Shimano GRX Di2 RD-RX815 (2 x 11Speed)

Digital Precision. Rough Terrain Ready.

The RD-RX815 stands out with its integrated Shimano Shadow RD+ chain stabilizer. This toggleable clutch system prevents chain slap and drops by increasing tension on the cage, ensuring a silent and secure drivetrain over technical descents. Because it is a Di2 component, shifting is managed by a high-torque motor that delivers crisp, perfect gear changes even under heavy pedaling loads or when the derailleur is caked in grit.

Why the RD-RX815 is the Gravel Enthusiast's Choice:

• Shadow RD+ Clutch Technology: Features an on/off switch for the chain stabilizer. When engaged, it virtually eliminates chain movement on rough terrain; when off, it allows for easy wheel removal.

• Instant Di2 Shifting: Experience the speed and accuracy of electronic shifting. With a light tap, the digital signal commands the derailleur to move with sub-millimeter precision, removing the "vague" feeling of mechanical cables in dirty conditions.

• Optimized for 2x Drivetrains: Specifically designed to work with Shimano's gravel-specific 2x11Speed setups, providing a wide gear range for steep climbs and fast descents.

• Massive Cassette Compatibility: Supports a maximum low sprocket of 34T, allowing you to run a 1:1 (or better) gear ratio when paired with GRX cranksets for effortless climbing on loaded bikepacking trips.

• E-TUBE Project Customizable: Connect to the E-TUBE app to customize shifting speed, set up Synchronized Shifting (automatic front derailleur movement), and monitor system battery health.

• Low-Profile Shadow Design: The derailleur body sits closer to the frame, tucked out of harm's way to reduce the risk of impact from rocks, stumps, or trail debris.

Technical Specifications:

• Model: RD-RX815

• Series: GRX DI2 (11Speed)

• Chain Management: Shadow RD+ (Clutch)

• Max Low Sprocket: 34T

• Min Low Sprocket: 30T

• Pulley Bearings: Sealed Cartridge

• Weight: ~287g

• Connectivity: E-Tube SD50 port

The Alegro Perspective: In the shop, we consider the RX815 the "brain" of a high-end gravel build. The clutch is the real hero here. It makes your bike remarkably quiet on gravel roads. If you're currently running a mechanical group and struggle with dropped chains or noisy shifting, this is the single most impactful component you can upgrade. It’s a set-it-and-forget-it piece of tech that thrives on abuse.

Silent Chain Control. Electronic Reliability. Conquer the Backroads with Shimano GRX Di2.