Often considered a ‘black-art’, tuning your suspension shouldn’t be a worry. We caught up with the experts of the castrol-backed Honda Gresini MotoGP team to find out how.
Adjusting your own suspension can be a daunting prospect. There are a seemingly infinite number of settings and combinations to be had, but customising your own ride to your style is hugely satisfying and can save you a packet. That’s why we produced this simple guide.First let’s find our rear and front static sag levels. It’s a baseline we have to get right before fiddling further.
First, lift the back wheel as far as it will go without the wheel coming off the floor. Measure the extension between two points – wheel spindle to a recognisable feature on the tail unit is best – and write this down. Now get a friend to hold the bike’s rear end while you bounce up and down on it. This returns the suspension to its resting position. Your bike should be lower than when it was ‘topped out’. Measure the difference between the two points and you have found your static sag measurement.
Again, lift the front to measure full extension between the wheel spindle and the bottom yoke, then bounce on the forks and let them return to their natural resting point before measuring again. You’re looking for a level between 20-30mm static sag at both the back and the front. If you’ve managed that, put a cable tie around your fork slider to see how much fork travel you’re using under braking. In an ideal world you want around 10-15mm left. Now that’s all done, let’s look at a few typical problems you may have with your bike and what you can adjust to help sort them. The best thing is to spend a day doing this. Make the adjustments, then go for a ride on the same route. Come back, write down what differences you felt and do it again. Try using the same day as you’ve then got identical road and weather conditions.
Solving common problems
Forks bottom out or ‘bounce’ or ‘chatter’ on the brakes: Add preload to give the forks more support. Have a look after a ride to see where that cable tie is. Is it near the bottom of the fork leg, past our ‘ideal’ 10-15mm left area? If so, you may want to add a little compression and reduce a little rebound. At best you’ll sort it, at worst you may need harder fork springs or thicker fork oil. The bike ‘tank-slaps’: Normally caused by the rear of the bike being too ‘soft’ and squatting under power. Add rear preload a turn at a time. Add a little compression too. If this doesn’t help, then back off the rear rebound. If it persists, you may need a stiffer rear spring. If the bike is old or has had a hard life, perhaps the shock needs servicing. The bike understeers or won’t hold a line through SuSpenSiona corner: The bike is too high at the front. Add more rebound or rear ride-height. If you don’t have ride-height adjustment, add more rear preload. Be careful though, as too much ride-height or preload can give you… A lack of rear end grip: Reduce preload by a turn, then back off compression damping a couple of clicks. Tank slapping, understeer and a loose rear end also suggest you may be riding too close to the limit. Always ride to the road conditions and speed limits to stay safe. Ultimately, setting up your bike is personal. Whether it’s static sag or rear rebound, it’s important to find what’s right for you.
Check your tyre pressures! More handling problems come from incorrect pressures than bad suspension set-up. If your bike feels fine then don’t adjust it. There’s no need! Don’t worry that changes will have a massively detrimental effect on your bike’s handling: Your average road bike isn’t as fickle or sensitive as a race bike, so even big changes won’t make your bike unrideable. Also, the suspension components are designed to work over a broader range of conditions: in wet or dry, one or two-up. If you want to adjust your suspension then don’t worry: You can always change the settings back to standard by consulting your owner’s manual. Write things down! Very important! Make a note of the settings you start with and any changes you make. Try and have a friend present to help you move the bike around.
Preload: This is the amount of tension set in a spring before a load (the rider or braking force) is applied. Without it your bike would sag under its own weight, too much and the springs barely move. Rebound damping: This controls how your springs ‘bounce-back’ or ‘rebound’ after being compressed. Without it your bike would bounce you out of the saddle over even the tiniest bumps. Compression damping: This controls the speed that the springs compress under load, for example: braking, accelerating and hitting bumps. Too much compression damping and the ride is harsh and unforgiving, too little and the bike will pogo from end to end.
Preload adjusters: these live at the top of the fork legs and normally require a 14 or 17mm spanner to adjust. Adjustments are made by turns and measured by the ‘rings’ marked on the exposed part of the adjuster. Rebound damping: Rebound adjusters are the flat-headed screw nipples on top of the fork. Adjustment is measured by turns, or half turns. Some will make an audible ‘click’ during adjustment so you can easily count them. Compression damping: Adjusted via a small screw in the base of each fork leg. Like rebound, count each half-turn while you’re adjusting. And remember to do each leg the same amount.
Preload adjuster: You’ll find a collar of some description on the rear shock. Some are at the bottom but most at the top of the shock. You’ll need the tool kit’s C-spanner for this. Double check your owner’s manual for the standard setting. Rebound damping: Again, this is normally a screw adjuster and it sits at the bottom of the shock making it pretty tricky to get to. Compression damping: Another small screw adjuster and it should sit on top of the shock or on the remote reservoir, if your shock has one. Ride-height: Some modern sports bikes may not have this. It’s a threaded nut adjuster either at the top or bottom of the shock that lifts the back end of the bike to help it steer quickly by placing more weight over the front-end. Many aftermarket shocks have this adjustment.