Anti-lock brake system for a bicycle

An anti-lock brake system for a bicycle having sliding assembly (30) (having a brake shoe (40) therein) and a plurality of springs (50) defined in a brake shoe holder (20) in turn, a bottom of the brake shoe holder (20) and a connecting side of the sliding assembly (30) are correspondingly in gradient formed and both of them to be abutted against each other and they are slanted formed outwardly in accordance with the direction of the rotation of the tire of the bicycle. The sliding assembly (30) further includes a plurality of recesses (21) formed therein for receiving sliding members (80), an abrasion-resistant member (90) disposed at the bottom of the recess (21) of the brake shoe holder (20).