Front disk brake for a bicycle

A front disk brake assembly comprising a brake disk fixedly mounted on a hub at a front fork of a bicycle, and a brake caliper mounted on the front fork of the bicycle and pulled by a brake line to actuate said brake disk, said brake caliper comprising a mounting frame fixedly mounted on the front fork of the bicycle, a body mounted on said mounting frame, two cam shafts mounted in said body, and a pull bar driven by the brake line to turn said cam shafts for enabling said cam shafts to be moved toward two opposite side walls of said brake disk, wherein:

• said mounting frame is a substantially U-shaped member having two first screw holes and two second screw holes, said two first screw holes being configured to receive lugs for fastening said U-shaped member to the front fork of the bicycle,
• said body includes a narrow slot for receiving said brake disk, two receiving chambers at two opposite sides of said narrow slot, an inside annular groove respectively provided inside each of said receiving chambers, a plurality of steel balls respectively received within a plurality of semispherical receivers formed within said inside annular groove of each said receiving chamber, an axle hole extending through said receiving chambers and said narrow slot, two first screw holes provided at two opposite sides of said body through which respective mounting screws are fastened to said two second screw holes of said U-shaped member, two second screw holes disposed at two opposite sides of said body and respectively peripherally intersecting said two first screw holes of said body and two positioning screw bolts respectively threaded into said second screw holes of said body for retaining the mounting screws in place;
• and,
• said cam shafts are respectively mounted in the receiving chambers inside said body, each said cam shaft comprising a flat, circular head having a top side wall and a bottom side wall, a shaft body perpendicularly extended from the center of the bottom side wall of said circular head, a plurality of ball grooves formed at the bottom side wall of said circular head around said shaft body, said plurality of ball grooves receiving the steel balls within the inside annular grooves in said body, said shaft body having a square retaining end fastened to a respective square hole at one end of said pull bar, and said ball grooves each having a depth which gradually increases from a narrow end thereof toward a broad end thereof.