How to Adjust Front Shocks on a Mountain Bike?

You have made an excellent choice by purchasing a full-suspension mountain bike, but to achieve the best performance level with it, you will need to fine-tune its suspension and shock components. With your full-suspension bike, you’ll navigate technical terrain more easily, with less effort, and have better traction on hard or soft surfaces than with a hardtail.

The behavior of a mountain bike’s front suspensions will depend on the adjustment you make. An incorrect adjustment will give you average results and worse performance. In this regard, this article shares everything you need to know about front suspensions.

What are Front Suspensions in a Mountain Bike?

The suspensions of a mountain bike are undoubtedly very important to have a better performance on the descents. That is why taking care of them is essential to function properly.

A good mountain bike experience depends not only on the model of the mountain bike and its components but also on the necessary maintenance and adjustments that the user makes for them to work optimally. The two main mountain bikes’ suspensions units are the front shocks and forks.

The appearance of suspensions was a revolution for mountain biking. Thanks to the fork and shock absorber that offer optimal pleasure in riding mountain bikes.

Unfortunately, many mountain bikers ride on poorly adjusted suspensions despite successful suspensions. Before you have your suspensions prepared, you have to make sure that they are properly adjusted. And this rule applies even to very good riders!

Before adjusting the mountain bike shocks, you must know all the elements and factors that intervene in the correct functioning of the mountain bike front suspensions and how they work.

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How Does the Front Suspensions of a Mountain Bike Work?

Your mountain bike’s front shocks absorber and fork work globally in the same way: a spring deforms to absorb the energy of a shock.

Type of Spring

There are two types of spring for these suspensions: the coil spring and the pneumatic spring. The first one is simpler, often less expensive, limits friction, and does not change its behavior on long descents. The second is a little more difficult to adjust and maintain, but it is lighter. Its good adjustment makes it suitable for both featherweights and heavyweights.

Travel

The main objective of front forks is to reduce the impacts and vibrations of uneven surfaces, compressing or extending the length of their arms in a controlled way. The shock is slightly different: the shock, in addition to compressing itself, moves the rear triangle of your bike’s frame.

Sag

Sag is the travel of the coil or air spring when cushioning a shock. It is the percentage of depression of the suspension when the mountain biker climbs on the bike.

The Hydraulic System

The hydraulic system is present in most mid-range and high-end shocks and forks. This cartridge is made to slow down the movement speed in the sheaths to maintain control of the bike. This is what limits the rebound of the suspensions following the spring effect.

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The Different Mountain Bike Suspension Settings

General

We generally find the same adjustment possibilities on the front shocks or suspension fork. It depends on the level of range and the practice for which the mountain bike is intended. Here are the three main settings available on a good part of the production:

• the preload or SAG: It corresponds to the depression of the suspensions under the weight of the pilot,
• compression: speed of depression of the suspension during an impact,
• rebound: speed of return of the suspension to its initial position after a compression phase

Other available settings can be:

• travel: available only on the forks, this setting reduces the travel of the forks,
• the blocking or pedaling platform: It allows you to lock or harden the compression to avoid pumping of the suspension,
• The negative air chamber: It allows you to adjust the sensitivity of an air fork on small shocks.

The purpose of these settings is to adjust the suspensions to your weight and level of practice to absorb shocks without causing any parasitic effect.

Specificities of the Hydraulic Adjustments

For the rebound and compression settings, we intervene on the hydraulic part of the suspensions. The settings affect the passage of rolling oil through a piston.

The hydraulic settings are more complicated to adjust than the Sag because they require a certain feeling of the work of the suspensions. Rebound is a little easier to feel than compression.

There may be settings differentiated between high and low speeds (corresponding to the speed of suspension movement). These adjustments are quite common for compression on high-end shocks, rarer for a rebound.

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Understanding Settings of Mountain Bike’s Front Suspensions

To adjust the suspensions, you must follow a specific order:

• Do the SAG,
• Adjust the trigger,
• Adjust compression.

This order is important because your new SAG value (e.g. +20 psi or 1 turn of spring preload) will modify your hydraulic speeds if you adjust your hydraulics first and then your SAG. The spring being firmer, there will be less compression phase, and the return speed will be faster.

The Criteria to Adjust Front Shocks

Even if there are adjustment principles, your sensations and riding style will be greatly important. Adjustments may be satisfactory in static but unsuitable in the field because of:

• the bike’s equipment: an aluminum frame with aluminum wheels will not react in the same way as a full carbon mountain bike (wheels + frame) which will be much stiffer, therefore more intolerant and uncomfortable,
• the terrain on which you ride: rocky ground vs. carpet of larch needles,
• climatic conditions: hard or frozen ground vs. mud,
• your physical condition or motivation level
• the Kinematics of your mountain bike:  the different types of frame kinematics affect the rear damping. A kinematic can be linear (mono-pivot) or progressive (virtual pivot point VPP, 4-bar linkage)

Therefore, the following advice serves as a starting point, but it is the field tests and your feelings that will validate your settings. It’s important to find mid-range settings that work for most riding conditions. It only remains to refine according to particular conditions.

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Adjusting Your Sag

The adjustment of the SAG makes it possible to adjust the suspensions to the pilot’s weight by playing on the spring. It is a ratio expressed as a percentage compared to the suspension’s travel.

As you know, there are two types of spring (pneumatic and helical), the adjustments are therefore made accordingly. In addition, sag is always higher on the shock than on the fork. You have to find the right balance between the front and the rear of the bike.

For the rear suspension, the travel of the rear wheel does not correspond to the travel of the shock absorber. There is a reduction due to the positioning of the shock absorber. Therefore, the percentage expressed corresponds to the depression of the shock absorber rod under your weight, compared to its original position.

The Adjustment Procedure

Have another person help you hold the bike and measure the sag values, or use the O-rings as indicators and stand next to a wall to lean. You will need:

• one meter,
• a calculator
• O-rings on the suspensions
• a high-pressure pump for air spring suspensions.

Here are the different steps:

1. Determine:
2. the travel of your fork (normally you should know this value)
3. the stroke of your air shock
4. the center distance of your spring shock
5. Open the compression settings.
6. Inflate the air suspensions to the manufacturers’ recommendations. For spring suspensions, screw in at half the setting.
7. Place the travel sight O-rings against the fork oil seals or the shock body on an air shock.
8. Have the person hold the bike or lean your shoulder against a wall.
9. Get on the mountain bike in riding gear.
10. Get into a standing position with the pedals horizontal.
11. Run the suspensions 2-3 times.
12. Then stabilize yourself in a standing position with your shoulders over the handlebars.
13. Lower the O-rings against the lower legs/shock bodies.
14. For a spring shock, the person must measure the distance between the eyelets.
15. Get off the bike without pushing back the suspensions.
16. Measure the displacement of the O-rings from their initial position and note this value in millimeters.
17. Adjust the obtained SAG according to the desired percentage. Inflate or deflate an air spring. Screw or unscrew the preload adjuster of a coil spring.
18. Recheck the SAG while still operating the suspensions. This allows you to balance the positive and negative air chambers (if present), allowing you to exceed the trigger threshold in the event of strong friction.

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Setting the Trigger

Rebound is the second adjustment after SAG. In most cases, the trigger is materialized by red knobs.

Almost all front shocks and forks have a single rebound setting, managing low speeds corresponding to the beginning/mid-stroke. The management of high speeds is done internally via the valves.

The trigger’s adjustment depends on:

• Your level: a beginner will have a more slowed trigger than an expert because his speed of passage in the rutted areas will be lower.
• Your riding style: an aggressive rider will want a lively rebound to get out of a lift quickly or for better momentum on jumps
• Your playing field: a brittle ground will require a little faster relaxation.

The Adjustment Procedure

If they exist, base yourself on the recommendations of the brand to start, then adjust to +/- 2 to 3 clicks. The return speed should be snappy enough without feeling like a slamming suspension. For suspensions with high and low-speed rebound settings:

• Low-speed rebound: the adjustment follows the same principle as before, but it can be a little more open, making the mountain bike livelier.
• High-speed trigger: the setting must be slower than the low-speed trigger to avoid racket hits on a jump landing.

To check the static rebound adjustment for a shock absorber, pressure is applied to the saddle. In general, we put a little less relaxation in the back than in the front. With practice, we adjust the trigger almost correctly, even in static. But the validation will always go through the field.

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Adjust Compression

Compression is the most complex adjustment because it is difficult to feel in static form. It is materialized by blue color settings in most cases.

From the mid-range, the suspensions have a compression setting. The high and low-speed settings are present only on certain models of high-end and rather Gravity-oriented forks and shock absorbers.

The different types of settings:

• A single compression setting: it corresponds to the low-speed compression setting.
• 2 or 3 position adjustment: some brands have simplified this adjustment by offering only 2 or 3 positions: open, pedaling platform (Propedal) and blocking (or almost blocked). The low-speed compression is hardened during the climbing phase or on rolling terrain for maximum performance. In contrast, we will open the compression downhill or rough terrain for maximum comfort and grip.
• Two separate high and low-speed compression settings adjust the suspensions perfectly, but the setting is more complex. The adjustment of the high speeds plays on the comfort and the dynamism of the bike. It isn’t easy to feel in static and is judged while driving.

Tips for Adjusting Your Mountain Bike’s Front Suspensions

• If you modify your SAG after making all the adjustments, you will have to adjust the rebound and the compression again by a few clicks because the spring preload affects the hydraulics.
• Never ride on the extreme settings: always go back one notch because it tends to crimp the adjustment rods in the cartridge. The adjustment is then blocked, and if you force it, the rod can break, and you have to change the hydraulic cartridge.
• With the development of pedaling platforms, preference should be given to settings for downhill orientation because the Propedal will allow a suitable adjustment for the pedaling zones.
• Define the efficiency of your adjustment knobs. It is necessary to define if 1/2 clicks impact the setting or if it is necessary to work by several clicks with each modification of the setting. Indeed, the ranges of settings can be very variable from one brand to another.
• Remember to tune your fork and shock to have a balanced mountain bike.
• Do not copy your friend’s settings: for the same front shocks (same center distance, same model), you can have completely different internal settings (compression and rebound valves).

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Conclusion

Adjusting your front shocks is a crucial step in setting up your mountain bike, but it is also the most difficult. So you have to spend time and work methodically. After an initial setting based on the recommendations of the brands, you should only change one setting at a time in order to really feel what your different settings are playing on. It’s really the feeling on the ground that will make your suspensions be adjusted to your mountain bike and riding style.