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Rear derailleurs
Shimano GRX RD-RX820 Rear Derailleur
Mechanical 2x12-speed · 11-34T / 11-36T
Compatibility: reviewed
Known specifications can be used by the compatibility engine.
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Catalog trust
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 13, 2026
- Compatibility review
- Reviewed Aug 13, 2026
Approved technical sources
- Shimano GRX rear derailleur specificationManufacturerSource checked Jul 31, 2026Evidence reviewed Aug 13, 2026
- Shimano rear drivetrain compatibility C-254ManufacturerSource checked Jul 28, 2026Evidence reviewed Aug 13, 2026
- Y's Road RD-RX820 exact Shimano package identityRetailerSource checked Jul 28, 2026Evidence reviewed Aug 13, 2026
Technical data
Specifications
- Speeds
- 12-speed
- Supported speeds
- 12-speed
- Maximum cassette cog
- 36T
- Supported cassette combinations
- 11-34t, 11-36t
- Supported front chainrings
- 2
- Maximum front difference
- 17T
- Drivetrain family
- Shimano GRX 12-speed
- Compatible chain families
- Shimano HG 12-speed
- Frame mounting
- Conventional hanger
- Total capacity
- 42T