A carbon frame is light and stiff, but it has one important trait: unlike aluminium or steel, it does not bend before it breaks. Damaged fibres can look intact and then crack suddenly under load.
So caring for a carbon bike comes down to two things: regular inspection and gentle cleaning. Take extra care after a crash, after carrying the bike on a rack and after winter rides on salted roads.
What you will need
Important: If after a crash the frame, bars, steerer or seatpost show cracks, bulges, ripples or discolouration, or you hear cracking while riding, stop riding and have the bike checked at a workshop. Keep all care products off brake discs, pads and rim braking surfaces.
Step 1
Inspect the frame and carbon parts
In good light, check the frame, fork, handlebar and seatpost. Cracks, scratches down to the fibre, bubbles and darkened lacquer can indicate damage. Tap a suspicious spot with a fingernail: a duller sound than the area next to it is another warning sign.
A bar, stem or frame badly damaged in a crash should be replaced; if in doubt, let a bike shop specialist decide.
Step 2
Wash the bike gently
First rinse off sand and salt with clean water and no pressure, then clean the frame with a soft sponge and a neutral shampoo solution. Abrasive compounds, scouring powders and pressure washers are off limits for carbon.
Clean the chain and sprockets separately so dirty drivetrain lubricant is not spread across the frame. Dry the frame with microfibre after washing.
Step 3
Deal with minor lacquer scratches
Shallow scratches that only affect the lacquer can be carefully flatted with fine wet-and-dry paper and covered with clear lacquer. Never sand into the fibres. Blasting, chemical paint stripping and powder coating are unsuitable for carbon.
Step 4
Leave serious damage to specialists
Repairing fibres with carbon cloth and resin takes skill, and a mistake costs safety. Hand deep frame damage to a specialist workshop, which will judge whether repair is worthwhile.
Step 5
Protect the frame and lubricate the mechanisms
Apply WD-40 Specialist Silicone to the clean, dry frame: spray it onto a cloth, spread it and buff. The film adds shine and repels water and dirt, making the next wash easier.
Treat metal bolts, cables and derailleur springs precisely through the WD-40 Smart Straw, and lubricate the chain with WD-40 Bike Chain Lube. Do not use ordinary lubricants on carbon interfaces such as the seatpost in the frame or the bar in the stem: they need dedicated carbon assembly paste, and bolts should be tightened with a torque wrench to the value marked on the part.
Tip: Carry a carbon bike on a rack that holds it by the wheels rather than clamping a frame tube. A clamp designed for steel can crush thin carbon walls.
What next
Inspect the frame after every crash and once a month during the season, and repeat the protective treatment after each wash. In the off-season, WD-40 Multi-Use will protect the bike's metal parts from rust.
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».