Chain cleaning tools only work when the brushes actually contact the chain. After enough degreasing sessions, those bristles wear down, pack with grime, and stop doing their job. The Park Tool RBS-25 is the replacement brush cartridge for the CM-25 chain scrubber, giving you fresh bristles without buying a whole new cleaning unit. When your chain starts coming out of the cleaner looking the same as it went in, worn brushes are usually the culprit.

The cartridge contains the complete brush assembly that slots into the CM-25 housing. Park Tool designed it as a user-replaceable component because brushes wear out long before the plastic housing does. The bristle arrangement matches the original equipment, with brushes positioned to scrub the chain from multiple angles as it passes through the cleaning chamber. You get the same cleaning action as a new CM-25 without the redundant parts.

Installation takes about thirty seconds. Pop the old cartridge out, drop the new one in, and you're back to cleaning chains. No tools required beyond your hands. Park Tool sells the cartridge separately because it makes more sense than tossing an entire cleaning unit when only the brushes are shot. The housing, handle, and reservoir on your CM-25 don't wear out from normal use—keeping them out of the landfill is the practical choice.... Read More