How to choose your MTB shock absorber?

A key element of a full-suspension frame for precise and comfortable handling, the MTB shock absorber must be chosen carefully. Increasingly sophisticated and high-performing, the choice is only made more complex. Here is a guide to help you find the one that suits you best.

Standards

You will not necessarily be able to fit any shock absorber on your frame. Beyond the choice of technology (air, coil spring...), you will need to comply with the following points based on compatibility with your frame:

• The fixing centre distance a: distance between the 2 anchor points
• The stroke: the travel over which the shock absorber will work
• Size/shape: some frames do not accept an overly bulky model
• Setting (or factory configuration)

Types of shock absorbers

A suspension is always made up of 2 distinct elements:

• The spring — air b or coil c;
• The damping unit, always hydraulic, housed entirely within the body of the shock absorber or partially offset into a reservoir or "piggyback" c1.

Air springs are lighter and offer what is known as progressive behaviour. They allow for simpler and more precise adjustment relative to the rider's weight using a high-pressure pump.

Some brands offer the same model in different air chamber sizes. The larger the air volume, the more linear your shock's behaviour will be, and the better it will handle temperature variations caused by use. The smaller the air volume, the more progressive your shock will be.

Coil spring shock absorbers are more sensitive to small impacts and offer what is known as linear behaviour. Their reliability is their strong point, but they are heavier. They require a spring suited to the rider's weight (this is not included as standard).

The hydraulic unit's function is to manage the compression speed (or dive) d and rebound e (or return) through the metering of the oil inside. Some models have a piggyback reservoir that not only provides a greater oil volume for better management of temperature variations, but also allows for finer adjustment of compression and rebound.

The setting (in French "configuration") is the preparation of your shock absorber, carried out at the factory by the manufacturer, in order to adapt it to the kinematics of your frame. This setting covers two parameters (compression and rebound) and is generally done across three levels.

To choose the right setting for your frame, it is best to refer to the frame manufacturer's information.

Which shock absorber for my discipline?

• Trail Riding
  When out on a leisure ride with your trail MTB, choose an air shock to easily adjust it to your weight, and a standard air volume for greater versatility. For the hydraulics, keep it simple: a lockout for very smooth sections or climbs, and a rebound adjustment will be more than sufficient.

• Cross-Country
  Are you more of a Cross-Country rider on your hardtail MTB? Go for a lightweight air shock with the smallest possible air volume to limit losses caused by the pumping phenomenon. A handlebar lockout if possible and a rebound adjustment are essential for sporting use.

• All-Mountain
  For All-Mountain riding on a full-suspension MTB, the performance and lightness of an air shock will be a real asset. Preferably with a standard or even large chamber to maintain perfect performance on descents. Rebound adjustment is essential and compression adjustment is recommended to adapt to all types of trails. A lockout, on the other hand, is not necessary.

• Enduro
  When it comes to Enduro, an air system will again be the most appropriate choice to optimise performance, with a large chamber to maintain perfect behaviour on descents. Rather than a lockout, opt for compression and rebound adjustment to adapt to the various characteristics of the terrain. In addition, a piggyback version will also be an advantage (if your frame allows) in order to improve the reliability of the hydraulic support on fast, rough descents.

• DH / Freeride
  In DH / Freeride, coil spring shocks with a piggyback reservoir are king for obvious reasons of robustness and good management of temperature variations. However, air systems, which are increasingly high-performing, are beginning to make their mark in this discipline. One, or even two, compression adjustments (high and low speed) are necessary, as is rebound adjustment.