There are quite a few bikers who regularly practice mountain biking and do not pay attention to the adjustments or maintenance of their mountain bike suspension system
. This is a serious mistake, which is unforgivable if it is due to neglect, since by dedicating just a few minutes a week or every two weeks to this aspect, it is possible to get the full potential out of the suspension, make the bike work better, and thus increase performance. In this article, we are going to focus on explaining five basic adjustments and maintenance tips for your suspension, both the fork and the shock absorber (if you have a full suspension MTB
). Remember that, in addition to these adjustments, it is advisable to carry out a thorough maintenance and cleaning of the suspension every year, either on your own if you have the tools and knowledge for it, or have it done in a specialized workshop. This period is shortened in the case of long-travel suspensions (enduro
and downhill
), which will be every six months.

The SAG or sagging

Adjusting the SAG or sagging of any suspension is essential, practically mandatory, if you want it to work reliably. It is the percentage of the shock absorber shaft that is inserted into the stanchion (which is the thicker lower shaft in the case of the fork, or the air sleeve in the case of the shock) when you get on the bike. Adjusting the suspension to have more or less SAG will determine how it behaves while riding. More SAG or sagging means a softer and more absorbent suspension, and less SAG means a harder and stiffer suspension.

Steps to adjust the SAG of your suspension

The adjustments should be made according to your weight, the suspension travel (or carrera, in the case of the shock), and the riding style. Every suspension brand and model has its own SAG tables and recommended air pressures, which are very useful as a starting point for adjustment. Although you can personalize these measurements depending on the type of terrain or your riding style. An example is the tables with SAG percentages and pressures from Fox.

Step 1: tools to adjust the SAG

To adjust the SAG of your suspension you will only need a specific suspension pump (a regular tire pump will not work) and a tape measure. The latter is not necessary if the travel or shock shaft comes with painted SAG guides (already common in mid-range suspensions). If the suspension does not have a rubber band attached to the shaft, you should tie a zip tie, without tightening it too much, so it can serve as a guide.

Step 2: open the compression dials

Leave the compression dials (usually blue) and rebound (red) of the suspension fully open.

Step 3: get on the bike

Dress in your usual gear, including shoes, helmet, and hydration backpack if you usually carry one. This will allow you to determine the correct SAG according to your actual weight during the ride or training. Get on the bike while stationary, leaning against a wall or with the help of another person, who will hold the bike by the handlebars.

Step 4: check how much the suspension has compressed

Once you are on and seated on the bike, the suspension will partially compress due to the extra weight of your body. This is the moment to get off and examine how much it has compressed. A measuring tape can be useful for this.

Step 5: calculate the SAG percentage

The suspension SAG will be the distance between the stop or seal of the shock absorber rod and the rubber or guide. If you have a 100 mm travel XC fork and the rod has compressed 15 mm, its SAG will be 15%. In the case of the shock absorber, you will need to consider the length of the carrera (length of the shock absorber rod). For example, in a cross country shock with a carrera of 52 mm, if it compresses 10 mm, the SAG will be 19%. The formula is simple: divide the distance the rod has compressed by the total suspension travel and multiply by one hundred.

Step 6: Adjust the SAG to your liking

If you want more or less SAG, depending on the manufacturer's recommendations or your own preference, you should insert the suspension pump into the valve of each suspension and inflate or release pressure. Once adjusted, get back on the bike to check the setting.

Step 7: Repeat this process once a month

Remember to write down the SAG percentage or the pressures of each of your suspensions in a note so you can remember them for periodic adjustments. As a general rule, it is recommended to check the SAG and pressure every month.

The suspension compression

Many mountain bike forks and shock absorbers have compression adjustment dials, which, when turned in one direction or another, will increase or decrease the stiffness, starting from a certain air pressure. For example, Fox has on its 32 fork for XC a blue dial installed on the superior part of the right stanchion with three positions: open (open), medium, and locked (firm). By turning the dial to one position or another, you get a softer suspension for obstacles or rougher terrain (open), stiffer, or even completely locked out. This last position is ideal for completely flat and firm terrain, such as asphalt sections or smooth tracks. Another compression adjustment dial option is remote lockout controls from the handlebar, which allow you to open or close the suspension without taking your hands off the handlebar to turn the dial. The design and operation of this dial varies depending on the brand or suspension model. RockShox, the other major global suspension manufacturer alongside Fox, offers dial options with several click positions (8 or 10) and also remote lockout controls. Likewise, in more radical discipline models, such as enduro, this dial is split in two, with one to adjust low-speed compression (behavior while pedaling) and the other for high-speed (obstacles and jumps).

Rebound

Another basic suspension adjustment is the rebound or return speed of the suspension travel. Like compression, enduro and downhill forks and shocks have low-speed rebound, which regulates pedaling behavior, and high-speed rebound, for obstacles and jumps. Likewise, rebound has its own adjustment dial with a certain number of clicks, from slower to faster. It is usually located at the bottom of the fork leg and on the superior part of the air sleeve on the rear shock. This way, you can adjust the rebound speed to your liking.

Progressivity or tokens

It is also possible to adjust the progressivity of the suspension at home, although this procedure is somewhat more complex than the previous ones. Progressivity refers to how quickly the suspension stiffens, depending on the pressure in the air chamber. This progressivity can be modified by adding or removing plastic pieces that vary in thickness depending on the brand or model, called volume spacers or tokens. The more tokens, the greater the progressivity of the suspension and the sooner it will stiffen. On the other hand, if the suspension uses all its travel and bottoms out, it is too soft and linear. In that case, you will need to insert a spacer to gradually use the entire travel. This way, you can avoid ending up in a dead spot of absorption and compromising bike control. Adding or removing tokens in the fork is a simple operation if you have a set of Allen keys and another cassette hyper glide. In this Core Bicycle video, they explain step by step how to do it: https://youtu.be/cpCEBsZKIms On the other hand, for the shock, it will be necessary to almost completely disassemble it to install the tokens, so we recommend taking it to a professional.

Coil suspension adjustment

The adjustments and modifications explained so far in this article refer to air suspensions, which are currently the most widespread in mountain bikes. But there are also setups with coil suspensions, especially the rear shocks of enduro and downhill bikes. Both are equally valid, although their behavior, maintenance, and adjustments are different. In the case of the coil, it is also possible to adjust both the SAG, through a nut with which we compress the spring more or less, as well as the compression or rebound. The coil suspension also has dials like those of air, which control the entry and exit of oil from a hydraulic cartridge, thus calibrating the speed and stiffness of the damping. In this video, Fox graphically explains how this system works through its famous X2 shock: https://youtu.be/oiANiwCzqZE In addition, the coil shock, although it does not have the almost millimetric adjustment of air, is nevertheless easier to maintain and does not have the problems of air pressure variation due to weather conditions. That is why it is an alternative to consider if you want efficient damping for practicing trail or enduro and do not want to go through the most cumbersome and expensive air suspension tune-ups every year.