An innovative piston retractor for bicycle hydraulic disc braking systems

Abstract

Hydraulic disc brake systems offer various advantages over other braking systems, including a good heat dissipation rate, a high force enlargement ratio and a constant braking force in various environments. However, they have an important defect as the lining pads remain at a small clearance from the disc rotor, occasionally producing judder, noise and power loss when freely running. This study proposes an innovative piston retractor by utilizing the theory of innovative problem solving. The prototype is manufactured and installed in a commercial brake caliper. Experimental results are obtained and demonstrate the feasibility of applying the proposed design in a bicycle hydraulic disc braking system. Retraction performance of the proposed design is superior to a current product with a ring seal as its retractor and another product with a retractor that does not contain an automatic adjustment mechanism. The clearance between the lining pad and disc rotor is successfully kept at a larger value than these products regardless of the pad wear.