How To Adjust Mountain Bike Suspension

Ultimate Guide on How To Adjust Mountain Bike Suspension

Getting the right suspension adjustment can make or break your bike performance. Why?

Because your bike is designed to move along the frame with the changing terrain and every subtle imperfection in that frame requires just enough suspension to give the smoothest ride you’ve never imagined. 

To further guide you on tweaking your MTB suspension setup, you’ve come to the right page. We’ve compiled all the technical info you need to know to get riding faster and more comfortable.

How To Adjust Mountain Bike Suspension

Set the Sag

Do you want to know the secret to achieve the optimal performance of your MTB suspension? Then set the sag correctly!

Learn the basic anatomy of your bike and the importance of sag. Who doesn’t want their bike to be at its best when tackling steep hills or fast descents? In order for your suspension to absorb small bumps effectively, you need to set a certain amount of air pressure inside the shock.

Every time you hit something, your shock and fork compress and absorbs the energy coming from the impact. By then, the energy will be released. Then you’ll regain the momentum and can continue on your ride.

The suspension forks don’t just absorb the impact, it tends to extend itself in order to maintain good traction. This means that you’ll have less initial sag when climbing. When descending, the fork will extend itself to maintain good traction and stability of the bike.

Sag is defined as the difference of air pressure between the front and the back of your bike when it is compressed. It’s measured in millimeters.

The sag should be set according to rider preference for your bike. If you’re riding downhill, then you can use your thumbs to set the sag, but if you are climbing a steep hill, the best way is to use a DIN (Do-It-Yourself) gauge. The traditional way is using a wheel spacer called an air bin. 

Rear Shock Sag Setup

For a rule of thumb, rear shock should be set to open mode. If you are using a coil-over shock, then please use the shock-centering device to achieve the correct rear sag. It is better to get a shock pump for your rear suspension. 

1. Initially, firmly bounce upward and downward. 

2. Once you’re seated comfortably, at least let the bike be settled for not less than 5 seconds. Ask your friend to push the O-ring and pedal to make sure there’s enough air pressure.

3. Check the sag by letting go of the O-ring and counting. 

4. Re-adjust again if needed until you have the correct rear sag. 

5. Confirm your ideal setting on your shock!

6. If you have a coil-over shock, then check if there is no coil binding after the initial bounce and full seated position from the rider on top of it. 

Fork Sag Setup

You can use fork bounce emulators for setting up your fork sag. You can adjust the O-ring in the forks for your bike to achieve your desired fork sag.

1. Place the truck of the bike to hang with a hook or wire bail, but don’t let it hang onto a large drop as it could damage your car or scratch it. 

2. Once you’re seated comfortably, at least let the bike be settled for not less than 5 seconds. Ask your friend to push the O-ring and pedal to make sure there’s enough air pressure.

3. Re-adjust again if needed until you have the correct fork sag. 

4. Confirm your ideal setting on your fork!

5. If you have a coil-over shock, then check if there is no coil binding after the initial bounce and full seated position from the rider on top of it. 

Optimize the Air Spring Rate

When we say spring rate, we’re referring to the amount of pressure that is applied to your suspension. The default spring rate on a new bike is 150 PSI. If you’re a beginner and new to mountain biking, then you might want to start with this rate value.

If you’re an experienced mountain biker who is riding a lot of rough terrains or jumping off big hills, then you may want to consider lowering the pressure as it will make your bike more sensitive to bumps while still maintaining adequate protection from bottoming out.

When your shock spring rate increases, the action of the suspension will be more intense and more resistant to shocks. This is beneficial for aggressive riders who want the maximum level of control on their suspension.

However, for people who are not too aggressive with their use of the bike, high spring rates can actually result in lesser performance.

Adjust the Spring Rate Progression

The best place to start adjusting your spring rate progression is on level ground. Start with a low pressure, then bump up the pressure incrementally until you feel the suspension braking and bottoming out, depending on how much you’re riding at that point.

The length of time the compression can go beyond the end of travel is called climbing or trail. 

When you have more climbing or trail, the rear end of the bike swings out to a greater degree when it hits an obstacle. 

This will help the rear wheel clear obstacles without bouncing in and out of contact with the ground. It is good for jumping and light downhill riding, but during harsh braking, it will cause a wag in the back-end of your bike.

Adjust the Compression Settings

Compression is the second step in fine-tuning your suspension settings. Compression is how firmly the suspension adjusts to bumps.

You’re looking for a bike that has well-balanced compression. In other words, you don’t want any parts to be too hard or too soft.

Bike manufacturers recommend you to set the compression at between 20 and 50% of the maximum recommended travel length (when set by the manufacturer). Compression works hand-in-hand with sag.

A good guideline is to set the compression at around 10 to 20% while setting the sag. Then, start adjusting it to your personal preference.

1. Loosen the compression lever by turning it counterclockwise and move the rebound lever into its middle position. 

2. Push down your seat post and this will put the bike in its fully compressed position when you’re riding downhill.

3. Measure the distance of travel using a tape measure.

4. Then, move the rebound lever to regain your natural position and adjust your compression to about 20% less than what you measured, so if your bike sags 7mm then set your compression to 5mm and so forth.

5. Make sure that both are in the same setting; rebound and compression should be matched. Check again after and repeat until it feels right for you. 

Manual compression is very simple but you need some experience to set the height accurately. Manual compression uses the rebound lever to adjust the compression. You can get it off by turning the rear axle of the bike outwards.

When you refer to “outward” this means camber, so if you turn it towards a steeper angle, then the wheel will ‘act’ stiffer than if turning it towards a shallower angle.

After adjusting, make sure that you keep your rebound in its middle position otherwise the suspension will become too soft or too hard.

Tune-Up the Rebound Damping

Rebound damping can smooth out the bumps when the suspension is working. 

On the other hand, too much rebound damping will not let your suspension move freely. This is because as the spring is compressed, it creates an elastic force that pushes back the wheel. Because of this, you can lose traction on slippery surfaces or have a wheelie when going down a hill. 

To tune it up, follow these steps:

1. Secure your shock and take it off. 

2. Place a shock pump on your side and attach it to a compressor using a hose. If you’re working on a fork with compression adjustment, then adjust it here too so that it’s close to you. 

3. Make sure you’re on a level surface and remove the air canister from your shock.

4. Pump it up with the pump until it’s just slightly too long and let it come back to its normal length. 

5. Check the length by taking your spring scale and placing it at the top of the shock where you want to be. If you want to check on the rebound damping, then pump your shock until it’s about 3 clicks down from full compression and let it go again to set in that position. 

6. Repeat this for rebound damping. 

7. Reinstall your shock and test ride a few times to see how the suspension feels.

Adjust your bump damping by loosening it and pushing it up or down when you have the fork fully compressed. Usually, you want to start with a little bit of adjustment then work from there to make sure that you are happy with the ride.

Set Low-Speed Compression Damping

Low-speed compression damping is the third adjustment you must make. This adjustment will let the bike absorb small bumps. 

Too much low-speed compression damping can cause the bike to roll over without absorbing the bump correctly. Too little low-speed compression can cause a bouncy ride and fork dive when cornering without absorbing the bumps correctly.

Adjust your rebound damping by loosening it and pushing it up or down when you have the fork fully compressed.

Low-speed compression is the suspension’s ability to absorb small bumps. It must be set correctly so you don’t destroy your suspension.

It can be adjusted using a rebound adjuster (if it has one) or by hand using a hex key and wrench. In either case, make sure that you do not touch the adjuster while adjusting because it will likely cause damage to your shock or forks.

Also, remember to not go much higher than 20% because this will destroy the springs of your shock.

If the bike bounces too much, then you want to lower the pressure by turning the knob counterclockwise. This will result in a softer spring rate and will result in more sag. If the bike is too stiff, then you want to increase the pressure by turning it clockwise.

This will give you a stiffer spring rate and a little bit less sag but not too much because that way may result in pinch flats or damage on other parts of your bike.

High-Speed Compression Damping

High-speed compression damping is the suspension’s ability to absorb large bumps.

Like low-speed compression, it is adjusted by turning the knob of your shock or fork. If the bike rides too smooth then raise it up, if it rides too hard then lower it down.

Essentially, when you change the high-speed compression, you change how harsh the bike is during braking and acceleration.

Adjust the Rear Damping

The rear damping is adjusted in a similar way to the front damping. The only difference is which knob controls how much high-speed compression damping it has.

For the rear, it’s controlled by turning the knobs on your shock or fork clockwise if you want more high-speed compression damping or counterclockwise if you want less.

Inspect the Balance

When you’ve made the necessary adjustments to your suspension, double-check the balance of the bike to make sure it’s not leaning to one side. If it is leaning, then you’ll need to pick up some weights and place them where they can even out the balance.

Rear Shock Leak Testing

Check if there’s a leak in your shock. If the oil is gone from the shock, then you’ll need to re-fill it with the right amount of oil. You should only do this if you have a shock pump, however. 

You can look up some tutorials on YouTube to learn how to use one.

Check your shock oil level from time to time just to ensure that it’s still at its appropriate level and never overfilled as it may cause damage to your shock or forks.

FAQs

What PSI should my mountain bike shocks be?

Check with your specific bike’s user manual for the correct PSI settings that are suitable to your weight and terrain. If you’re not sure how to correctly check this, then take it to a professional bike shop for them to do it.

How do I know if my mountain bike shocks are bad?

Cracks or leaks in your forks or forks with worn-out seals can be an indication of a bad shock. If you think that your shocks need to be replaced, then get them checked by a professional bike shop. Unfortunately, there’s no definitive way to tell if your shock needs to be replaced unless you take it to a professional. Worn-out shocks can make your ride feel harsh and bumpy.

How can I make my suspension softer?

The best way to make your suspension softer is to add more oil to your shock. If you don’t have access to a shock pump, then you can add small amounts of oil (around 2-4 tablespoons) until you feel that the suspension is at the right level.

If it’s leaking, then most likely it’s just air in your shock and not a leak, and adding a few tablespoons of oil should fix the problem.

How do you fix a front suspension on a mountain bike?

Check the recommended PSI from your mountain bike’s user manual, then pump your front forks until they’ve reached that level. If you’re not sure how to do this, better have a professional bike shop do it.

Final thoughts

Mountain biking can be fun and it is a great way to get your body to where it needs to go without quitting. Mountain biking can also be dangerous if you are not accountable.

Make sure that you have the right tools so that if anything happens, then you will be able to fix it right away.

You should always check your suspension before any big ride, swimming trip, or other activity to make sure that they are in good working order and in proper adjustment.