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This is how it works: Structure of suspension fork and damper
Suspension forks and shocks work according to the same principle. The air pressure determines the spring stiffness and must be adjusted to the rider's weight. The compression and rebound stages regulate how quickly the suspension elements compress and rebound.
The list of these individual parts is valid for both the suspension fork and the rear shock:
- Standpipes / pistons
- Immersion tubes / Casting
- Rebound adjustment (red)
- Pressure stage adjustment (blue)
- Lockout (not on all models)
- Air valve
- Air chamber
- SAG display
Good suspension is the be-all and end-all of any mountain bike. If the suspension fork and shock are bumpy, too fast or too slow, control and comfort on the trail suffer massively. Customising the suspension elements is therefore an absolute must. The effort involved is manageable. The resulting increase in riding enjoyment is definitely worth familiarising yourself with the basic rules of suspension set-up. Regardless of the rear suspension system, model and brand, the adjustment rules work on the same principle for all mountain bikes. However, the required air pressure or spring stiffness for coil spring components varies depending on the model, individual body weight and riding style.
In our E-MTB special "All the facts for beginners" you will find even more useful information:
Air suspension vs. steel spring on the rear triangle
Steel springs are now only used in suspension forks on downhill and enduro bikes. This is because air is not only lighter, but the air chamber can also be easily adjusted to the rider's weight using a special shock pump. Depending on your riding style and personal preferences, you can experiment with different settings without having to replace a spring. The pressure should never be so low that the fork or damper bottom out on larger obstacles. If you pump up the suspension elements too much, you will give away unnecessary suspension travel. The suspension becomes less comfortable and, like a rubber ball, it tends to bounce and bump over obstacles rather than absorbing them gently. How smoothly the suspension works also depends on the damping. Valves regulate the flow of oil inside the fork and damper. When the suspension compresses, the compression damping valve opens and the suspension element can compress. On rebound, the valve closes. This prevents the suspension from springing back to its original position in an uncontrolled manner. This is regulated via the rebound damping.
Tip from Peter Nilges, BIKE test manager:
Volume spacers in the air chamber can be used to fine-tune the shock and suspension fork. They reduce the air volume and tighten the suspension - good against bottoming out.
Adjustment - the adjustment screws on the MTB suspension fork and damper
What use is the best fully if you don't really utilise the potential of the suspension? Customised setup is not magic. Here are the most important set-up points so that you can optimise your suspension fork and shock.
Air pressure
The higher the air pressure, the harder the suspension will be. It is important that the suspension elements are inflated at least enough to prevent them from bottoming out on rough obstacles or jumps. The right air pressure therefore depends not only on the rider's weight, but also on the terrain. The model of suspension fork or shock and the kinematics of the bike also play a role. Bike manufacturers provide specific tips for the appropriate air pressure for each model. To inflate and deflate the air in a controlled manner, use a Damper pump with pressure indicator.
Damping
It is connected to the suspension and dampens the vibrations at the suspension elements. The damping prevents the chassis from rocking, the bike from becoming uncontrollable and bouncing over obstacles like a rubber ball. An oil cartridge, usually in the right-hand side of the fork, is used for this purpose. During compression and rebound, the oil flow inside is reduced by valves.
Compression stage of the suspension fork
It regulates the speed of compression and is usually marked with a blue adjustment knob. The compression can be regulated quickly and easily using a rotary knob. High-quality forks and shocks often have two adjustment options.
Low-speed compression stage
Regulates the compression when the suspension is subjected to slow, soft loads, such as large bumps or berms. The harder (turn the knob towards "plus"), the firmer the suspension works.
High-speed compression stage
With fast, abrupt impacts, such as on root passages or when rolling over terrain edges, the high-speed compression stage is stressed. Turning the adjustment knob towards "plus" hardens the fork in such situations. Racers prefer a high compression stage in order to build up as much pressure as possible between the tyre and the ground. However, a high high-speed compression setting tires the upper body and arms on long descents.
Rebound of a suspension fork
The rebound (usually a red adjustment screw) regulates the speed of the rebound. A very slow rebound means that obstacles in quick succession can hardly be compensated for because the fork no longer reaches its full travel. If the rebound is completely open, the fork or damper return to their initial state too quickly. This can also lead to unsteadiness in the suspension.
What is the SAG or negative suspension travel?
The SAG or negative suspension travel refers to the distance by which the MTB suspension fork (or shock) compresses due to the weight of the rider plus equipment when stationary. The SAG is directly related to the air pressure. The SAG can be used to determine the required air pressure. As a rule of thumb, you can work with 30 per cent of the total suspension travel on the shock and 20 per cent on the fork. Forks and shocks often have a SAG scale, but always a rubber ring that indicates the negative suspension travel.
Platform damping
Many shocks and forks have a lever with which the compression damping, i.e. the compression during the ride, can be regulated in predefined stages. Activated: to prevent bobbing and for more effective pedalling uphill. Open: for full suspension performance downhill.
Lockout
A mechanism that largely locks the fork or shock via a lever on the suspension element or a remote control on the handlebars. This also helps you to pedal fully uphill without bobbing.
Electronic running gear
In the meantime, manufacturers such as Fox (Live Valve) or Rockshox (Flight Attendant) also with suspension elements that can be electronically controlled and individually adjusted on the basis of digital data. You can find an interesting comparison of both systems in this article.
How to set the shock correctly on a mountain bike
Setting up a fully rear suspension correctly is not much more complicated than inflating a tyre. You can adjust the air pressure of the rear suspension to your body weight and regulate the damping according to your riding style and terrain with a few simple steps.
You don't have to make a science out of adjusting the shock and suspension fork. With a few simple setup rules, you can get a lot out of any fully suspension. - Dominik Scherer, BIKE Lab, Test and Technology
The perfect suspension fork setup
Only with the right individual setup can you get the optimum performance out of the suspension fork. Proper basic adjustment with the shock pump takes no more than five minutes. Even more fine-tuning is possible with volume spacers. This is how you can optimise your suspension fork on your mountain bike.
