Forks / front suspension

How it works

The fork is the motorcycle's front suspension: two tubes (the sliders and the stanchions) that slide into each other and contain a spring and an oil damping system. The spring carries the weight of the bike and rider; the oil, flowing through calibrated holes, slows the movement so the bike doesn't bounce. There are conventional forks and upside-down forks (stanchions at the bottom), which are stiffer. Oil seals at the top of the sliders keep the oil in and, with the dust seals, wipe dirt off. Over time fork oil degrades and damping becomes soft; a worn seal or a stanchion pitted by rust or stones lets oil escape, and it can run down onto the disc. Many forks allow preload, rebound and sometimes compression adjustment. A well-maintained fork directly affects handling and braking.

Maintenance tips

• ✓Wipe the fork tubes regularly and check there is no oil film above the dust seals.
• ✓Fix a fork oil leak quickly: the oil can reach the front disc and pads.
• ✓Change fork oil at the interval in your manual, with the specified viscosity and level.
• ✓Check the tubes for rust pits or scratches: they destroy new seals.
• ✓Suspension affects handling: if in doubt (bent fork, odd behaviour), have a professional check it.