The wisest investment you can make to modifying  your motorcycle will be to the suspension. You can have all the power, accessories and graphics kits on the market, but they will not help you go your fastest until your suspension is properly adjusted and tuned for your style and ability. There are many variables on your forks and shock that can be adjusted... raised, lowered, increased and decreased... which will affect your landings, braking, acceleration, turning and straight line stability.  Each one of these adjustments can and does affect another one, so it is necessary to have all variables properly adjusted and the components clean and in good working condition to balance and optimize your suspension performance. Below is an outline of the fork and shock adjustments that you should be familiar with. Following that will be a summary on the best approach to getting the right combination. Print this out and read it over. By knowing exactly what you have, you can help us, at Shock Therapy, provide you with exactly what you need in the way of high performance custom suspension.

EXTERNAL SUSPENSION ADJUSTMENTS DEFINED

Compression Damping: Compression is the action of your suspension as it moves from fully extended towards a collapsed or compressed position. Your suspension compresses when you land from a jump, when you hammer through a section of whoops on a track or trail and during hard acceleration. The compression damping adjustment for most rear shocks is usually a knob or screw near the reservoir at the top of the shock. The compression damping adjustment for most forks is usually at the bottom of the fork leg. Turning clockwise will increase the compression damping making it harder. Turning counter clockwise will decrease the compression damping making it softer. Compression adjustments affect the first two-thirds of travel while the last third is adjusted with internal valving.

Some suspensions are not consistent with these top and bottom locations and clockwise vs. counter clockwise directions. Also, in addition to normal compression damping most later model shocks have separate high and low speed compression adjustments. Always check your owners manual and be sure you are familiar with the adjustments locations and operation.

Rebound Damping: Rebound is the action of your suspension as it returns to its fully extended position after being compressed fully or partially. Your suspension will rebound as you launch off a jump, after you land and in between acceleration or braking bumps and whoops. The rebound damping adjustment for most rear shocks is usually a screw near the bottom of the shock where it attaches to the linkage. The rebound adjustments for most forks is usually a screw at the top on the fork caps. Some suspensions are not consistent with these usual locations so, always check your owners manual and be sure you know where the adjustments are located.

Preload: Preload, sometimes called race sag, reflects the difference between the suspension when it is fully extended and when it is compressed with the rider on the bike in riding position.  Correct spring preload depends on rider weight and will adjust the ride height of the motorcycle front and rear, thus affecting cornering and straight line stability. Preload is adjusted using locking adjusting rings near the top of the shock. Measuring preload is accomplished by taking a measurement from the axle up to a seat bolt or a mark on the rear fender, when the bike is on a stand with wheels off the ground, then taking the same measurement with the rider in full gear in riding position with the bike on flat ground. The difference between the two measurements is the preload setting.  Fork preload can be set using spacers internally on top of the fork springs under the fork caps but it is best to set preload on the shock and compliment it with fork adjustments like tube height and spring rate.

Sag: The definition of sag, sometimes called static sag, is the difference between the suspension when it is fully extended and when the bike is on flat ground under its own weight, measured in the same manner as described above. Sag measurement is the result of setting preload, so take this measurement after the preload is adjusted. The benefit of checking sag it that it can tell you if your springs are too stiff or too soft. Sag on a shock should be approximately one inch. Less than half an inch means it takes too much preload on too soft a spring. More than an inch and a half means the spring is too stiff.

Spring Rate: The springs can be replaced with stiffer or softer springs, measured in lbs per inch or kg per millimeter. Candidates for bikes that need different springs are those who's riders are approximately 20 pounds lighter or heavier than what the manufacturer anticipates. For 250cc bikes and up average weight is 150 to 160 lbs. For 125cc bikes it's 130 to 140 lbs and for 80cc bikes it would be 90 to 100 lbs. Other factors should be kept in mind however, such as sag measurement, riding style and the bikes response to other external adjustments. Proper springs can also improve cornering ability if adjusting the fork height and shock preload hasn't helped enough. Stiffer springs can also help the suspension ride higher in the more supple first few inches of travel and help alleviate frequent bottoming.

It is easy to get confused when fine tuning your suspension, but keep notes of all your results and ask a professional tuner for advice.

SUSPENSION ADJUSTMENT BASICS

Before starting you should be sure all your swing arm and linkage bearings and bushings are clean, well greased with a good waterproof grease and in good working condition. Since dry and worn bearings can cause inconsistent results each time you ride, it will be impossible to to get accurate readings while making suspension adjustments.

Adjust preload by following the preload outline above and make adjustments to ride height to optimize your cornering and and straight line stability.

Adjust shock compression by finding the best compromise between hard landings and rough straights. Use the high speed adjustment to prevent bottoming on landings and high speed hits. Use the slow speed adjustment to smooth out rough straights.

Adjust shock rebound to give a plush feel entering and exiting corners without kicking. It is important to balance this adjustment with the forks to keep a level take off on jumps.

Adjust fork compression to complement the shock. Too soft compression will give a sluggish feeling in turns and cause bottoming on landings and ramps. Too stiff will cause bumps and edges to be transferred to your hands and arms and your bike will have a tendency to stand up in corners.

Adjust fork rebound to provide a smooth compression stroke. Too much rebound damping (or too soft springs) will cause straight instability and head shake. Too little rebound damping will make the steering feel twitchy and cause the front end to rise over jumps.

Adjust fork height one or two millimeters at a time to even the front and rear ride height and to maximize or find a balance with cornering characteristics and straight line stability

To get a good feel for the function of each adjustment and what can be gained or lost, first try an experiment; try turning an adjustment all the way out, go for a slow ride then turn the adjustment all the way in and take another slow ride. You'll realize characteristics that will inhibit or even be dangerous at fast or racing speeds. For instance, if you turn the compression knob all the way in you'll feel what too much damping is like and all the way you will feel what not enough is like. Turn the rebound all the way in to find out that your suspension will not spring back quickly and compression packing will occur. Turn it all the way out and your back end will not want to stay in touch with the ground and may even buck you off when landing from a jump. Start at one extreme and gradually work toward a comfortable setting. Go through the six adjustments above in order. Get it in the ball park on the first go around then start from step one again and fine tune everything. This may take half a day but once you are dialed in you can keep notes and make changes for different tracks and different conditions quickly without confusion.

Enjoy your ride,
Seve Piattoni