Before you jump on your new mountain bike and start ripping the trails, it’s vital to set up your bike’s suspension. Failure to do so will result in a rough ride that could end in a crash. At the very least, the suspension will not perform as it should.
Every rider is different — size, weight, riding style, and preferences all play a role. It is essential to set up your bike’s suspension to accommodate you and the trails you ride.
What You’ll Need
Fortunately, the supplies you need for setting up mountain bike suspension are minimal. A shock pump is a must. Despite suspension manufacturers using the common Schrader valves, you cannot use a standard floor pump to add air to your suspension.
The only other tool you’ll need is a ruler, unless you have RockShox suspension. RockShox uses markers on the side of their shocks and forks, eliminating the need for measurement.
Understanding Mountain Bike Suspension Settings
Most modern trail bikes are full suspension, meaning they have suspension in the front and rear of the bike. A mountain bike’s rear suspension is a shock, and the front suspension is a fork. There are two styles of shocks for a mountain bike — air and coil. For this how-to, we will be discussing suspension setup on an air shock and fork.
There’s a lot to consider when setting up a mountain bike suspension. How much air should you put in? What sag do you want to run? What about your high- and low-speed compression? Rebound? Don’t worry, I’ll explain each setting and adjustment, and how each change will affect how your bike rides.
It is also important to note that not every fork and shock will have the same settings and adjustments. While I will cover the most common suspension settings, don’t be alarmed if your suspension doesn’t have high-speed compression, for example. Settings may vary by brand and depend on the suspension tier your mountain bike came with.
Furthermore, high- and low-speed settings can be a bit confusing. The “speed” we are talking about here has nothing to do with how fast or slow you are going on the trail. Instead, they correspond to the speed at which your suspension is compressing and rebounding.
While the following is an overview of setting up a fork and shock, they should be done one at a time. Start with the fork and complete the entire process before moving on to the shock.
Setting Sag
Sag is how much the suspension compresses under your riding weight — clothes, packs, and helmet included. This is a static number, taken on a flat surface and not while you are riding down the trail or bouncing up and down.
Most bikes have a recommended sag between 20 and 30 percent. You achieve your desired percentage by adding or removing air from the suspension. How much air? Fortunately, there should be a chart near the bottom of your fork corresponding to air pressure and rider weights. While no such chart will be found on your shock, a great starting place is to match the air pressure with your body weight.
Step 1: Add the recommended air to either your fork or shock, one at a time. For every 50 psi of air pressure you add to your suspension, pause and compress the suspension roughly ten times. Allowing the fork and shock to cycle through their travel enables the air to equalize in the chambers.
Step 2: Find a wall to lean against to help with stability and ensure the rubber O-ring on the suspension is at the bottom of its travel. Wearing your complete riding kit, climb onto the bike, using the wall for stability, and allow your body weight to compress the suspension, moving the O-ring.
Step 3: Carefully climb off the bike, ensuring the O-ring doesn’t move from its position. Using a ruler, measure the distance the O-ring has moved compared to the total travel of the suspension. Comparing the two will allow you to find the percentage of sag. Remove or add air depending on your desired sag percentage.
Adding air will have your suspension closer to the 20 perfect end of the spectrum, creating a stiffer suspension feel. Less air will get you closer to 30 percent and a softer overall ride. Setting sag is the foundation of a good mountain bike suspension setup, so take your time.
Compression
After you set the sag on your fork and shock, the next thing to adjust on your mountain bike’s suspension is the compression settings. Think of compression as a way to fine-tune how soft or firm your suspension is during high- and low-speed impacts.
Most compression dials or knobs will have a plus and minus symbol. Turning the dial toward the plus sign closes the system, allowing less oil to flow through the suspension, adding compression resistance. Moving the dial toward the minus symbol opens the system, removing compression resistance.
Depending on the suspension you have, there may be adjustments for both low and high speeds. If your suspension doesn’t have one of the settings I’m about to cover, fear not. The suspension manufacturer incorporated the specific setting you are missing internally with a more neutral tune.
Step 1: Find the dial or knob that says HSC — high-speed compression. Start by turning it counterclockwise until it is fully open. Slowly turn it clockwise, counting the clicks as you go. This is how many compression adjustments are available, which is good to know for later fine-tuning.
Step 2: Turn the dial counterclockwise to reopen the system. For the fork, consult the chart on the lower leg. Start by turning the dial clockwise the recommended number of clicks. For the shock, the suspension manufacturer will provide a chart on their website.
Step 3: Repeat this process for low-speed compression, looking for the dial labeled LSC.
If your compression is too firm, you won’t use all of your suspension’s travel, resulting in a harsh ride. Too soft, and you won’t get the support needed, bottoming out where you shouldn’t. Remember, if your suspension has both HSC and LSC, you can fine-tune how your suspension responds to fast and slower impacts by utilizing those adjustments
Rebound
Rebound is how quickly the suspension returns to its full travel. As with compression, there are instances of high-speed and low-speed rebound. Again, high- and low-speed do not correspond to how quickly you are riding down the trail. Also, depending on your suspension, you may not have both high- and low-speed rebound settings.
Step 1: Find the rebound knobs or dials, starting with HSR — high-speed rebound. Turn the dial in the direction that makes the suspension rebound more slowly until it stops. Now, turn the rebound in the opposite direction and count clicks to determine the rebound adjustments available.
Step 2: Return the rebound dial to its slowest (closed) rebound setting. Consult manufacturers’ charts for their recommended rebound settings, and adjust accordingly by opening the rebound the recommended number of clicks.
Step 3: Repeat for low-speed rebound, looking for the dial labeled LSR.
If your rebound is too fast, it can pop you unpredictably off jumps and obstacles. Or, if it is too slow, it can pack up, never returning to its full travel, creating a harsh ride with little to no traction.
Minor Adjustments
These factory-recommended settings are an excellent starting point. Your riding style and local trails should dictate how your suspension performs, so don’t be afraid to make adjustments. Once you’ve completed the initial setup, it’s time to adjust your suspension on the trail further.
Find a descent with a good mix of terrain — rocks, roots, and jumps or drops if available — and ride the section multiple times. Tune into how your suspension is performing as you descend. If the bike is bouncing around a bunch rather than tracking the ground, you may need to open your HSC or slow your rebound. If you bottom out hard going into the lip of a jump, increase the LSC.
Change one thing at a time. Test ride, change, test ride, repeat. It may take a day of riding, but it will be worth it in the long run. See you on the trails!
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