Practical guide to adjusting your mountain bike suspension: shock and fork – Epic Bike Store

Introduction

Properly adjusted suspension is essential to maximize the comfort and performance of your mountain bike. This guide will show you how to properly adjust a rear shock and suspension fork using a simple sequence.

Part 1: Adjust the shock absorber (the rear “shock”)

1. The initial pressure

Start by inflating the shock to the recommended pressure for your weight. This forms the basis of your settings.

Consult the manufacturer's manual : Consult your bike manufacturer's manual for initial pressure recommendations. If no recommendations are available, also check the shock manufacturers' documentation.
Adjusting the initial shock pressure : Generally, the initial shock pressure can be adjusted based on your weight. Use your weight in pounds (lbs) or twice your weight in kilograms (kg) as a starting point.

Initial pressure of a shock absorber — Initial pressure for a pilot of... 197 pounds.

Note that this initial pressure is simply used to move on to the next step, adjusting the SAG. It is important not to skip any steps and to ride directly with this initial pressure.

2. SAG adjustment

SAG, or static sag, is crucial for a properly tuned suspension. To measure SAG:

Make sure all compression settings are fully open.
Place the bike on a flat surface.
If a measuring ring (an o-ring ) is installed on the tube, reset its position.
Get on the bike with your full gear, get into your basic position and push down your suspension a few times.
Make sure the measuring ring (an o-ring ) is properly positioned against the shock absorber seal and gently get off the bike, without compressing the suspensions.
Measure the sag and adjust the air pressure to achieve 25% to 30% of the total travel or the value recommended by your bike manufacturer. With the exception of cross-country bikes, most manufacturers recommend a sag between 28 and 30% for all other types of bikes.
Adjust the SAG by adding or raising air in ~5 psi increments until the desired SAG is achieved.

💡 The importance of SAG in the context of mountain biking

SAG, or static sag, is a crucial element for your mountain bike's suspension. It represents the percentage of suspension travel used when the bike is supporting the rider's weight in a normal riding position. Setting sag correctly allows the bike to maintain optimal geometry under all conditions.

Think of your bike as a balance between stability and responsiveness. Without proper SAG, the suspension could be too stiff or too soft, compromising handling and comfort. With properly adjusted SAG, the bike is able to adapt to changes in the terrain, absorbing small bumps and impacts while maintaining its original geometry. This means the frame and fork angles remain relatively constant, ensuring a more predictable and stable ride.

In other words, SAG allows your mountain bike to perform as intended, maintaining the handling and control characteristics that the engineers designed . That's why it's essential to take the time to properly adjust SAG, to take full advantage of your bike's capabilities on all types of terrain.

3. Adjusting the rebound (the trigger)

Most shock absorbers have only one rebound setting ( slow speed rebound ).

Consult the documentation : The first step in adjusting rebound is to consult the manufacturer's documentation, such as Fox's manuals or RockShox's Trailhead app, for starting point recommendations. If this information is not available, start at the mid-stroke (for example, if the shock has 20 clicks of rebound, start at 10 clicks).

💡 Understand how the adjustment dials work

The adjustment dials on your suspension work much like a faucet that controls water flow. Think of the oil in your cartridge as water in a hose. The more open the faucet is, the more freely the oil can flow, thus providing less resistance.

Compression : If the "tap" is open, oil flows easily, providing less support and making the suspension softer. Conversely, if the "tap" is closed, less oil circulates, increasing support and making the suspension firmer.
Rebound/Rebound : Similarly, an open "tap" allows the suspension to return quickly after a bump, making rebound faster. A closed "tap" slows the return, as the oil circulates more slowly, which slows rebound.

Generally speaking, turning the control knobs clockwise closes the circuit, increasing resistance, while turning them counterclockwise opens it, reducing resistance. Obviously, this is a simplification, and it is always recommended to consult the manufacturer's manual for precise adjustments.

Slow Speed Rebound Adjustment : If the shock rebounds too quickly after compression, you need to close the rebound circuit further. If the rebound is too slow and the shock does not return to its original position after compression, you need to open the rebound circuit further. For most manufacturers, turning the control knobs clockwise closes the circuit while turning it counterclockwise will open it. If in doubt, refer to your manufacturer's manual.

High Speed Rebound Adjustment : If available, adjust the high speed rebound to handle high speed impacts and maintain better traction on rough terrain. Adjust this setting after you have found a good low speed rebound setting.

4. Compression adjustment

Most shock absorbers have a single compression setting (low-speed compression). High-end models may have high-speed compression settings.

Slow- speed compression : Set the low-speed compression first. Start in a middle position and adjust as needed. If the suspension is too stiff and lacks sensitivity, reduce the compression by opening the circuit. If it is too soft and dives too much, increase the compression and close the circuit. As with rebound, turning the controls clockwise usually closes the circuit, while turning them counterclockwise will open it. If in doubt, refer to your manufacturer's manual.

High Speed Compression : If available, adjust the high-speed compression to handle big impacts and aggressive descents. This helps prevent bottoming out and improves control over large obstacles.

💡 Understand the concepts of high speed and low speed in the context of expansion and compression

When talking about high speed and slow speed in the context of mountain bike suspension rebound and compression, it is important to understand that these terms do not refer to the speed at which you are riding, but rather to the speed of the suspension compression and rebound, the speed of oil movement in the circuits.

Slow speed refers to slow suspension movements, often caused by actions like pedaling, braking, or weight transitions. These movements occur when the suspension shaft moves slowly within the shock or fork body. For example, when you lean forward to descend a hill or brake before a turn, the suspension slowly compresses to accommodate these changes.

High speed , on the other hand, refers to rapid suspension movements, such as those caused by sudden impacts such as large rocks, roots, or steep descents. Here, the suspension rod moves quickly within the shock or fork body to absorb these rapid, intense shocks. This setting allows the suspension to react quickly to large impacts, thus preventing bottoming out and improving control on rough terrain.

So, high-speed and low-speed settings fine-tune suspension response based on how quickly forces act on it, not how fast the bike is moving . By understanding this nuance, you can better tune your suspension for optimal performance on various terrain types and riding conditions.

Part 2: Adjusting the Suspension Fork

1. Basic setting

Start by inflating the fork to the recommended pressure for your weight.

Check the manufacturer's manual : For forks, there is often a recommended pressure chart on the lower legs . If not, start with a pressure equal to your weight in kilograms or half your weight in pounds (lbs).

2. SAG adjustment

SAG is also crucial for the suspension fork. Follow the same steps as for the rear shock to measure and adjust the sag.

Make sure all compression settings are fully open.
Place the bike on a flat surface.
If a measuring ring (a o-ring ) is installed on the tube, reset its position.
Get on the bike with your full gear, get into your basic position and push down your suspension a few times.
Make sure the measuring ring (an o-ring ) is properly positioned against the shock absorber seal and gently get off the bike, without compressing the suspensions.
Measure sag and adjust air pressure to achieve 15% to 20% of full fork travel, or adjust to your preference by adding or raising air in ~5 psi increments.

3. Adjusting the rebound (the trigger)

Most forks have only one rebound adjustment (low speed rebound).

Consult the documentation : Consult the manufacturer's documentation for starting point recommendations. If the information is not available, start at the mid-range and adjust to your preference.
Slow Speed Rebound Adjustment : If the fork rebounds too quickly, reduce the rebound speed (turn the knob clockwise). If the fork does not extend quickly enough, increase the rebound speed (turn the knob counterclockwise). For most manufacturers, turning the control knobs clockwise closes the circuit while turning them counterclockwise will open it. If in doubt, refer to your manufacturer's manual.

High Speed Rebound Adjustment : If available, adjust the high speed rebound to better handle high speed impacts.

💡 Understand how the adjustment dials work

Compression : If the "tap" is open, oil flows easily, providing less support and making the suspension softer. Conversely, if the "tap" is closed, less oil circulates, increasing support and making the suspension firmer.
Rebound/Rebound : Similarly, an open "tap" allows the suspension to return quickly after a bump, making rebound faster. A closed "tap" slows the return, as the oil circulates more slowly, which slows rebound.

4. Compression adjustment

Most forks have a single compression adjustment (low-speed compression). High-end models may have high-speed compression adjustments.

Slow speed compression : First, adjust the low-speed compression to your feel. If the fork is too stiff, reduce the compression by opening the loop. If it is too soft, increase the compression by closing the loop. As with rebound, turning the control knobs clockwise closes the loop, while turning them counterclockwise opens it. If in doubt, refer to your manufacturer's manual.
High Speed Compression : If available, adjust high speed compression to better handle big impacts and aggressive descents.

5. Testing and Adjustment

Field Test: Test the bike on different types of terrain (climbs, descents, rough terrain) to evaluate the performance of the settings.
Fine Adjustments: Make fine adjustments as needed, returning to the rebound settings if necessary before adjusting the compression again. Repeat this process until you find the optimal setting.
Record your settings: It's essential to record your settings so you can track them over time and identify what works well and what doesn't. Use a sticky note, a note on your smartphone, or any other method to record your settings and impressions. This will help you more easily associate the sensations on the bike with the adjustments you've made.

Conclusion

Following these steps will help you optimize your suspension settings, improving your performance and comfort on the trails. Remember to consult the manufacturer's documentation for specific recommendations and always adjust your settings based on your riding experience. Recording your settings and impressions will allow you to continually fine-tune your suspension for optimal performance.

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