A caliper brake of bicycle includes a yoke at one end of a second arm, the yoke comprising two yoke arms having a hole, and a spring depressible detent at one end; and a mechanism comprising a manipulation member disposed between the yoke arms and comprising a C-shaped element including outer teeth and an inner protrusion, and a handle; a brake cable retaining member; a cylinder secured to the brake cable retaining member and comprising outer recesses and an eccentric tunnel. The protrusion is engaged with one recess. The cylindrical member is fitted in the tunnel. The detent is urged against one tooth. A brake cable is held tight. In response to counterclockwise rotating the handle the tunnel moves upward and both the detent moves to another tooth and the protrusion moves to another recess so as to loosen the brake cable.