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Modern suspensions comprise of a spring, oil and a cartridge system to control damping. They offer a host of adjustments such as spring preload which can be accomplished both manually by turning an adjuster ring directly on the spring or hydraulically controlled. They can have compression and rebound damping adjustments and adjustments to the length of a rear shock and let’s not forget that more and more shocks are now offering both a high speed and low speed damping adjustment. Add in different spring rates, oil heights and oil viscosity (weight) along with riders of different sizes and abilities and you have a receipt for potential disaster in the hands of the unknowledgeable. This will be a multi part article to help you wade through your suspension, help you understand how it works and walk you through on how to set up your bike’s suspension. Once initially setup you’ll need to spend time playing and tinkering with your suspension to help you understand how it works in real world applications. I do that by finding a stretch of road with variables in road surfaces and terrain that I know like the back of my hand. Using a note pad and taking copious notes while spending several hours going back n forth on this stretch of road will lead you to the ideal settings for you and your bike and hopefully understanding suspension well enough to know if you need a change of spring rate, oil height adjustment and/or the help of a professional suspension tuner.

While I do not consider myself an expert, I believe I have a pretty good understanding of suspension and how it works. I’ve spent more than my share of time running around the race track and in the early days often off the track trying to figure out what happened. More often then not it was purely rider error but the faster I got the more I realized that suspension was one of the key’s to going around quickly while keeping both tires in proper contact. Most of my knowledge is by trial and error and collecting every tidbit of info that I could find. Most often I’ve found that so called experienced riders were more often misinformed or misunderstood suspension. Fast guys at your local tracks understand suspension. Maybe not in the technical manner but they can express what they are experiencing to a suspension tuner who then make changes to the suspension for irregular handling problems. Most cannot or do not wish to relay their knowledge to the uninformed as there are just too many variables and often results in frustration for both. Unfortunately, suspension is not a one size fits all. What works for one most likely will not work for another. In order for a suspension professional to help you, you must first understand the basic’s so that you can speak the same language. I hope that this will be a step in the right direction for you and your enjoyment of performance motorcycle riding.

On the surface suspension seems pretty basic. Its primary job is to keep the tire in contact with the road surface. A motorcycle without suspension moves over a rough surface, the whole motorcycle must rise and fall over every bump. The faster the motorcycle moves, the more rapid this up and down movement becomes. Bumps hit at high speed can kick the motorcycle up pretty hard, but it can’t return any faster than gravity will allow. The faster you go the more control you need with this up and down movement. Without it, your tire will end up spending more time in the air rather then on the road surface where you most need it.

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Placing a spring between the tire and motorcycle is the first step in suspension. The problem is controlling the spring after it was compressed. The spring will apply equal pressure but now in the opposite direction. What you end up with is an undamped oscillator and you’ll quickly find yourself bobbing up and down as you travel down the road. Likewise, in sudden maneuvers undamped suspension will cause the bike to wallow and dive. You need something to isolate this unwanted movement and help rid the spring of its pent up energy. This is where damping comes in and no it’s not called “dampening”. Dampening is the act of wetting a rag…nothing to do with suspension :).

Damping on a modern motorcycle suspension uses a system known as a cartridge system. Most have a separate circuit for the compression stroke and the rebound stroke. Company’s like Ohlins and Showa use a cartridge that consists of a piston that has a ring of holes through it. These holes are covered by a stacked set of shims that will vary in both size and width. As the suspension moves up and down oil is forced through the holes, deflecting the shims into a slight cone shape. The faster the piston moves, the more the shim stack deflects, increasing the amount of oil flowing past. By stacking the shims with the largest first, against the piston, then adding gradually smaller shims or shims of various thickness and/or spacers the oil can easily move the edges of the first shim(s). As the pressure increases the larger shims bend further coming into contact with the smaller shims giving more resistance or damping. This is exactly what you want; damping that is proportional to velocity. At low speeds suspension is fluid and moves easily. As speeds increase, damping increases by bleeding off the energy in the spring and maintaining tire to road contact. The second most common type is that by Kayaba and Works Performance. Rather than using shims they cover hole(s) in the valve piston with a ball backed by a spring. By choosing the rate and preload of these tiny springs, the ball valves can be made to open in proportion to oil forces, producing the right curve of damping versus piston velocity.

Previous to modern cartridge systems motorcycles used damping rods which had a fixed orifice drilled at specific points of the rod. With this system you could adjust the placement and size of the orifice to work pretty well at a specific rate of travel. The downside is this system is set and not adjustable. A damper system based on this system is useless because it becomes rigid in response to sharp quick movements in the suspension. Remember damping is exponential to rate of velocity. You could set it up for a race track but forget about low speed plushness. Set it up for the average street rider and you won’t like how it reacts at racetrack speeds or quick movements of suspension like hitting a pot hole. It was a one size fits all and a compromise overall. Damping rod systems have a damping curve that curves upwardly at an alarming rate in response to velocity. Unfortunately many riders are still under the belief or assumption that “harder is better”. This is nonsense as any good tuner can adjust a cartridge system to work well in most any situation if given the right input. A good suspension is set to give predictable motion control at low speeds, preventing wallowing. As the piston moves faster in response to higher suspension movements the washer stack begin to open up or deflect to allow more oil flow and take control of damping, thus giving good control during almost all but the most extreme of conditions.

A suspension tuner adjusts this stack of shims to not only the spring rate but also to the rider’s preferences and abilities and remember that spring stiffness and damping force must exist in proportion. Too much damping overcomes the spring, slowing suspension response, making the ride too firm and reducing the wheels ability to maintain contact and grip. Too little damping is overcome by the spring, and the motorcycle oscillates, or wallows after every disturbances. Rider A who weights 185lbs and can turn 2:10 laps at a local track may find his suspension perfect. Rider B, on the same motorcycle, who also weights 185lbs but can turn 2:05 may find that the suspension does some funny things that result in a lack of confidence in his suspension. Add or subtract a little damping and rider B’s suspension may dial right in. Take rider C who is 220lbs and runs 2:12 is told he needs heavier springs. Once installed, rider C still lacks confidence in the suspension. Unfortunately the damping is unable to hold the motorcycle in a stable manner. It now has to correctly absorb not only the additional weight of the rider but the increased energy of the suspension. Manufactures set up suspensions to fit under conditions the bike was designed to operate in, this includes riders size and ability. While cartridge systems offer adjustability unmatched in previous systems there are limits of adjustability and quality.

So what is the clicker for? Most suspensions have adjustment for both compression and rebound. This clicker serves to adjust low speed motion control, and acts as a trimmer or fine-adjustment on higher speed damping. Think of it as an adjuster that can slightly raise or lower the whole damping curve. This adjuster CANNOT change the shape of the curve. If the curve is wrong or the problem lays outside the clicker’s range of adjustability then only a suspension tuner can help. Some shocks are now coming with high speed and low speed damping adjustments. As it sound, this allows fine adjustment to each circuit. What is low speed? What is high speed? Low speed would be when you press down on the suspension. When pressing down you’re feeling the tension of the spring and compression damping. When released the bike moves upward. The rate of movement is governed by the rebound damping circuit in relation to the energy being expelled by the spring. High speed would be when you hit a pothole at speed or in many cases dips or sharp rises in the road surface. A motorcycle moving along at 25mph and hits a dip it may be classified as a low speed movement but raise the motorcycles speed and its now a high speed damping movement. Just remember that the clickers will only vary the damping slightly.

Another thing to realize is that the quality and adjustable range can vary greatly by manufacture. Take a GSXR750 which has 4 turns of adjustability. From a closed position (fully clockwise) to 1 turn out there is quite of bit adjustment of damping. However, to get the same amount of adjustment you would need to turn the adjuster from 1 turn to 3 turns out. The rate of this adjustment is variable on many manufactures suspension systems. Moving just ¼ turn between closed and 1 turn out may be all that’s needed whereas a turn from 2 ½ to 3 ½ may be required. Ohlins on the other hand may offer 25+ clicks of adjustment and in most cases one click to another offers similar adjustment to damping throughout the clickers range. Tuners will often replace pistons to make the clicker more effective or offer a more linear range of motion.

So how does the clicker work? Typically the compression clicker presses an aluminum rod that has a hole drilled through it. This rod goes through an oil passage that bypasses the piston. Turning in reduces the amount of oil passing through the hole thus making it more resistant to movement. Rebound typically moves a long aluminum rod in and out of an orifice on the piston, again, controlling the amount of oil passing through. Neither effect the shim stack itself nor its function of controlling damping.

Part 2 will be along shortly. I will discuss springs types, oil and oil height and bike attitude. Part 3 will be about setting preload. A step by step how to. Understanding how to know if you need a stiffer or softer spring. Then on to setting damping. I’ll also include a list of suspension terminology, discuss de-carbon style shocks versus emulsion and list cause and effects of damping.