Bicycle brake device

A bicycle brake device to be installed on a bicycle frame which has a bicycle wheel mounted rotatably thereto, comprising:

• a curved brake arm formed with an elongated slot therethrough and adapted to be mounted pivotally on said bicycle frame;
• a metal annular retaining seat confining a hollow space therein and having a front end which is formed with a pair of diametrically opposite retaining notches, a rear end which is formed with an annular inward flange, and a knurled rear end surface;
• a metal annular support seat confining a hollow space therein and having a knurled front end surface, a rear end which is formed with an annular inward flange and a rear uneven friction face which abuts against one side of said brake arm;
• a spring unit which is disposed in said hollow space of said support seat and which has two ends that abut respectively against said flange of said support seat and said flange of said retaining seat;
• a washer provided with an uneven friction face that abuts against an opposite side of said brake arm;
• a bolt having a spherical head and a threaded shank, said spherical head being formed with a diametrical through hole that is transverse to said threaded shank, said threaded shank extending through said retaining seat, said spring unit, said support seat, said elongated slot of said brake arm and said washer, a portion of said spherical head extending into said hollow space of said retaining seat;
• a nut engaging a distal end of said threaded shank and being rotated relative to said threaded shank so as to retain said spring unit in a compressed state and permit said knurled end surfaces of said retaining seat and said support seat to engage one another;
• and
• a brake block having a front face which is provided with a brake pad and a rear face which is provided with a shaft projection that extends through said through hole of said bolt and that engages said retaining notches of said retaining seat, said brake arm being pivoted so as to move said brake block to contact said bicycle wheel in order to brake said bicycle wheel.