The Suspension System
When reviewing the suspension system components and how they work together, remember that a bicycle in motion is more than wheels turning. As the tire revolves, the suspension system is in a dynamic state of balance, continuously compensating and adjusting for changing riding terrain and conditions. Today’s bicycle suspension system is engineering at its best.
The components of the suspension system perform these basic functions:
1. Maintain correct ride height and support bike and rider weight
2. Reduce the shocking effects of the terrain
3. Keep the tires in contact with the terrain
However, in order for this to happen, all the suspension components, both front and rear, must be in good working condition.
Main Components of the Suspension System
The main components of a bicycle suspension system are the Springs (air/coil), Damping System, Bushings and Stanchion Tubes.
Suspension is the compressible link between the rider and the ground. When an additional load is placed on a rider or, when the rider meets a bump in the trail, the springs in the suspension will absorb the load by compressing. The springs are a very important component of the suspension system that provides efficiency and ride comfort. The damping system helps control how fast the springs and suspension are allowed to move; this is important in keeping tires in firm contact with the trail.
During the vertical (up and down) movement of the suspension system, the upward suspension travel that compresses the spring is called compression. The downward travel of the wheel that extends the spring is called rebound. When the spring is compressed, it stores energy. Without the damping system the spring will extend and release this energy at an uncontrolled rate. The spring’s inertia causes it to bounce and overextend itself. Then it re-compresses, but will again travel too far. The spring continues to bounce at its natural frequency until all of the energy originally put into the spring is dissipated.
If the damping system is worn or blown and the bicycle meets a bump in the trail, the bicycle will bounce at the frequency of the spring until the energy of the bump is used up. This may allow the tires to lose contact with the terrain.
By controlling spring and suspension movement, the rider will have more traction and control when riding the trail.
Suspended and Un-Suspended weight; does this matter?
Suspended Weight is the weight supported by the springs. For example, the rider’s body, drivetrain, cockpit, frame, etc, would be suspended weight.
Un-Suspended Weight is the weight that is not carried by springs, such as the tires, wheels, and brake assemblies.
The springs allow the rider and frame to ride undisturbed while the suspension and tires follow the terrain. Reducing un-suspended weight will provide less terrain shock. A low un-suspended weight provides improved ride and also improves tire traction.
Inertia is the tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force.
What does this mean? The lighter you can make the Un-Suspended weight in your bike the easier it is for the suspension to start moving through the compression and rebound stroke, and once it starts going one way the lighter it is the easier it will be for it to change direction and start going through the rebound stroke. When you are bombing down a hill having less un-suspended weight will help your bike glide over roots, rocks, sluts and ruts.
Below is a simple suspension service. I am not going to explain a specific procedure, but I will show some little tips and tricks for when you do it yourself. Most manufacturers have the service instructions/procedures on their websites. Doing an oil change does not have to be hard. Take your time, clean and set up your workspace beforehand and always watch or read the tech vid/document.
After servicing suspension myself, I really started to understand why it’s important to change the oil frequently. Suspension oil breaks down over time with heating and cooling, plus your fork seals are never going to block 100% of the water or dirt from coming in. Suspension forks have tight tolerances with oil moving throughout the fork; if this oil is watery or dirty then you have watery dirt wearing all the components of your suspension prematurely. Below are a couple pictures from some fork services I have done.
I always believe bicycle maintenance should at least be tried by the bike owner. When you understand how things work it can help make your setup easier and your ride more enjoyable. Don’t be scared to attempt Suspension oil changes on your own. Remember to watch the tech video specific to your fork, make sure you have all the tools required and a clean work space. At the end of the day you can always take it to the Bikeroom, your local shop or SuspensionWerx.
This article is here to push you to check out the service/tech video on your suspension system, even if you are not going to try and tackle it on your own.
This article is brought to you by the Bikeroom, a Bicycle Mechanic Training Facility for everyone located right here on the North Shore. Visit us at www.bikeroom.ca
What kind of suspension user are you… a self-servicer, a take it to the shop regularly, or a forget it until it explodes kind of guy?