Short answer
Yes, WD-40 can be used to help clean a bike chain, but it works as a cleaner or degreaser, not as a lasting lubricant. If you use it, follow up with a proper bike chain lube and wipe off the excess. A product made for bike drivetrains is often a better fit than the standard multi-use spray.
WD-40 as a cleaner vs a lubricant
The standard multi-use spray is a light solvent and water displacer. That makes it reasonable for loosening dirt and old grime. It is not generally regarded as a good long-term lubricant for the chain’s pins and rollers, and it can wash away lube that was already there. So think of it as step one, and chain lube as step two.
WD-40 also sells a bike-specific line, including a chain cleaner and degreaser. Those are formulated for drivetrains, and the can’s directions apply.
Cleaning with WD-40 on a rag
This approach limits how much solvent gets into the chain.
- Put the bike on a stand, or otherwise keep the rear wheel off the ground.
- Spray WD-40 onto a clean rag, not directly onto the chain.
- Hold the rag around the chain and turn the cranks backward slowly so the chain runs through it.
- Move to a clean section of the rag as it gets dirty and repeat until the chain looks clean.
- Wipe the chain dry.
Using a bike-specific degreaser
If the chain is very dirty, a drivetrain degreaser is usually the better tool.
- Place cardboard or a rag under the drivetrain to catch drips.
- Apply the degreaser while turning the cranks backward.
- Let it sit for the time the label suggests.
- Scrub with a brush, including the cassette and derailleur pulleys if they are dirty.
- Rinse or wipe off as directed, then let everything dry fully.
Keep it off the brakes
Spray solvents can contaminate brake pads, rims, and especially disc rotors, which can hurt braking (see what to check when disc brakes will not stop the bike). Shield the wheel or rotor with a rag or cardboard before spraying, and keep spray away from the brakes. If you suspect contamination, check the brakes before riding; squeaky brakes are one common sign.
Re-lube afterward
Once the chain is clean and dry, apply a bike chain lube to the rollers, turn the cranks a few times, and wipe off the excess. How often to repeat this is covered in how often to lube a bike chain.
Can you use WD-40 instead of bike grease or lube?
It is generally not recommended as a replacement for chain lube. It may quiet a dry chain briefly, but it is not designed to stay in place and protect the chain under load and in wet conditions.
What about a rusty chain?
Penetrating oils such as WD-40 are sometimes used to loosen lightly rusted, stiff links, followed by wiping and proper lubrication. Heavily rusted chains are a different matter; see whether a rusty bike chain can be saved.