Shimano GRX BL-RX812 Sub-Brake Levers

These are auxiliary levers designed to be mounted on the tops of your drop bars. They provide an additional braking point, allowing you to control your speed while riding in an upright position rather than having to reach down to the hoods or drops.

These levers are designed specifically for Shimano hydraulic systems. They are compatible with most GRX hydraulic calipers, such as the BR-RX810 and BR-RX400, but they must be installed in-line with your existing hydraulic hose setup.

Installation requires cutting your existing hydraulic brake hose to insert the lever in-line. Because this involves opening the hydraulic system, you will need to bleed the brakes afterward using Shimano's funnel bleeding system, so it is best suited for those comfortable with hydraulic maintenance.

Yes, the BL-RX812 features tool-based reach adjustment. This allows you to customize the lever position to better fit your hand size and braking preference.

The BL-RX812 is designed to be mounted on the top section of your handlebars and is generally universal in terms of orientation, but you should confirm your specific hydraulic hose routing needs before purchase to ensure the hose joint aligns correctly with your setup.

When installed correctly, they act as an extension of your existing hydraulic circuit. They do not negatively impact the power or modulation of your primary brake levers, but they do add a small amount of complexity to your hydraulic lines.