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Shimano XT Dyna-Sys RD-M780 Rear Derailleur

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Item # SHI0405

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Item # SHI0405


The next level.

The Shimano XT Shadow Rear Derailleur RD-M780 passes along all the great performance of its predecessor, along with a few grams of weight savings. It's a crucial part of the Dyna-Sys 10-speed drivetrain system. Dyna-sys gives you exact shifting and an incredible range of gears for your mountain bike.

The Shadow derailleur design holds a number of improvements over their conventional derailleurs. Firstly, the profile is reduced, meaning the Shadow XT Derailleur is less likely to get knocked around by trees and rocks. Secondly, our favorite improvement is the more direct cable path. Your shift housing can enter the stop on the derailleur without the traditional loop of excess housing that often was the victim of contamination and a source of poor performance.

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 more affordable, and if you've been running XT derailleurs as long as we have, you'll know that you'll get a plentitude of mileage on it with great function.

The Shimano XT Shadow Rear Derailleur RD-M780 is available with two cage lengths -- Long (SGS) and Short (GS). The length of the cage determines the overall chainwrap capacity or 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 chainring configuration (18t difference) plus an 11/36 cassette out back (25t difference). This meets the maximum chainwrap capacity of the long cage derailleur (43t). The Short length cage (GS) has a chainwrap capacity of 35t and could be used for a single or double ring/bashguard set-up as the 11/36 (25t difference) plus the 24/32 chainring (8t difference) does not exceed its range.

Tech Specs

Cage Length:
SGS long, GS medium
Maximum Front Difference:
(long) 43 T, (mid) 35 T
Recommended Use:
mountain biking
Manufacturer Warranty:
2 years

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Here's what others have to say...

Unanswered Question

is the derailer automatic and if it isnt...

is the derailer automatic and if it isnt do you know where i coul;d find one that is

4 5

Precise Shifting

Like the FD-M781 front derailleur, the RD-M780's shifting is precise. The M780 comes in long (SGS) and mid length (GS) versions. I've got the SGS version with the CS-M771 / 11/36t cassette. The GS version reduces the possibility of a large rock taking out your rear derailleur when you ride over one.