A scratch or paint chip on a steel bike frame exposes bare metal, and after a few wet weeks rust appears. It creeps under the paint, the paint bubbles and a small nick becomes an orange patch. Aluminium frames do not rust in the same way but they oxidise and darken, while the steel bolts and fittings on them rust just as quickly.
The good news is that a scratch is easy to seal before corrosion starts. All it takes is regular cleaning, touch-up paint and a thin protective film.
What you will need
- bucket of warm water with mild detergent, sponge and brush
- clean dry cloths
- floor protection sheet
- fine abrasive paper and a degreaser (spirit)
- touch-up paint matching the frame
- WD-40 Multi-Use or WD-40 Smart Straw
Important: Keep lubricant away from brake pads, discs and rims used with rim brakes. Cover them with a cloth before treating the bike, and wipe any accidental overspray with spirit.
Step 1
Wash the bike after every muddy ride
Dirt, sand and road salt hold moisture right on the scratches. After a wet ride wash them off with warm water, mild detergent and a sponge, without aiming a strong jet at the bearings.
Dry the frame with a cloth and inspect it so you spot new chips in good time.
Step 2
Seal fresh scratches with a film
Until the scratch is painted, put a little WD-40 Multi-Use on a cloth and wipe the damaged area. The thin film drives moisture out of the metal and stops rust getting started.
Treat a chip with light surface rust the same way, leave it for a few minutes and wipe off the orange bloom.
Step 3
Store the bike somewhere dry
Only put the bike away when it is dry. The best places are indoors, a storeroom or a dry garage. On a balcony or under a shelter condensation forms in winter, and scratches rust even without rain.
If the bike lives in a hallway or cellar, renew the protective film on damaged spots more often.
Step 4
Touch up the scratches
The most reliable protection is to cover the metal with paint. Gently sand the chip back to clean metal with fine paper, degrease it with spirit and apply paint in thin coats, letting each one dry.
Important: there must be no lubricant on the surface before painting, so do not skip degreasing.
Step 5
Treat the bike after touching up
Once the paint is fully dry, go over steel bolts, fittings, chrome parts and metal areas where the lacquer has worn with WD-40 Smart Straw. The thin straw lets you place it precisely into gaps and threads.
Wipe off the excess so dust does not collect on the frame.
Tip: Most scratches appear where the frame touches a lock, a car rack clamp or a parking stand. Stick clear frame protection film on these spots and treat the metal underneath with lubricant.
What next
In season check the frame every two weeks, and in autumn and winter after every ride on salted roads. A pocket WD-40 100 ml fits in a backpack for quick treatment of fresh chips.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».