Shimano XT Dyna-Sys RD-M781 Rear Derailleur $89.95
The next level.
The Shimano XT Dyna-Sys RD-M781 Rear Derailleur sees a continuance of its predecessor's long history of precision, durability, and a low overall weight. It's a crucial part of the Dyna-Sys 10-speed drivetrain system, and of course, Dyna-Sys provides the exact shifting and range of gears that your mountain rig needs.
The XT derailleur design holds a number of improvements over conventional derailleurs. Firstly, the profile is reduced, meaning the XT Derailleur is less likely to get knocked around by trees and rocks. Secondly, and our favorite improvement, a more direct cable path. Your housing enters the stop on the derailleur without the traditional loop of excess housing that's long been the victim of contamination and grabby brush. Additionally, the new M781 design features Shimano's Direct Mount system for increased stability and compatibility with thru-axle systems. You'll also find that the M781 uses Shimano's venerable Shadow+ clutch in order to eliminate chain slap. Combined, these two features alone make the XT the ideal rear derailleur for all-mountain riding.
Shimano uses tried-and-true aluminum components in the XT derailleurs. All of the knuckles, linkage plates, and cage sides are made from it. So, while it may lack the wow factor of the carbon fiber-laden XTR Shadow, it's far more affordable. And when you've been running XT derailleurs as long as we have, you'll know that you'll get a plenitude of perfect, functional mileage on it.
The Shimano XT Dyna-Sys RD-M781 Rear Derailleur is available in the color Black and in both a Long and Medium cage length. The length of the cage determines the overall chain-wrap capacity, or more simply put, how big of a tooth difference it can accommodate between the biggest gear and the smallest gear. Total difference can be found with this equation: big ring - small ring + big cog - small cog. For example, the long cage (SGS) option will work with a 24/32/42 tooth chainring configuration (18t difference) plus an 11/36 cassette out back (25t difference). This meets the maximum chain-wrap capacity of the long cage derailleur at 43t. The Short length cage (GS) has a chain-wrap capacity of 35t and could be used for a single or double ring/bash-guard set-up as the 11/36 (25t difference) plus the 24/32 chainring (8t difference) does not exceed its range.
Reviews & Community
What is the difference between the Shimano...
What is the difference between the Shimano XT 786 vs. XT 781?
The 781 version is a non-Shadwo Plus version and does not incorporate the clutch system found on the 786 RD. The clutch system helps to provide more chain tension. firstname.lastname@example.org
Good Product, but wrong description
- Familiarity: I've put it through the wringer
This is a sturdy derailleur. It's not fancy but it gets the job done. When you go through a few derailleurs per season the price on this one does not hurt too bad.
Be aware backcountry has the wrong description of this derailleur. This product does not have the shadow+ clutch. That feature is only available on the XT M786.
- Familiarity: I've used it several times
Installed it yesterday and it runs incredibly smooth! Easy to adjust and looks great.
How much is the shipping weight?, Can you...
How much is the shipping weight?, Can you tell me about the dims of the box?
If there is any component you want to upgrade, it's the rear derailleur. I recently broke my chain (partially) and had to limp it home because I forgot my chain tool. I thought my cogs would have chipped teeth but they stood up to the abuse of running a dinged chain for almost 10 miles.
The spec's say this is for a 10 speed, can...
The spec's say this is for a 10 speed, can you use it for a 9-speed setup?
No, DynaSys 10 speed for Shimano uses a different pull ratio and is not cross compatible with 9 speed systems.
That being said, I have heard of some riders posting on forums about them adding spacers to the 10 speed rear derailleur cable clamp to work with 9 speed shifters. I haven't tried it however.