Every hydraulic brake hose has two small components that quietly hold the whole system together, and when one fails you're rebuilding the connection from scratch. Shimano's BH-59 Brake Hose Olive and Insert set covers both pieces for a single hose end—the brass olive that compresses against the lever or caliper body to create the seal, and the barb insert that supports the hose from the inside so it doesn't collapse when the fitting torques down. If you're shortening a hose during a fresh build, replacing a leaky connection, or routing a new line through an internally cabled frame, these are the parts you burn through.

The olive is designed to deform permanently as the compression nut tightens. That deformation is what makes the seal, which also means you cannot reuse an olive once you've broken the connection. Pull a hose off a lever for any reason and you need a new olive before you put it back together. The barb insert presses into the cut end of the hose and gives the olive something solid to compress against, preventing the hose wall from crushing under fitting pressure.

This is the second-generation fitting (Y8H298040) that covers Shimano's BH59, BH62, BH63, and BH96 hose lines. It works with both standard lever connections and J-kit configurations, which Shimano uses on many factory-installed OEM brake systems. Compatible levers include ST-RS685 and ST-R785 road hydraulic units along with the mountain and gravel calipers that share the BH59-family hose interface. Note that this fitting is not interchangeable with the BH90-series hose used on higher-end Shimano brakes—those require a different olive and insert.... Read More