Suspension 101: Things You Need to Know

A modern motocross bike is equipped with front and rear suspension. Your suspension consists of your forks in the front and a shock in the rear. Suspension consists of two key components, springs and dampening. You can see the spring on your rear shock. The springs on the front of your bike are in the fork tubes. Dampening is controlled with oil that is pushed through internal components called valves and is adjusted with small screws called clickers. These are the small screwdriver driven mechanics you see on the top of your fork tubes. They also exist on the bottom of your forks and on your rear shock. Refer to your manual if you are unable to locate your clickers. Now that we have a basic understanding of what suspension is, let’s talk about how it works and go into some details on the components.
 

Springs

The springs in your bike are non adjustable, they are simply pieces of metal wound into a spring. A spring is built to hold a certain weight. These are called spring rates. In order for your bike to work properly you must start with the proper spring rate. No amount of clicker adjusting can compensate for the incorrect spring rate. Spring rates are measured in kg/mm. If your spring rate is too soft you will be compressing your suspension to much just by sitting on the bike. If your spring rate is too hard, you can’t compress the suspension enough. Most modern motocross bikes are sprung from the factory for a 170 lb rider. Lighter riders need springs with a lighter rate and heavier riders need springs with a higher rate. As a general rule faster riders like their equipment a little stiffer, but don’t assume because you are a faster rider you need heavier springs. You just need to adjust your clickers which we will talk about later. Remember springs are static, they are non adjustable. You get the right spring rate for your weight and then go from there.

Dampening

There are two types of dampening, Compression Dampening and Rebound dampening. Compression and Rebound work together to control how your suspension moves through its stroke. Compression Dampening is what controls how the suspension compresses. Oil is forced through adjustable valves. Valves control the amount of oil flow and thus control the speed at which the suspension can travel through the stroke. With your bike on the ground, press down on your seat or on your handlebars while standing next to your bike. This downward motion is controlled by your compression dampening. If your compression is too soft your bike will bottom out. If it is too stiff the bike will feel harsh. Your rear shock has both high speed and low speed compression dampening which we will cover in more detail later. Rebound Dampening controls how fast the suspension returns after it has been compressed. The rebounding motion your bike makes after you have pressed down on the seat or the handlebars is controlled by rebound dampening. If the rebound is too fast, your bike will have a tendency to kick. If it’s too soft you will have the feeling of packing because the suspension doesn’t have enough time to return to it starting position before hitting the next bump on the track.

Sag

What is sag? Sag is used to describe the amount of distance your suspension will travel (sag) under weight. If you take your bike off the stand you will notice the suspension compresses (sags) slightly.

There are two kinds of sag. Rider/Race sag and Free sag. Free sag is the distance the rear end travels while under its own weight, whilst rider sage is the distance the rear end travels under the weight of a rider in full gear. Sag is important because it balances out the front and the rear of the bike. Before you begin messing with clickers, it is important to set the sag of your bike. Too much sag means the bike sits high in the front. This affects the front ends ability to absorb bumps and can make the back of the bike feel harsh. You may also notice the front end will tend to push in corners. Too little sag means the bike is sitting high in the rear and the bike will tend to kick and it can feel like your shock rebound is too fast, which can be misleading when you are adjusting your shock rebound. Although there is not a hard number for Rider/Race sag the general consensus among professionals is that it should be in the 96-108mm range. Your free sag should be in the 20-45mm range. Free sag should always be measured AFTER your rider/race sag has been set.

There are 5 adjustments (clickers) on modern motocross suspension, Fork Compression, Fork Rebound, Shock low speed compression, Shock high speed compression, and Shock rebound. Each of these is responsible for making suspension working properly. They each control a piece of suspension, but all work together to make suspension work as a single unit.

Fork Compression

Your fork compression is used to control how much your forks travel when hitting bumps. The goal is to use all of your fork travel without bottoming out. It is ok for your forks to occasionally bottom out. If you feel the forks bottom once in a while chances are your compression is adjusted pretty well.

 

Fork Rebound

Fork Rebound is how fast your front wheel returns to the ground after being compressed. Properly adjusted fork rebound will improve straight line handling as well as how your bike works in corners.

 

Shock low speed compression

This is where things get interesting. Low speed and high speed compression do NOT refer to the speed at which the bike is traveling. It refers to how fast the shock is traveling. Low speed compression is used to adjust how the suspension works at low shaft speeds or using a short amount of stroke. Examples would be: rolling sand whoops, braking bumps or steep jump faces.

 

Shock high speed compression

As before, low speed and high speed compression do NOT refer to the speed at which the bike is traveling. It refers to how fast the shock is traveling. High speed compression is used to adjust how the suspension works at high shaft speeds or using its full extension. Examples would be: curbed out jump faces, square edged bumps, supercross style whoops, or hard landings.

 

Shock rebound

Shock rebound controls how fast your shock returns your rear wheel to it starting position. Properly adjusted shock rebound will prevent your rear end from kicking up or packing when hitting bumps. It will also help soften landings without bouncing.

We hope your able to use some of this information while out on your next ride. Remember Twistin’ Grips and Bustin’ Lips. Braaap

  • Yamahammer

    Nice information. I should be able to put this to use this weekend. Thanks.