Shimano GRX Rear Derailleur RD-RX812 1x11-Speed (Upto 42T Cassette)

SHIMANO GRX - Rear Derailleur RD-RX812 - SHIMANO SHADOW RD+ - 42T max low sprocket - 1 x 11-speed

Based on the technology introduced by SHIMANO with the RX rear derailleurs, the GRX RD-RX812 1x11-speed rear derailleur is characterised by quiet, smooth, precise and reliable shifting, even in the most demanding terrain, thanks mainly to the SHADOW RD+ chain stabilisation system.

For gravel, road and cyclocross use: Shimano GRX 1x11-speed Rear Derailleur RD-RX812

It prevents the chain from hitting and unnecessary movements of the rear derailleur cage, thus ensuring uninterrupted switching performance. In total, the GRX family offers five rear derailleurs, which are used depending on the selection of the cassette and the shift system. The rear derailleurs with short cage (Di2: RDRX815; mechanical: RD-RX810) are used for 11-30T or 11-34T cassettes at ULTEGRA, 105 or TIAGRA level. If you use the 11-40T or 11-42T DEORE XT, SLX or DEORE groups, you will need the long cage rear derailleurs (Di2: RD-RX817; mechanical: RD-RX812), both of which have a specific lever-operated ratio for the road bike. Finally, in a 10-speed setup, SHIMANO's HG500-10 cassettes (11-32T, 11-34T, 11-36T) with the RD-RX400 rear derailleur are used.

SHIMANO's GRX, the first Gravel-specific component family designed for both fast progress and safe bike handling on loose surfaces, is the result of an intensive and extensive research, testing and development process that incorporates information and feedback from countless riders on trails, forest tracks, gravel tracks and asphalt all over the world.

Key Features

• Speed Compatibility: 1x11-Speed drivetrain support

• Max Low Sprocket: 42T cassette compatibility

• Derailleur Type: Long Cage Design for wide-range gearing

• Technology: SHIMANO SHADOW RD+ chain stabilization system

• Chain Stability: Adjustable Chain Stabilizer prevents chain drops and slap

• Terrain Adaptability: ON/OFF Clutch Switch for different riding conditions

• Shifting Performance: Quiet and Smooth Gear Changes on rough surfaces

• Compatibility: Works with Shimano Road Dual Control Levers

• Usage Type: Gravel, Road, and Cyclocross Riding

Product Specifications

• Brand: Shimano

• Series: GRX

• Model: RD-RX812

• Speed: 11-Speed

• Drivetrain Type: 1x Setup

• Maximum Low Sprocket: 42T

• Derailleur Cage: Long Cage

• Technology: SHADOW RD+

• Shifting Type: Mechanical

• Recommended Use: Gravel, Road, Cyclocross

Gravel Performance Optimization

The Shimano GRX RD-RX812 is engineered specifically for gravel riding, where terrain constantly changes and drivetrain stability becomes crucial. The gravel-tuned clutch tension keeps the chain secure during bumpy rides while maintaining smooth shifting performance. This reduces drivetrain noise and minimizes chain movement when riding on loose gravel or rough tracks. The derailleur’s long cage allows riders to use wider gear ranges, making steep climbs and technical trails easier to manage. Combined with Shimano’s proven engineering, this derailleur ensures consistent performance across gravel roads, forest trails, and paved routes without compromising efficiency or control.

Easy Operation / Usage

• Installation: Compatible with Shimano road Dual Control Levers for simple drivetrain integration

• Clutch Adjustment: Use the stabilizer switch to enable or disable clutch tension based on terrain

• Gear Compatibility: Works best with wide-range cassettes up to 42T for 1x gravel setups

• Maintenance: Designed for durable performance with minimal maintenance requirements

Why Choose This Product

• Purpose-built derailleur for gravel and mixed-terrain cycling

• Reliable SHADOW RD+ technology for improved chain stability

• Smooth and precise shifting even on rough surfaces

• Supports wide-range cassettes up to 42T for versatile gearing

• Durable Shimano construction trusted by riders worldwide

• Ideal upgrade for modern 1x gravel bike drivetrains

In the Box

• Shimano GRX RD-RX812 Rear Derailleur