Shimano Deore XT RD-M8100-SGS 12-speed single-chainring MTB rear derailleur - IRDM8100SGS

(7 reviews)

12-speed - Compatible with single chainring and 10-45, 10-51 cassettes

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Rear derailleur clevis

Speed compatibility

Transmission type

Ref : 1859956

€92.99

Price : €158.95

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Based on 7 reviews

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Dérailleur arrière Shimano XT RD-M8100 SGS 11/12 vitesses

Shimano Deore XT RD-M8100-SGS 12-speed single-chainring MTB rear derailleur - IRDM8100SGS

More details In stock

Shimano Deore XT RD-M8100-SGS 12-speed single-chainring MTB rear derailleur - IRDM8100SGS

€92.99

Also available in store

Our opinion

The XT 12-speed rear derailleur is compatible with 10-45 and 10-51 cassettes but ONLY for single chainring drivetrains (there is another model for double chainrings: RD-M8120-SGS).

David G.

Former professional team mechanic

Designed for the most demanding mountain biking conditions, the Deore XT RD-M8100-SGSShimano offers fast, precise and quiet gear changes on 12-speed single-chainring drivetrains. Developed to work with the Shimano 10-51-tooth cassettes, it guarantees a wide range of gear ratios to tackle both long climbs and technical descents.

Thanks to SHIMANO SHADOW RD+ technology, this derailleur minimises chain movement on rough terrain, reducing the risk of derailment and unwanted noise. Its low profile also protects it from impacts with stones and obstacles encountered on the trails. The oversized 13-tooth pulleys improve chain guidance whilst optimising drivetrain efficiency.

With its long SGS cage, the RD-M8100 is specifically designed for wide-range 1x12 drivetrains. It is an excellent choice for replacing a worn derailleur or for improving the performance of a trail, enduro or cross-country bike fitted with a 12-speed Shimano r drivetrain.

Key features

Shimano Deore XT rear derailleur for 1x12-speed drivetrains.
Compatible with 10–51-tooth cassettes.
SHIMANO SHADOW RD+ technology for improved chain stability.
13-tooth pulleys for smoother chain guidance and improved efficiency.
Fast, precise and quiet gear changes.
Low-profile design offering better protection against impacts.
Weighs approximately 284 g.

FAQ

Which cassettes is this derailleur compatible with?
The RD-M8100-SGS is designed for 12-speed single-chainring drivetrains ( Shimano ) using a 10–51-tooth cassette.

What is the SHADOW RD+ technology used for?
It incorporates a chain stabiliser (clutch) that reduces chain flutter, improves drivetrain stability and minimises the risk of derailment on rough terrain.

Is this derailleur suitable for electric mountain bikes?
It is primarily designed for 12-speed non-electricmountain bikes, but can be used on certain compatible e-MTBs in accordance with the manufacturer’s recommendations.

Are the pulleys replaceable?
Yes, the 13-tooth pulleys are replaceable to extend the derailleur’s service life.

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Based on 7 reviews

Cyrille D.
Published May 03, 2025 at 11:34 am

5

Long cage derailleur for single chainring 12 speed (Translated review)
Olivier R.
Published Aug 14, 2024 at 03:11 pm

5

More reliable over time than SRAM GX, easy to adjust. (Translated review)
Ghislain N.
Published Jul 19, 2024 at 04:05 pm

5

Replaced identically because mine took a big branch that bent it. (I had already replaced a plate that can be found as a spare part, but this one was really dead) (Translated review)
Vincent p.
Published Feb 16, 2024 at 07:11 am

5

Excellent derailleur. Metal cage. 2 times cheaper than the XTR which has a more fragile carbon cage (Translated review)
Restoueix j.
Published Aug 11, 2020 at 11:06 am

5

This is the second one. The other one got a stone and went into the spokes. It works well, the adjustment is simple, see the tutorials on YouTube, it stabilizes the settings, good gear. (Translated review)
Stephane T.
Published Aug 05, 2020 at 08:25 pm

5

I replaced my SHIMANO XTR 11v with this Deore XT -8100 SGS 12V following a material upgrade, everything works without any problem. Kudos for the speed of sending bike material (Translated review)
Christophe b.
Published Jun 29, 2019 at 08:28 pm

5

I replaced my SRAM GX eagle 12v directly with the new XT 12v, everything is 100% compatible, no chain length to adjust or shifter to change, only my derailleur is Shimano, the rest is SRAM, these Japanese are too good. Be careful with the cable tightening, there are 2 possibilities (one works, the other does not), finally the smooth gears like in the days when Shimano dominated MTB. 2 times cheaper than an X01 eagle. It's going to hurt... Also, congratulations for the delivery, 3 days in a relay point, it's great, and nice price. I will order again on this site. (Translated review)