Rear derailleurs
Shimano Shimano GRX RD-RX812 Rear Derailleur
Mechanical 1×11 · 40-42T
Compatibility: reviewed
Known specifications can be used by the compatibility engine.
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Evidence and freshness
Technical-source dates and retailer offer checks are separate. A retailer check does not validate compatibility.
Report a correction- Technical review
- Aug 6, 2026
- Compatibility review
- Reviewed Aug 6, 2026
Approved technical sources
- Shimano 2026 GRX component ordering catalogManufacturerSource checked Aug 6, 2026Evidence reviewed Aug 6, 2026
Technical data
Specifications
- Speeds
- 11-speed
- Supported speeds
- 11-speed
- Maximum cassette cog
- 42T
- Smallest cassette cog
- 11T
- Supported cassette combinations
- 11-40t, 11-42t
- Supported front chainrings
- 1
- Maximum front difference
- 0T
- Drivetrain family
- Shimano GRX mechanical 11-speed
- Compatible chain families
- Shimano HG-X11 11-speed
- Shift actuation
- Mechanical
- Frame mounting
- Conventional hanger
- Total capacity
- 31T