A bicycle disc brake caliper is provided with a cooling system that transfers heat away from the actuating fluid. Basically, the bicycle disc brake caliper has a housing and a piston unit, with a coolant member of the cooling system attached to the housing. The housing has a frame mounting member sized to be coupled to a portion of a bicycle frame. The piston unit is movably coupled to the housing between a release position, in which the piston unit is spaced from a brake disc mounted to a wheel of a bicycle, and a braking position, in which the piston unit engages the brake disc of the bicycle wheel. The coolant member has a coolant area for receiving coolant to create a coolant heat sink that transfers heat from the housing. The housing has an actuating passage in fluid communication with the piston unit to move the piston unit via an actuating fluid. In one embodiment, the cooling system includes a pump and a reservoir. In another embodiment, a coolant or water bottle is a attached to the coolant member for manually adding coolant thereto. In another embodiment, the coolant member is filled with a high specific heat gel.