Running Di2 on a gravel bike means one less thing to worry about when the route gets messy — no cable stretch, no gritty housing, no shifting quality falling off two hours into a dusty day. Shimano's GRX ST-RX815 Di2 Dual Control Lever brings that wired electronic shifting into a hood shape built specifically for drop-bar off-road use, pairing 11-speed shifting with a hydraulic disc brake master cylinder in a single unit. Sold individually as left (ST-RX815-L) for 2x front shifting or right (ST-RX815-R) for the 11-speed rear derailleur — you'll need both to run a 2x drivetrain.

The hood shape is where GRX earns its keep versus a road Di2 lever. A raised hood head keeps your hand from sliding forward under braking or when the front wheel takes an unexpected hit, and a recessed finger notch prevents the grip from creeping upward over long rough sections. Anti-slip texture wraps the hood body, and the brake lever blade gets its own anti-slip coating for the moments when your gloves are soaked, dusty, or both. A higher brake lever axis and curved blade shape improve leverage from the hoods, which is where most gravel braking happens.

This is the first-generation GRX Di2 platform, which is wired rather than the semi-wireless setup used in the newer 12-speed RX825. Each lever carries two E-tube ports and connects to a standard Di2 battery and junction box via EW-SD50 wires. E-Tube Project handles button assignment, shift speed, and Synchro / Semi-Synchro shift modes. There's no dedicated sprint shifter port on these levers, so the SW-R610 remote is not compatible — climbing switches like the SW-R9160 or SW-R8160 work through the standard E-tube ports.... Read More