Quick access even when riding upper body The underwired auxiliary brakes may have a strong image on an entry-class road bike, but this product is extremely rare as an auxiliary brake, and is dedicated to hydraulic disc brakes. When it comes to auxiliary brakes, we think that most people have an image on an entry class road bike. The auxiliary brakes on the entry class road bikes are primarily to allow beginners to brake even on flat handles. The longer rides on the road bike may be an already rimless part. However, for gravel bikes that are growing in recent years, auxiliary brakes that provide a greater advantage beyond beginners with an off-road descent. Of course, it is also an advantage that you can safely remove the upright position during long rides such as touring. The auxiliary brakes are not just for beginners. Besides that beginner, the auxiliary brake lever is also recommended for use with hydraulic disc brakes by SHIMANO GRX. Do you feel like you can run on any road with the GRX Compo, including the 650B thick tires and the BL-RX812 supplementary brake? Or it is very attractive to use on long ride bikes at 700C. Why not make your own bike with the BL-RX812 and GRX Compo? For installation, the handle clamp diameter: 1.2 inches (31.8 mm) and the pipe should be straight about 1.6 inches (41 mm) from the edge of the BL-RX812 clamp to the support point surface. The Shimano GRX BL-RX812 Inline Brake Lever provides superior cyclist control for mixed terrain riding with Shimano technologically leading hydraulic disc brakes. Hydraulic disc subbrake lever provides reliable, maneuverable braking in more positions. Quick brake access from top handle position Allows for more secure braking from various positions to reduce fatigue on long rides