A bicycle hydraulic brake actuation device includes a hydraulic master
cylinder housing having a bore and a push rod guide surface, a master
piston and a radial seal received in the bore, a push rod and a lever.
The push rod is supported by the push rod guide surface for sliding
movement within the hydraulic master cylinder housing. The push rod is
configured to move the master piston and the radial seal from a neutral
position to a braking position. The lever is pivotally attached to the
housing for pivotal movement between an at rest position and a brake
actuation position. The lever is also configured and arranged to move the
push rod and the master piston from the neutral position toward the
braking position as the lever is pivoted between the at rest position and
the brake actuation position.