Hydraulic brake hoses eventually need replacement. Frame swaps, crash damage, contaminated fluid, or simply refreshing an aging system all require new hose, and the SM-BH90-JK-SSR from Shimano provides everything needed to connect a lever to a caliper in one kit. The 1700mm length works for most bikes on either the front or rear brake, with enough extra material to trim for shorter routing paths. You'll cut it down for front brake use on most frames.

The hose itself uses braided polyester construction that resists expansion under pressure. When you squeeze the lever, you want that force transmitted to the caliper without the hose ballooning and absorbing energy. Firmer hose means more direct lever feel and more consistent braking response across temperature changes and repeated hard stops. The system runs Shimano mineral oil, which is safer to handle than DOT fluid and won't damage paint or carbon if you spill during installation or bleeding. Shimano's One-Way bleeding process works with this hose for straightforward maintenance.

Each kit includes the hose plus all necessary fittings: olives, connecting inserts, and hardware for both the lever and caliper ends. The JK-SSR designation indicates straight connections at both ends, which matches the flat mount road calipers in the Dura-Ace, Ultegra, 105, and GRX lines. Compatible levers include the current 12-speed Di2 models (ST-R9270, ST-R8170, ST-R7170, ST-RX825) as well as 11-speed hydraulic levers like the ST-R9170, ST-R8070, and the mechanical-shift ST-R7020. You need one kit per brake, so order two if you're setting up a complete bike or replacing both hoses during a frame transfer.