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Spring Time Motorcycling

No, we ‘ere at CB-NET aren’t quite out of synch with the seasons (although the British weather always is) instead, here are the basics of your bike’s suspension system explained…

If you ever want to fiddle with your suspension, the very first thing is to check your tyre pressures and make sure they’re spot-on as if these are out, any issues you have with the bike may be down to that. Then ask yourself if you actually want to change things anyways: if the bike feels good to you, then don’t touch it. What would be the point?

If you want to change things, then here’s a simple guide to the adjustment available to you and what they do. The best rule is to set up your static sag first and then make one adjustment at a time, ride the bike and see what difference it makes.

Another rule: always make a note of the standard settings, so you can easily go back to them….

Static sag:  This is the free play in your suspension between maximum extension and a normal resting position at a standstill. Lift the back of the bike as far as it will go without the rear wheel leaving the ground and measure between the wheel spindle and a mark on top of the tail unit. Then allow the bike to return to its normal position and measure it again. The difference is basically your static sag. Ideally you want between 20-25mm. Repeat this process with the forks to find your front sag. Remember, more preload means more sag and vice versa.

Preload: This is an amount of tension set in a spring before a load is applied. It’s the most basic suspension adjustment found on motorcycles: you’ll often find budget bikes only have this sort of adjustment. Generally, the (ahem) heavier you are, the more preload you’ll need to dial in.

Rebound damping: This is what controls the speed of your spring’s rebound or ‘bounce back’ after being compressed. Without it, the bike would bounce you out of the saddle over bumps, while too much rebound and your springs won’t have time to recover between the bumps and the bike will squat down, so a happy medium is required!

Compression damping: This controls the speed at which the springs compress under load – that means during braking, accelerating and hitting bumps. Too much and it will feel harsh, too little and your bike will see-saw from one end to the other.

Where are the adjusters?

At the front

Most bikes have a pair of forks at the front. The preload adjusters sit at the top of the legs and generally require a 14mm or 17mm spanner. Adjustment is by turns and measured by rings marked on the exposed part of the adjuster. The more preload you wind in, the fewer rings are left showing. Make sure you adjust them together so the settings are the same: and as we remarked earlier, either consult your manual for standard settings or make a note of what settings you started with.  

Front rebound adjusters will be on the top of your fork legs – they’re the flat-headed screw nipples that poke out of the preload adjusters. These are measured by turns and many will make an audible click when you turn them. Compression damping is adjusted via screw heads like rebound, but the adjusters themselves are found at the base of the forks, near the front wheel spindle.

At the back…

Preload is put on at the back via a collar normally on top of the spring on your shock absorber. Sometimes the preload collar is at the base of the shock so do check this! Adjustments are made with a C-spanner. Compression damping can be altered by a flat-head screw adjuster at the top of the shock body, while the rebound adjuster can be found at the base of the shock: this normally has another screw-type adjuster.

Some machines will even have a ride height adjuster which will be a threaded adjuster with a locking nut at the top or bottom of the rear shock. To do the same at the front you’ll need to move the forks through the yokes themselves. Many bikes don’t have this adjustment available, unless an aftermarket shock is fitted.

Ride height is the height between the ground and the bike’s steering head and subframe: changing ride height between front and back alters the bike’s trail. Basically less height at the front makes the bike steer quicker, but will make it less stable. More height at the front lengthens trail and makes the bike more stable, but at the expense of quick steering.