The Shimano GRX RD-RX815 rear derailleur brings the precision of Shimano Di2 electronic shifting to your 11-speed drivetrain. Engineered for mixed terrain, it ensures smooth and accurate gear changes, enhancing your ride experience on gravel, trails, or roads. Chain Stabilizer for Quiet Rides: Integrated with a chain stabilizer mechanism, the RD-RX815 minimizes chain slap and provides a quieter, more secure ride. For smoother surfaces, the On/Off switch lets you disable the stabilizer, adapting effortlessly to your riding environment. Optimized for Gravel and Adventure: Designed specifically for gravel and adventure riding, the derailleur is compatible with road cassettes featuring a maximum 34T low sprocket, providing a wide gear range for tackling varied terrain with confidence. Durable and Versatile Performance: Built with robust materials and Shimano's proven engineering, the RD-RX815 delivers reliable performance in challenging conditions. Its rugged design ensures it can handle rough trails while maintaining top-notch functionality. The RD-RX815 supports Shimano's synchronized shifting technology, allowing seamless communication between front and rear derailleurs for optimal gear selection.