Suspension setup explained
Motorcycle Suspension Setup Explained
Author: My friend from FastBikeFinder, Simon aka 'sinic'
See also: The Motorbike Suspension Bible (external link)
Another good read: www.gostar-racing.com/information/motorcycle_suspension_set-up.htm
|AndyW - usual warning, refer to manufacturers workshop manual.|
Having the suspension on your bike set-up as best it can be for the type of riding you do is the most important modification anybody can make if they intend on getting the most from their bike. The best part of this modification is that it doesn't cost a penny.
A bike that has the suspension set-up correctly will improve the handling of the bike by raising the confidence the rider has in the machine, increases traction and grip levels and will ensure you minimise the risk of over-stepping the line which marks the limit when riding fast. Tyre wear will also be minimised and kept constant, and thus last longer. A tyre that shows much distress on the surface is often due a less than optimal suspension setup.
This simple guide will introduce the basic concepts of suspension setup and allow you take what you're experiencing and build a plan for getting a better setup. This guide was compiled with the experience of Simon from fastbikefinder.com and Senior Instructor for Focused Events.
Front Suspension Setup
· Need a socket to fit the top of the forks.
· Sag needed, approx 25-30mm (with rider on board) to be equally adjusted on both forks
More preload helps prevent the forks from `bottoming out` under severe braking. You can check this by putting a cable tie around the fork leg, near the seal to see how much suspension travel is used when braking on the limit. Ideally you`ll still want about 10mm left of travel if possible. If you`re bottoming out or almost have no travel left then dial in a bit of preload (about one full turn at a time to start with).
It also pushes more weight on to the rear of the bike, which gives better traction. Overdo it and the bike will not turn as well and as quickly, as there's less weight on the front tyre. Too much preload on the front will also cause a harsh ride and make the tyre work harder as it doing more of the suspensions` work now.
Reducing the preload gives more sag at the front end and puts more weight over the front tyre. You will achieve more feel from the front when turning into corners, especially after braking. Go too far and the forks will travel too much under braking and may bottom out again.
· Need a flat blade screw-driver
· Adjusted at top of forks, equal adjustments to be made on each fork.
Rebound damping damping controls the speed at which the the forks return to their original position after being compressed. If there is not enough rebound damping then the forks will `pogo` and bounce around. Giving you the feeling of little control and no feel. It also unloads the front tyre too quickly which could cause loss of front end traction. It can also cause the bike to run wide in corners and harder to hold a line through bends.
So dial in a half a turn at a time and then perhaps a 1/4 or 1/8 turn either way to fine tune. Try it out, you`ll be amazed at the difference these adjustments can make. These adjustments are much more than recommended, but we suggest these as you`re more likely to notice the difference and you can then fine tune afterwards. Most bikes we've seen have been lacking in rebound damping front and rear.
· Need a flat blade screw-driver
· Adjustment on bottom of forks, equal adjustments to be made on each fork.
Compression damping controls the rate at which the forks compress. Again, generally we find road bikes are too soft here as well.
Wind it up a bit and your bike will dive less under braking and work much better on smooth roads and track days with much more feel from the front tyre. Too much compression will firm up ride and turn a bike from a smooth ride into a boneshaker. Over do it completely and the forks wont compress quickly enough causing instability especially over bumpy roads. This also makes the tyre work harder, causing more wear as it`s doing more of the suspensions work than it should be.
Back the compression damping off and the bike will cope with bumps better and use more of its travel to make things smoother. Turn it off too much and the front will dive too quickly under braking and placing too much weight transfer to the front tyre too quickly, potentially overloading to the point of losing traction of the front tyre.
Rear Suspension Setup
· C-Spanner from OEM toolkit.
· Adjustment near top of the shock.
Normally adjusted with a C-Spanner. Sag is the amount of suspension travel your bike takes up just supporting its weight or can also be measured with the rider on it. It should be about 20-25mm loaded (with rider & gear) at the rear for the road and less for the track. Increase the preload and the bike will sag less.
More preload will raise the rear ride height which will make your bike steer quicker and change direction faster. But too much will make it unstable.
Sag measurements are a very general guide for most road bikes and are debateable, but if you`re in the range you should not be far off. We prefer to set the sag with the rider on the bike as this will tailor the sag for you individually.
When carrying extra weight ie: a pillion, you`ll also need a bit more rear preload as well as more front preload, so giving you more usable suspension travel again and reducing the chance of `bottoming out` the suspension.
· Need a flat bade scew-driver
· Adjustment found at bottom of rear shock normally
Again an area where we've noticed most road bikes need a bit more. When adjusting, again start with 1/2 turns at a time to get a feel for it and then fine tune again. Standard settings are generally about 1 1/2 to 1 3/4 from the fully screwed in position so yes 1/2 turns at a time is a lot, but it will be easier to see how certain adjustments effect the bikes handling. It really is down to practice and getting a feel for it.
It's probably too soft also, if like the front rebound, it is bouncy and pogo`s a bit much. `wallowing` is also another indication that the rebound damping may need increasing.
· Need a flat blade screw-driver
· Adjustment found towards top of shock.
This controls the rate at which the shock is compressed. Wind it up too much and you'll be bouncing out of the seat over bumps and more likely to get a rear end slide coming out of the corners on the power as the rear is reluctant to grip efficiently as it should be squating more to get the weight over the rear.
Too much rear compression will put the tyre under too much stress as you put the power down. Get it spot-on and the bike will track straight and hold a tighter line and be able to get the power down more easily as the rear needs to squat a little to get a bit of weight transferred to the back.
Back the rear compression off too much and the rear of the bike will squat down too much, causing understeer (running wide). It will also cause the front tyre to go light. The result is that you will run wide in corners.
Wind it off too much and the bike may bottom out over bumpy roads and wallow around under pressure.
Suspension Adjustments - Conclusion
When making adjustments to your suspension, always work on one aspect at a time, i.e. the rebound, compression or damping, always make notes of what you do so you have a reference should you want to change things back again in the future, and remember that there's no perfect suspension setup possible, it's always a compromise, depending on where you're riding.
Also, before you make any changes to your suspension, ensure your tyre pressures are set at the correct level for the type of riding you are doing, as the pressure of the tyres is critically important to the handling of your bike. This small fact should not be overlooked. Worn tyres will also adversely affect the handling and this should be addressed before trying to evaluate the suspension settings.
If you make changes to your suspension settings, why not discuss it in the forums to let others know how you get on? Someone might learn from your adjustments and experiences. Please also remember to take it easy when test-riding your bike after making a change, and to work the pace up progressively so you become acustomed to the changes, rather than being surprised mid-corner when it doesn't behave as you expect.
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