Chain cleaning machines work great until the brushes wear out, and then you're just sloshing dirty solvent around without actually scrubbing anything. The Park Tool RBS-5 gives you a complete set of replacement brushes for the CM-5 and CM-5.2 chain cleaners, so you can restore the scrubbing action instead of replacing the whole unit. The kit includes all four brush assemblies that make contact with your chain—the components that actually do the cleaning work.

Inside the box you get two sponge assemblies and two brush assemblies, which covers every wear item in the cleaning chamber. The sponges handle the initial wipe-down and help contain the solvent, while the stiff-bristled brushes dig into the chain's side plates, rollers, and inner link surfaces where grime accumulates. When these components wear down, the cleaner loses its effectiveness regardless of how fresh your solvent is or how vigorously you backpedal.

Installation takes about a minute with no tools required. The brush assemblies snap into the same mounting points as the originals, and the sponges press into their channels. Park Tool designed the CM-5 series with serviceability in mind, which is why they sell these kits separately rather than forcing you to buy a new cleaner every couple of years. If you're maintaining multiple bikes or running a chain cleaner through heavy use, keeping a spare RBS-5 on hand means you're never stuck with a worn-out unit when your drivetrain needs attention.... Read More