep/Toyota debate it is up to personal preferences. I like the feel of Shimmano better but have no quality concerns either way. Most shifting issues are because of operator, maintinence, and compatability issues.

Now to your question. Shimano will have part numbers for long cage, med, and short. Now we have 9 and 10 speed models in those and then a few reverse pull still being made. I am surprised you only found 8 that they are now making. They are all XT the quality realy is all the same, the main concern is to get the part that is compatable with your dirvetrain.

[hustler905]

SRAM isn't a great suggestion unless your shifters are toast too. Shimano and SRAM pull different cable for each shift, so the rear shifters have to match the derailleurs.

I would just get a Shadow, and match up your number of speeds. If you want to save a couple of bucks, don't rule out SLX. It works great, is a little tougher, and a few dollars cheaper than XT.