The Shimano GRX RD-RX812 rear derailleur builds on the success of the RD-RX810 with subtle refinements tailored for gravel and adventure cyclists who demand durability, precision, and adaptability. This 11-speed derailleur integrates Shimano’s SHADOW RD+ clutch technology, which is critical for controlling chain tension on rough terrain, minimizing chain slap, and preventing dropped chains.
The RD-RX812 is designed for a wide gear range compatibility, supporting cassettes from 11-30T up to 11-34T. Its long cage (GS) construction accommodates larger sprockets and provides the necessary chain capacity for gravel setups with either 1x or 2x drivetrains.
🚵♂️ Key Features and Design Innovations
SHADOW RD+ Clutch System:
The clutch mechanism in the derailleur cage adds resistance to cage movement, stabilizing the chain during high-vibration conditions encountered on gravel or uneven roads. This dramatically reduces noise and chain drops, enhancing rider confidence on technical terrain. The clutch can be engaged or disengaged depending on rider preference and terrain type.Refined Link Bushings:
Four fluorine-coated link bushings reduce friction, enhancing shift responsiveness and smoothness while improving durability in harsh conditions.Sealed Pulley Bearings:
The guide and tension pulleys incorporate sealed bearings that help protect against dirt and water ingress, ensuring longevity and consistent performance through muddy or wet rides.Direct Mount Compatibility:
Designed to fit directly onto compatible frame hangers for a clean, secure installation. The direct mount provides better derailleur stability and alignment, crucial for precise shifting in off-road scenarios.Pulley Wheels:
The RD-RX812 features 13T pulleys which reduce friction during chain movement, contributing to efficient power transfer and lower drivetrain wear.
🔩 Technical Specifications
Speed: 11-speed
Cage Length: Long (GS)
Max Low Sprocket: 34T
Min Low Sprocket: 30T
Top Sprocket: 11T
Max Front Difference: 17T
Total Capacity: 40T
Weight: Approximately 252 grams
Chain Compatibility: Shimano HG-EV, HG-X11, optimized for LINKGLIDE chains
Mount Type: Standard direct mount
Cable Housing Included: OT-RS900 (240mm, black) for low-friction shifting
🧰 Maintenance & Use Recommendations
Clutch Setting: Adjust clutch ON for gravel and rough surfaces to reduce chain bounce; switch clutch OFF for smooth road conditions or when running specific drivetrain setups requiring less chain tension.
Regular Cleaning: Maintain cleanliness especially in muddy or dusty conditions to prevent premature wear.
Lubrication: Periodic lubrication of pivot points and pulleys is recommended to maintain smooth operation and extend component life.
Compatibility Checks: Confirm cassette and crankset compatibility to ensure smooth shifting and avoid drivetrain stress.
📦 OEM Package Contents
Shimano GRX RD-RX812 Rear Derailleur
OT-RS900 cable housing (black, 240mm)
Long nose cap for cable routing
Basic instructions for installation
🎯 Ideal Rider Profile
Gravel and adventure cyclists prioritizing durability and drivetrain stability
Cyclocross riders requiring precise shifting under aggressive terrain conditions
Riders using wide-range 11-speed drivetrains who want Shimano’s gravel-optimized clutch technology
