Degreasing a chain while it's still on the bike creates a mess that ends up everywhere except where you want it. Park Tool's CB-4 Bio ChainBrite solves this by working inside their chain cleaning devices, where the solution stays contained and the rotating brushes do the actual scrubbing. The formula uses a bio-based solvent system that cuts through road grime, chain lube buildup, and the black paste that accumulates on drivetrains without the harsh fumes of petroleum-based degreasers.

The 16-ounce bottle provides enough solution for multiple cleaning sessions depending on how dirty your drivetrain gets between washes. CB-4 works with Park Tool's CM-5.3 Cyclone chain scrubber and the CM-25 professional cleaner, filling the reservoir where chains pass through the brush mechanism. The bio-based formula rinses clean with water, so you're not leaving residue that interferes with fresh chain lube application. It's also safer on skin contact than traditional degreasers, which matters when you're inevitably reaching into the cleaning device to reposition a stubborn chain.

For shop use or home mechanics who clean chains regularly, keeping a dedicated bottle of CB-4 on hand means the chain scrubber is always ready to go. The solution works on all chain types including those with factory wax coatings, though heavy wax buildup may require a soak rather than a single pass through the scrubber. Park Tool designed this specifically for drivetrain cleaning rather than as an all-purpose degreaser, so the formula balances cutting power with material compatibility for the plastics and seals in their cleaning devices.... Read More