Shimano XTR Rear Derailleur - RD-M9120

Name: Shimano XTR Rear Derailleur - RD-M9120
Brand: Shimano
SKU: m2oogpihuc
Availability: InStock

The Shimano XTR RD-M9120 12-speed rear derailleur is engineered for marathon riders and cycle tour...

Best current price£170.99from Merlin Cycles

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Shimano Dark Grey/Black Xtr M9120 Rear Derailleur - 12 Speed - / / Long Cage Sgs / 12 Speed

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Merlin CyclesShimano Dark Grey/Black Xtr M9120 Rear Derailleur - 12 Speed - / / Long Cage Sgs / 12 Speed

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eBayShimano XTR RD-M9120-SGS 1x12 2x12 Spd Super Long Cage Rear Derailleur, NIB

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Leisure Lakes BikesShimano M9120 XTR Shad+ 2 Speed Rear Derailleur SGS Long Cage for 10-45T/Double Ring

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Product Information

Full details

The Shimano XTR RD-M9120 is a high-performance 12-speed rear derailleur designed specifically for marathon riders and cycle tourers who utilize double drivetrain setups. It offers exceptional shifting precision and chain stability through its carbon-fibre construction and Shadow RD+ technology, making it ideal for those tackling diverse mountain bike terrain. While it delivers elite-level durability and smooth operation, users should note that it is specialized for double chainring configurations and requires compatibility with Shimano 12-speed HG+ systems.

All features

Model Part Number	RD-M9120
Brand	Shimano

Extended Product Information

FAQs

Can I use this derailleur with a 1x12 setup?

No, the RD-M9120 is specifically designed for double (2x) drivetrains. Use the RD-M9100 for 1x configurations.

What chains are compatible with the RD-M9120?

This derailleur is designed for use with Shimano 12-speed HG+ chains.

Does this derailleur come with a clutch?

Yes, it features the Shimano Shadow RD+ clutch system to stabilize the chain.

What is the maximum cog size supported?

The RD-M9120 has a total capacity of 41 teeth; consult your specific cassette size to ensure it falls within this range.

How often should I service the pulley wheels?

Clean them after muddy rides and inspect for tooth wear every 1,500-2,000 miles.

Troubleshooting

Ghost shifting or inconsistent gear changes

Check for a bent derailleur hanger and ensure the cable tension is properly set via the barrel adjuster.

Chain slapping against chainstay on rough terrain

Ensure the Shadow RD+ switch is in the 'ON' position and check the clutch mechanism for wear.

Stiff or unresponsive shifting

Inspect the housing and cable for signs of contamination or kinking, and clean the derailleur pivots.

Pros and Cons

Pros

Superior shifting precision under load
Durable carbon-fibre reinforced build
Excellent chain stabilization on rough terrain
Lightweight design for marathon and touring

Cons

Restricted to double drivetrain setups
Requires specific Shimano 12-speed HG+ chain compatibility
Higher investment cost compared to mid-range models

Setup, Compatibility & Care

To ensure peak performance, the RD-M9120 must be installed on a frame with a compatible derailleur hanger.

Setup Steps:

Ensure the b-tension screw is adjusted to provide the correct distance between the upper pulley and the largest cog.
Verify that the chain length is sized correctly for the double chainring setup to avoid excessive slack or tension.
Perform indexing adjustments using the barrel adjuster to align the pulley precisely with each cog.

Compatibility:

This unit is exclusively designed for 12-speed drivetrains using the Shimano HG+ ecosystem. It is not backwards compatible with older 10 or 11-speed systems.

Care:

Regularly clean the pulley wheels to remove built-up dirt. Periodically check the clutch tension on the Shadow RD+ mechanism to ensure the chain remains stable; if chain slap increases, consult a professional to adjust the friction settings.