WP Suspension Technology: Your best link to the road!
Motorcyclists travel under an extremely wide variety of conditions. Busy city traffic, country lanes with potholes, motorways and slippery mountain roads with hairpin bends.
In every situation you should be able to place blind faith in your shock absorbers, which in fact form the link between you and the road. The road holding of your motorcycle determines your safety. With this in mind, it's vital that the factors which control the road-holding are in good order. This is true not only for the speed-kings on the circuit, but also for relaxed tourers.
In this section we want to explain to you the basics of motorcycle suspension and some of the effects it can have. Reading this information contained is well worthwhile, especially if you wish to equip your machine with high quality components and are interested in increasing your comfort and safety on the road.
Basics of Suspension
If the shock absorbers and front forks function optimally, you will hardly notice the effects from the surface you are driving over. The mass of your motorcycle moves forward in a constant line, while the wheels and shock absorbers soak up the 'jolts and bumps'.
That absorption of the 'jolts' is achieved by the spring and the damper that are incorporated into the shock absorbers. The spring, but especially the damper, repress the jolts and bumps from the surface. The outgoing force from the spring is also absorbed by the same damper. The positive result of this is that you do not roll and pitch, or even worse, leave the road surface. Briefly, in other words: The most important function of the spring is to bear the weight of the motorcycle and prevent the shock absorber from being fully compressed. The spring also helps ensure that the motorcycle is always returned to its original position. The damper represses all in and outgoing movements and contributes to stability. With a well functioning shock absorber and front forks you are able to ride with stability, comfort and safety.
Poorly functioning shock absorbers are always dangerous and inhibit optimum comfort.
What are the effects of poorly functioning front forks and/or shock absorber?
- Bouncing and rolling of the motorcycle after riding over a bump or pothole.
- Shocks through the suspension after riding over a bump or pothole.
- Continuous heavy steering required to keep the motorcycle in one line.
- Steering difficult in bends and tyre 'wandering'.
- Front forks pull towards the straight line and the rear suspension swings (unstable
motorcycle).
Now you can read how to perform a test to help you determine the cause of dangerous conditions as described above. A cause requires a solution, so solutions have been included too. Even if the above conditions cannot be clearly established, but you nevertheless have a feeling that the 'handling' of you machine could be improved, you can still perform the same tests. The results of the test will enable you to determine if the performance of your shock absorber and front forks can be improved.
Test your bike’s suspension performance yourself
Three first test routines are described below which can all be performed on a stationary motorcycle. Go through the three steps one after the other. It is always useful if someone is there to help you, by holding the motorcycle upright, while you carry out the examination.
1. Pull in the front brake and apply your full weight onto the front suspension, release your weight at the lowest point.
Ideally, the motorcycle will spring rapidly back into the upright position. The front forks should be adjusted so that motorcycle springs back evenly and stop at once. The machine should not bounce, neither should it shoot up roughly or rise back up very slowly.
2. Force down the rear of the motorcycle into the spring(s) as far as you can, releasing it at the lowest point. The motorcycle should rise back up with a smooth and flowing motion (controlled by the shock absorber). Too rapid spring back is undesirable, so is bouncing or a very slow spring reaction (too much rebound damping).
3. Sit on the motorcycle in your normal riding position. This will apply normal static load to the springs. The motorcycle should move evenly on the springs at both the front and the rear. If this is not the case the adjustment between front and rear is not in balance.
If your motorcycle shows normal behaviour in the above tests your suspension and damping seem to be in order, but 'standard'. If you don't think standard is good enough and would like the suspension effects of your shock absorber and front forks to meet your 'personal' preferences, we suggest you perform a more extensive road test (see next). You may have a personal preference with respect to the comfort and characteristics of your motorcycle. The ideal suspension for yourself can be realised if you take the weight with which your motorcycle will be loaded into account (solo and/or with pillion passenger or luggage). If you wish to ride comfortably and safely, the suspension should be adjusted to the circumstances under which you usually ride for long periods of time. Using the results of the road test you can determine which components require adjustment and how they can best be adjusted.
The road test is especially recommended if, following the three stationary tests, you have established that the suspension is functioning properly. You can also try to solve the problems encountered by readjusting your shock absorbers and front forks. If readjustment does not provide the required result you can make use of the trouble shooting section mentioned further.
The solutions can also be applied in case you have a shock absorber and front forks that do not function correctly, and which you cannot adjust because no adjustment options are available.
Some important notes to performing a road test:
- Always use the same test route.
- First, set all adjustments to the standard factory settings (only applicable if these adjustments have been changed).
- Naturally, you must always wear a helmet and protective clothing.
- Wear the same clothing, sit in the same position and drive at the same speed.
- Drive with extra caution. Driving a road test requires double concentration. You not only have to pay attention to traffic, but also to the behaviour of your machine.
- Test critically. A modern sport motorcycle often has so many adjustment possibilities, that an inexperienced mechanic will have difficulty in making the correct adjustments. In any case, first try the standard settings recommended by the manufacturer.
- When making adjustments, always only adjust one setting at a time.
- Always record any adjustments you make, and the effects they have. You don’t need to be afraid of getting confused. After all, you can always return the motorcycle to the standard factory settings when you take notes.)
A few technical terms explained
Before you actually start your test rides, it is worthwhile knowing a little shock-absorber jargon. To start with, spring pre-load. This setting influences the height at which your motorcycle will ride. The higher the spring pre-load, the higher the riding height of the motorcycle. The spring pre-load can be adjusted by turning the spring collar/spring retainers, which may also be fitted with a locking ring. When you place the motorcycle on its wheels, the front fork will settle, by several centimetres, under the weight (sprung mass) of the bike. This is known as the "negative spring distance", "sag" or "neutral riding position". This negative spring distance (without rider) should be somewhere between 15% and 35% of the total spring distance (fork or shock stroke). Example: the total spring distance is 120 mm. The negative spring distance therefore should be between 20 and 40 mm. This can be easily measured by winding a cable tie around the shock-absorber spindle(s). With rider, the spring distance should be between 35% and 50%. Example: the total spring distance is 70 mm, so the negative spring distance should vary between 25 and 35 mm.
Compression absorption occurs when a shock-absorber or front fork is compressed, while rebound or bump absorption describes the opposite effect.
From diagnosis to therapy
To help you rapidly find the source of your problems (and then solve them) what follows is a brief total overview of several different suspension problems.
TROUBLE SHOOTING OVERVIEW
REAR SUSPENSION
Complaint
- too little negative suspension travel
- motorcycle shocks through the steering in ruts or when accelerating
- shock absorber appears immobile
- uncomfortable
- overloading on front forks when travelling downhill or braking
Cause
- spring pre load too high
Solution
- reduce spring pre load
- fit a softer spring if necessary
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Complaint
- motorcycle dips too deeply on suspension
- too much negative suspension travel (“sag”)
- uncomfortable
- tendency to shocking
- motorcycle wanders on uneven surfaces
Cause
- spring pre load too low
Solution
- increase spring pre load
- fit a harder spring (or springs)
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Complaint
- very uncomfortable
- rear wheel tends to bounce in fast bends especially when accelerating
- rear wheel bounces over uneven surfaces
Cause
- compression camping too hard
Solution
- adjust damping to softer level
- have the shock absorber adjusted internally
- have worn shock absorbers repaired or replaced
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Complaint
- Rear suspension bottoms out
- motorcycle and rider subject to hard bumps
- Noticeable movements in the frame, particularly when accelerating out of bends
Cause
- compression damping too soft
Solution
- set compression damping harder
- have the shock absorber adjusted internally
- have worn shock absorbers repaired or replaced
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Complaint
- motorcycle suspension extremely sluggish
- rear wheel unable to cope well with uneven surfaces
- tendency to bounce on bumpy surfaces
uncomfortable - tendency to snake in ruts
Cause
- rebound damping too hard
Solution
- decrease the rebound damping
- possibly increase spring pre-load
- replace shock absorber
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Complaint
- motorcycle suspension extremely lively
- constant movement in the rear suspension
- rear wheel has tendency to bounce / wobble
Cause
- rebound damping (rebound) too soft
Solution
- increase the rebound damping
- reduce the spring pretension if necessary
- have worn shock absorbers repaired or replaced
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FRONT SUSPENSION
Complaint
- front forks sluggish/nearly immobile
- handlebars “jump” in your hand when accelerating and crossing ruts
- uncomfortable
- front wheel bounces / chatters on poor road surfaces
Cause
- spring pre load too high
- spring too hard
- air chamber too small
Solution
- reduce spring pre load
- fit softer springs or progressive springs with a lighter initial strength
- increase air chamber (reduce oil level in front fork)
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Complaint
- motorcycle sags to deeply on the springs
- too much negative suspension travel
- suspension occasionally bottoms out
- front forks shake when braking and travelling downhill
Cause
- spring pre load too low
- springs too soft
- air chamber too large
Solution
- increase spring pre load
- fit stiffer springs or progressive front fork springs with a heavier initial strength
- reduce air chamber (increase oil level in front fork)
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Complaint
- front forks sluggish/nearly immobile
- shocks in the steering when accelerating
- front wheel chatters when braking hard
Cause
- ingoing (compression) damping too hard
Solution
- reduce the ingoing (compression) damping
- possibly use lower viscosity fork oil
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Complaint
- front forks shock when braking and on uneven road surfaces
and dips rapidly when braking
Cause
- ingoing (compression) damping too soft
Solution
- increase the ingoing (compression) damping
- possibly use higher viscosity fork oil
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Complaint
- front forks spring back slowly
- uncomfortable
- front wheel unable to cope with uneven surfaces
- indirect steering behaviour
Cause
- outgoing (rebound) damping too hard
Solution
- reduce the outgoing (rebound) damping
- possibly use a lower viscosity fork oil
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Complaint
- front end is lively
- bouncing and shocking on uneven surfaces
- front forks spring back too quickly
Cause
- outgoing (rebound) damping too soft
Solution
- increase the outgoing (rebound) damping
- possibly use a higher viscosity fork oil
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Complaint
- front forks shock
- front wheel shudders
- not enough progressive hardening of the spring towards the end of travel
Cause
- air chamber too large
Solution
- increase the oil level in small steps of 5 to 10 mm
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Complaint
- forks hard
- tendency to shock in the steering
- front wheel bounces when braking due to hydraulic stop blocking
- uncomfortable
Cause
- air chamber too small
Solution
- decrease the oil level in small steps of 5 to 10 mm
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Your step to extra safety and comfort
You have completed your test drive. In the most favourable case, thanks to the adjustments you have made to the shock absorbers and front forks you will have been able to achieve good results. If after making your test drive and adjustments you are still not satisfied with the result there are usually three main reasons for this:
1. Your shock absorbers and front forks are of poor quality.
2. The components in your shock absorbers and front forks are worn.
3. Your shock absorbers and front forks cannot be correctly adjusted.
A fundamental solution for your problem could lie in simply replacing your shock absorbers and front forks with a set of shock absorbers and front forks (or front fork springs) of superior quality, with adjustment options that enable you to adjust them fully to your personal preferences.
WP Suspension have complete shock absorbers for every motorcycle. If you already own WP shock absorbers and front forks, you have all the advantages of a maintenance friendly product, for which it is not always necessary to replace complete shock absorbers. As a result of the components in the shock absorber being replaceable you can solve your problem for less cost.
An extra advantage of WP shock absorbers is that less burden is placed on the environment as result of their long durability.
For front forks from other manufacturers you can use the excellent replacement springs manufactured by WP. We will be able to explain to you in detail which components have to be replaced in order to solve your problem.
By choosing the quality and the customising options of WP products, you are choosing for optimum safety and comfort.
Now get down to work!
You have now completed your test ride, and you have taken exact note of your motorcycle's behaviour. Now you can get down to work dealing with the problems. As long as you understand that adjusting the suspension and shock-absorption is very precise work. If, when it comes to the settings, you are not one hundred percent sure about your capacities, leave the job to the professionals, but with this document as a guide, you should in principle be able to achieve the optimum settings, (that is if adjustments are possible at all, because with certain types of shock-absorbers, there could be no adjustment possibilities, whilst on some other motorcycles, only the pre-load and rear suspension can be adjusted).
Let us assume now that you have readjusted your shock absorbers and, on your test ride, the results are still not acceptable. What can you do then ...? Possibly your existing suspension elements are worn out or are simply of poor quality.
Sometimes, replacing the suspension elements is the only possible solution. This may be extremely far-reaching, for example, completely replacing the front forks with new forks of a superior quality, but fortunately, spectacular results can also be achieved for a much lesser expense. An excellent alternative, for example, is to fit WP ProLine front fork replacement springs. Contact us about this most economic option. If the rear shock absorber (or both rear shock absorbers is (or are) working poorly, the only possible solution is to fit (a) new unit(s). If you are not by nature a “do-it-your-self” kind of person, we would recommend leaving this task to a specialist.
Made-to-measure work;
In replacing the shock-absorbers for WP units, you can express your own preferences. WP shock absorbers are of a particularly high quality and, just as important, WP Suspension has a complete range of suitable units for every model of motorcycle. It is exactly that which is vital, to guarantee optimum safety and comfort. The best suspension and shock absorption can only be achieved by using suspension components made specifically for your motorcycle. In other words, made-to-measure work.
New suspension elements: a new motorcycle!
The road-holding of your motorcycle will undergo a total metamorphosis, if you fit the correct new suspension units. The steering characteristics will be much more responsive and comfort will be drastically improved. Besides safety, you will also greatly increase the pleasure of riding your motorcycle, and when it comes down to it, that is what it is all about. New suspension elements can turn your motorcycle into a completely new machine. Definitely reason enough for you to take a critical test ride.