Track craft: Tweaking your motorcycle suspension
Finding the perfect setting comes from seat of the pants feel, rider feedback and trying out with new adjustments, but no sooner have you found it and improved your lap time, you’ll need to find it all over again at another circuit or under different riding conditions. If your own suspension settings are way out, the bike can be very difficult to control and your tyres could be destroyed after just a few sessions, so if it doesn’t feel right, ask for advice. It’ll save you cash in the long run!
Basic suspension changes
If you’re adventurous and confident, basic suspension changes can be made through adjusting your spring preload, ride height and the compression and rebound damping – these are easy to tweak and you should be able to feel the difference between just a few clicks or turns. There’s a lot more available to adjust, but for trackday riders this should be enough.
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Just to give you an idea of how many different settings you could have, imagine starting out with approximately 0-30 clicks of compression, 0-30 clicks of rebound, 0-10 turns of preload and a full range of different spring strengths for both the front forks and the rear shock absorber. That’s without choosing different oil thickness, shim-stacks, top-out springs, high and low speed compression adjusters or geometry changes.
You should really write down all of your suspension settings and keep a record as you adjust them, especially if you have aftermarket suspension or you’re looking to improve lap times and progress into racing. Once your front and rear static sag has been set, you should always start at the manufacturer’s recommended base setting with compression and rebound and from there you will adjust to suit.
What is sag?
Sag is the amount of travel through the suspension without having a rider or additional force going through the suspension, so as it sits with both wheels on the ground and just the weight of the bike forcing the springs to compress. Front sag should be around 25mm-28mm and the rear sag should be 5mm-15mm and this is measured by bouncing on the suspension and allowing to settle, taking a measurement from two fixed points and then completely extending the suspension until topped out and retaking the same measurement – the difference between the two measurements is your sag and it applies to front and rear ends.
Sag is changed by adjusting the pre-load on the springs – you reduce the amount of sag by adding more preload. Once you’re within the parameters and you have the default compression and rebound settings, then you have a base starting point. But what if it still isn’t quite right?
Dean’s suspension guide
Rear, ripping up on the edge: Rebound damping is slow and this normally happens when you have a long corner with hard drive on to a straight and the rear end squats without returning quick enough.
Lack of rear grip: Rear end is too hard or too high – start with taking off some preload and a little bit of compression. If this doesn’t improve grip, go back to the original setting and then lower the rear ride height.
Tank Slapper: More than likely this is caused by the rear end being too soft, so try adding some preload and even some compression damping a click at a time. You can also try lifting the rear ride height.
Front forks bottom out under braking: This is obvious – your front fork setting is too soft, but don’t just keep winding more preload on. If you like the way your front end feels, but you are bottoming out into hard braking areas, then you should probably be adding some more fork oil to keep from hitting the stops. It they’re diving, you should add a little bit of compression damping as well.
Bike understeers: Your front end is high, so try taking some of the preload off and adding some rebound damping. You can also lift the rear end or just add some rear preload to the shock spring.
Know more about sprockets here