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Glossary

Coil Spring
Air Spring
Travel
Bottom Out
Top Out
Sag
Dynamic Sag
Preload
Lockout
Damping
Compression Damping
Rebound Damping
Low Speed Damping
High Speed Damping
Linear Rate
Progressive Rate
Falling Rate
Spiking
Nitrogen Charging

 

 

Coil Spring – probably the most common form of spring, it’s a coil of wire, steel or titanium, where different thickness's and lengths and sizes of coils are used to make them harder or softer. It is important to have the correct spring for your weight, bike/shock/fork and riding style so that your suspension can work as it should and for your bike to handle as it should.

 

Air Spring – instead of using coil spring, air can be compressed to create a spring. The more the pressure, the harder the spring. . It is important to have the correct pressure for your weight, bike/shock/fork and riding style so that your suspension can work as it should and for your bike to handle as it should.

 

Travel – this is the amount the wheel can move from the suspension being fully extended to fully compressed.

 

Bottom Out - this is the term used to describe when the suspension is fully compressed and cannot move any further. It can feel harsh and can damage your suspension if it happens too frequently, if your suspension is set up correctly, it should only bottom out occasionally.

 

Top Out – this is the term used to describe when the suspension is fully extended and it comes to a harsh stop. This is not good for your suspension and will be a fault with set up or a sign that your suspension needs servicing!

 

Sag – this is the measurement of how much of the suspensions travel you use up when stationary on the bike in your normal riding position. This needs to be adjusted correctly for good set up. It can be done by changing springs, preload and air pressures.

 

Dynamic Sag – this is the measurement of how much of the suspensions travel is used most when you are actually riding the bike. From this measurement it is possible to see how the bike’s angles are positioned when you are actually riding it. This is only measurable by using Data Acquisition equipment like J-TECH’s Data Logger.

 

Preload – this is the amount of force the spring is under before you can compress it. You adjust the preload on a coil spring to set up your sag.

 

Lockout – this is common on xc bikes, it is a control that allows you to lock the suspension, to stop it moving. You would use this for road or fireroad sections so that you are not moving the suspension when pedalling. There are mechanical and hydraulic lockout systems, hydraulic is the better of the two.

 

Damping – this is part of your suspension that does the most work, it controls the speed at which the compresses and extends (rebounds). Damping is most commonly done with oil. The oil has to pass through various holes and push various shims, creating resistance and controlling the speed at which your spring is moving.

 

Compression Damping – is about controlling the speed of your suspension when it compresses. It’s very important to have this set up correctly so that your suspension can absorb the force of a bump. It is also important to stop the suspension being compressed by the force of your pedalling action and body movement when pedalling, so that you get an efficient ride.

 

Rebound Damping – is about controlling the speed of your suspension when it extends. It’s very important to have this set up correctly so that your suspension rebounds fast enough to be able to absorb the next bump, but slow enough that it doesn't return with such force that it pushes you back up.

 

Low Speed Damping – this refers to damping (rebound or compression) which controls low speed movements. This has little to do with how fast you are going, it’s about how fast a force is applied to the suspension – an example of low speed movement would be movement from pedalling.

 

High Speed Damping – this refers to damping (rebound or compression) which controls high speed movements. Again this has little to do with how fast you are going, it’s about how fast a force is being applied to the suspension – high speed movements come from things like ‘square edge’ hits and even things like a small tree root will be controlled by high speed damping.

 

Linear Rate – this is the description of a suspension system that stays the same rate throughout the travel i.e. it could take 100lb to move 1 inch, 200lb to move 2 inches and 300lbs to move 3 inches and so on...

 

Progressive Rate – this is the description of a suspension system that increases the rate through the travel i.e. it could take 100lb to move 1 inch, 200lb to move 2 inches and 350lbs to move 3 inches and so on...

 

Falling Rate – this is basically the opposite to progressive, so rather than the rate increasing, it would decrease.

 

Spiking – this is the term used to describe when your suspension damper can’t cope with the severity of a bump and basically locks out and doesn't move! This is caused by poor damper design, when the oil can’t pass through the piston/shim or orifices, which regulate the flow of oil, fast enough and the suspension locks.

 

Nitrogen Charging – this is used on most rear shocks to apply pressure to the oil in the damper. Keeping pressure on the oil is very important to make the shock work correctly, on some shocks different pressures can make them perform differently. Air can be used, but nitrogen is less volatile, so it’s less affected by temperature change and subsequently gives more consistent performance.