Shimano zee m640 disc brakenew zee hydraulic disc brake systems are gravity rated with a servo wave brake lever and new 4 piston ceramic disc brake caliper system stiffness is tuned using shimanos high power hose and shorter lever blade while ergonomics are perfected with a new pivot location and dimpled surface ice tech brake pad and rotor options reduce heat in the system and maintain performance on the longest descents with their consistent feel and trouble free performance shimanos brak