More control and comfort: How to set up your mountain bike suspension correctly
Good suspension is the key to maximum control and comfort. If the suspension fork and shock work insensitively, too quickly or too slowly, off-road performance suffers. Customising the suspension elements is therefore an absolute must. With the right know-how, the effort is manageable. Before we get into the details, it's worth taking a look at the basics. What are the lower tube and upper tube, where are the valves located, which button does what?
Chassis lexicon: What is what?
- Standpipes / pistons
- Immersion tubes / Casting
- Rebound adjustment (red)
- Pressure stage adjustment (blue)
- Lockout (not on all models)
- Air valve
- Air chamber
- SAG indicator (rubber ring)
SAG stands for the negative suspension travel, i.e. the amount by which the fork or shock absorbs the weight of the rider plus equipment when stationary. The SAG can be adjusted via the 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.
Not on all models: Platform/lockout
Here, the spring movement can be significantly restricted for greater efficiency using a lever on the fork or damper or even by remote control. If the suspension elements are then completely blocked, this is referred to as a lockout. On many touring bikes, the spring movement is only slowed down slightly by increasing the compression stage, for example to prevent the suspension from bobbing uphill. This is referred to as a platform.
Why do you need this? A bobbing chassis can interfere with pedalling, and efficiency also increases slightly if bobbing is eliminated. However, many modern bikes hardly bob at all, even with full suspension. A hard platform is mainly found on cross-country bikes to firm up the suspension for hard sprints. Normal touring bikers generally do not need this feature.
MTB Suspension Setup: The basic principle
Regardless of the rear suspension system, model and brand, the adjustment works on the same principle for all mountain bikes. The required air pressure or spring stiffness is adjusted to the rider's body weight and riding style.
Rebound/rebound and compression/compression are then adjusted. Steel springs are now only used in rare cases. Air suspensions are not only lighter, they can also be easily adjusted to the rider's weight using a special damper pump.
Depending on your riding style and personal preferences, you can experiment with different settings. The pressure and therefore the spring rate should never be so low that the fork or shock permanently bottom out. If you pump up the suspension elements too much, you give away unnecessary suspension travel, which reduces traction and increases fatigue when riding.
How smoothly the suspension works also depends on the damping. Valves inside the fork and damper regulate the oil flow. The compression damping is responsible for the compression speed and the rebound for the extension speed of the suspension elements.
Air pressure, rebound, compression, spacer: 4 steps to success
1. air pressure & SAG
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 and riding style. 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. A shock pump with a pressure indicator is used to inflate and deflate the air in a controlled manner. Basic rule: 15 - 20 per cent SAG at the fork, 25 - 30 per cent SAG at the rear.
2nd rebound (red)
The rebound (red adjustment screw) regulates the speed of the rebound. A very slow rebound means that obstacles in quick succession can hardly be equalised because the fork no longer reaches the full suspension travel.
If the rebound is completely open, the fork or damper will return to their original state too quickly. This also leads to unsteadiness in the suspension and, in extreme cases, to a loss of traction.
3rd pressure stage (blue)
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.
The low-speed compression stage regulates the compression when the suspension is under slow load, for example on large bumps or berms. The harder the compression (turn knob towards "plus"), the firmer the suspension works.
With fast, abrupt impacts, such as on root passages, hard landings 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 setting 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.
4. volume spacer
With the help of these spacers, the air chambers of the fork and shock can be reduced in size. A smaller air volume increases the progression towards the end of the spring travel. If the suspension bounces too often despite the correct SAG, the air chamber can be reduced in addition to increasing the compression damping. If, on the other hand, you remove any installed volume spacers, the suspension travel can be better utilised and the suspension is potentially more comfortable.
Troubleshooting: Sensitivity & basic damping
Have you tried everything and the suspension is still hard as a rock and uncomfortable? Unfortunately, there is little you can do to influence the response behaviour of the suspension elements themselves. In the event of wear or heavy soiling, a service can help to restore the original condition. However, inexpensive suspension elements often have a lot of friction between the various components due to imprecise fits. A service can only help to a limited extent.
It is also possible that the rebound and compression damping cannot be adjusted correctly. Very light riders in particular need very little air pressure/spring stiffness and often find their suspension elements overdamped. This becomes most obvious when the suspension does not rebound quickly enough despite the rebound being fully open.
With some cheaper Suntour suspensions, we have already noticed this effect even with normal rider weights. for example when testing the Merida eOne-Eighty. However, even high-quality suspension elements are occasionally affected by over- or under-damping due to series variation. In this case, the only solution is to replace the spring elements or a shim tuning from a professional, especially for very heavy or light riders.
BIKE conclusion: Suspension - Set it and forget it?
A good suspension set-up is as important for safety and riding enjoyment on the trail as the correct tyre pressure. So it's absolutely essential! It's worth experimenting a little with the parameters. Also for a better understanding of the suspension setup as a whole. Important: The damping in particular should always be adjusted depending on the trail and temperature. We have written more specifically about fork and shock setup in separate articles. - Adrian Kaether, Editor Test & Technology
