Brake for bicycle

The utility model discloses a brake device for a bicycle, which is composed of a brake control part, a power separation part, and a brake part. The utility model separates a part of energy from the inertial force which requires to brake in a brake, and consequently, the external force for checking braking can be replaced. Therefore, the utility model has the advantages of the brake effect is improved; the labor for braking is saved; the brake efficiency is improved; the requirement of checking braking is met; the reliability is enhanced; the purposes of saving and high efficiency are achieved; a bicycle can thoroughly solve the problems that the effect of braking is poor and bicycle rims are worn; the reliability of braking is enhanced.