The invention provides a bike operating device, and the device comprises a base component, a hydraulic cylinder, a piston and a fluid passage. The base component is arranged on a bike. The hydralic cylinder is arranged on the base component and comprises a cylinder bore. The piston is movably arranged in the cylinder bore. The cylinder bore and the piston limit a hydraulic cavity. The fluid passage is connected with the hydraulic cavity. The fluid passage is arranged in the base component. The fluid passage is longger than the length of stroke of the piston.