What Is the Shimano SM-BH59-JK-SS Brake Hose For?

The SM-BH59-JK-SS is Shimano's standard-pressure hydraulic disc brake hose, sold as a pre-cut 1700mm length with the JK-type straight olive and insert fitting on one end and an SS-type straight connector on the other. This hose is the correct replacement or build hose for Shimano hydraulic disc brake systems that use the BH59 specification, including a wide range of Deore, SLX, Alivio, and other mid-range Shimano hydraulic disc brakes. The 1700mm length is the longest standard cut available and accommodates full-suspension mountain bikes, larger frame sizes, and routing configurations with external hose guides where shorter hose lengths would fall short. The JK straight fitting connects directly to the brake lever body without a banjo bolt, while the SS end connects to the caliper port.

Installation requires cutting the hose to the appropriate length for the bike, inserting the olive and barb, and bleeding the system with Shimano mineral oil to remove air from the brake circuit. The SM-BH59 hose is designed for Shimano's mineral oil hydraulic systems and is not compatible with DOT fluid brake systems. It is not compatible with Shimano's higher-pressure BH90 specification brakes such as Dura-Ace or XTR, which require the SM-BH90 hose for correct operating pressure rating. For anyone building, replacing, or rerouting hydraulic brake lines on a Shimano BH59-spec hydraulic disc brake system, the 1700mm SM-BH59-JK-SS provides enough length to fit most frame configurations with material to spare for trimming.