Abstract: The wear resistance of rubber O ring roller chains and ordinary roller chains for motor cycle was comparatively investigated by road test and simulated bench test. The worn surfaces of the chains were observed as well. It was found that the rubber O ring roller chains showed better wear resistance and longer antiwear life than the ordinary roller chains. The bushes and bearing pins of the rubber O ring roller chains were characterized by stress fatigue wear and adhesion wear; while the chain plate and rubber O rings by stress fatigue wear. The bushes and bearing pins of the ordinary roller chains were characterized by abrasive wear, together with stress fatigue wear. A cyclic surface hardening occurred for the bushes/bearing pair and chain plate/rubber O ring pair in the road test and bench test, which contributed to improve the wear resistance of the pairs.