Advice: Suspension setup part 1 – components

One of the most common subjects across the motorcycling sphere is suspension. As with anything to do with riding motorcycles, there are usually simple explanations for everything that happens, making it a matter of just taking the time to analyse each individual action and the resulting consequence.

In this forum we’ll just concentrate on ‘standard’ suspension, leaving an in-depth analysis of electronic suspension to another discussion.

Simply put, the suspension’s job is to keep the wheels on the ground – giving you a nice comfortable ride is very much a secondary consideration! This means that how the suspension works will directly affect arguably the most important concern when riding a motorcycle: traction.

The way you ride can affect the suspension’s operation. If you are holding on too tightly and putting too much input into the bike, you are not allowing the suspension to complete its task. traction is then compromised, and the bike will tend to run wide. It will also amplify any bumps or deviations in road surface by transferring the force back and forth between your body and the bike.

No amount of changes to the bike will overcome the problems associated with the rider doing something to the motorcycle which interferes with the way the suspension is supposed to work. So, riding problems aside, how does it all work?

There are several components to the suspension system of any motorcycle. Each one has a specific role and design parameters, as well being effected by adjustments to the other components. There are two major operations of any set of forks or shock absorber. They are:

• Springing
• Damping

The spring has two variables: preload and spring rate. Preload is adjusted by changing the fitted length of the spring thereby changing the amount of initial force needed to begin movement of the spring. Changing the preload also affects a very important part of the basic setup which is 'static sag' (we'll talk a little more about that in the next issue).

The spring rate on the other hand can only be adjusted by changing the spring. It determines the amount of force needed to keep the spring moving, which can be lesser or greater depending on the amount of coils and the thickness of material used for the spring.

The damping's job is simply to control the spring’s speed of movement. There are two basic parts: compression damping, which deals with the rate at which the forks or shock can compress or dive, and rebound damping, which deals with the rate at which the suspension can extend or raise.

Without damping to control the spring, it would be free to continue moving the force backwards and forwards along its available travel, which would be substantially more than you want on a motorcycle. (If you have ever jumped up and down on a pogo stick, you'll know what a spring feels like without any damping!)

So, this means you have four totally different ways in which to change your suspension. When you consider that most modern sports bikes have multiple damping and preload adjustments, along with a plethora of different rate replacement springs available, you now have literally thousands of possible combinations. Add to this the fact that the front needs to be balanced with the rear, and it's no wonder most riders are confused about what to do with the suspension.

Over the next few articles we'll break down basic bike set-up and give you at least a starting point for you and your motorcycle.