Friday, January 28, 2022

How to Adjust Mountain Bike Shocks?

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Shock absorbers are a significant part of mountain bikes. Without them, the bike will be rigid, and it will be highly uncomfortable for a person to ride on a bike with no suspension or faulted Suspension.

Fortunately, you can adjust mountain bike suspension on your own, but this feature is only in air suspension bikes. Bikes with spring suspension cannot be adjusted. You have to change your suspension spring coil if you want to adjust in spring suspension.

shock absorber mountain bike
Source: By daniiD/ Shutterstock

Are all-mountain bike shocks adjustable?

Most of the bikes now a day have air suspension, which is fully adjustable. Here we are going to elaborate on the steps to adjust mountain bike suspension

Usually, mountain bike suspensions are adjustable in three ways:

  • Adjust Mountain Bike Sag
  • Adjust Rebound Rate
  • Adjust Compression Setting
  1. Adjust Mountain Bike Sag

Sag is the suspension amount you use when you sit on the bike. In other words, the volume of the shock absorbed, pressed by your weight is called Suspension Sag. We want the sag because the wheels can adapt to the roughness while riding on rough ground.

How do I Set my Mountain Bike Sag?

It is essential to set the right level of sag in suspension.

Rear shocks – it should be 25 – 30%. If the suspension sag is lower, it will not absorb bumps by slightly big rocks & bumps. You may need more or less sag according to your weight, bike & riding style

Front fork– 10% sag is enough because the front forks don’thave to bear much of our body weight.

When weighed, the suspension can come down too much. With too much sag, the suspension gets too much pressure in its journey. With a considerable reduction, you will not get maximum suspension performance.

How to measure the sag in the bike? Nowadays, most mountain bikes have a chart for rear shocks & front fork legs so you can easily adjust the sag.

But if there is no chart, you have to eject all Air in shocks and press the shock to its complete end & mark its total capacity – measure the starting & ending point of shock using a measuring tape.

After that, fill the Air in shocks & tilt the pedals and find a neutral riding position. Next, reach down and slide the O-ring completely against the dust wiper. Then slowly lower the bike without further pressure. As you unload your bike, the ring will indicate how many strokes you have used.

Measure the length from the dust wiper (starting point )to the O ring level. Now apply the formula below.

% Sag = (Stroke Used) / (Total Stroke Length) * (100 %)

After getting the sag percentage, add or remove air pressure according to the required amount (25%) using a shock pump and adjust the sag at optimal rate.

2. Adjust Rebound Rate

The speed of the rebound rate is adjusted by suspension damping.

Damping is fluid(air or oil) in shock absorbers & forks that goes through a series of chambers when press by Piston. Fluid moves more slowly through small chambers than through large ones. When adjusting the knob of the dumbing, we are actually changing its hole size from which it passes through multiple chambers.

What is rebound on a bike?

Rebound damping controls the speed of the Suspension’s uncompressed state after a shock. Generally, the rebound rate should be minimal. Mostly shock absorbers have a rebound damping knob,

Too much rebound will cause your Suspension to pack down, resulting in a harsh ride.

A higher rebound rate can cause higher bouncing & trampoline effect, while a lower rebound rate causes can pack up your suspension. Your aim should be to maintain a minimal trampoline effect with a a higher rebound rate.

In many shocks, the rebound adjusters are dial adjusters under the hook leg. Adjusters are located on the back of the jolt in some places (some are easier than others), and if you can’t find it quickly, you’ll want to refer to the documents on your jerk. Turning the rebound knob clockwise will increase the speed the fork recompresses, and turning it counter-clockwise will reduce the speed.

To start, rotate the knee in one direction and then count how many clicks it takes to turn it entirely to the other side. This is your rebound range.

If you don’t have a good manufacturer’s recommended starting point, turn the knob toward the middle of its range (if you have 20 clicks if you have 10 clicks from either end) as you With the rebound setting, your ultimate goal is to have the rear suspension of the bike evenly spaced and at a rate that suits you. Light riders with low fluid pressure often prefer to recover faster than heavy riders.

Adjust Compression Setting

Most new mountain bikes have compression damping in the front suspension and rear shocks. You can adjust the knob clockwise (high air pressure) & counter-clockwise (low air pressure). High air pressure means your suspension will behave rigidly against rocks & not absorb many shocks, while Low Air pressure means your suspension will become too soft & jumpy that riding becomes difficult.

So you have to maintain the right amount of air pressure in suspension, which is neither too soft nor too hard.

If your bike doesn’t have a knob on the top of the front suspension fork, but your bike has air suspension systems, then don’t worry. You need a shock pump to adjust the pressure in the fork.

How do you set compression damping?

Just plug the shock pump in the top of the fork & adjust the pressure in it using the manual guide recommended.

Compression modes:

Many mountain bikes have a built-in Compression setting mode system. You just have to move the knob to adjust the setting:

Low-speed compression

Basically, low-speed compression affects how the Suspension compresses at low speeds and during low amplitude forces.

Don’t worry about losing negligible bump absorption too much; your tires are there for soaking up the small stuff.

Try to keep your low-speed compression damping settings balanced. For example, if you run very high low-speed compression on the fork and none on the rear shock, the bike will tend to shift more weight to the rear wheel during riding, and vice versa. A balanced setup is key.

Keep the compression setting on the front fork and rear shocks same, otherwise your bike will shift more weight on suspension where low speed compression is less.

Low-speed compression settings adjust the Suspension compresses at low speed & low stroke forces. Increasing low-speed compression will decrease the sensitivity of compression. Adding too much compression makes suspension extremely sensitive & your bike tires with a bubble on even small bumps & rocks. Keep your compression speed at a normal level. To do this you have to follow these steps:

First, move to knob to 0(zero), no low-speed compression, your bike will be rigid on slightly rough terrains.

Now move the knob (add few clicks of compression) & check it on trail. If you feel it’s suitable and your feet feel stable, stop adding more compression.

High-speed damping adjustments

High-speed compression is something for serious and professional riders and setting high-speed damping is something of a dark art. Most riders dial off the high-speed compression. They also dial in a few clicks of a high-speed rebound if they’re riding terrain with many jumps and drop-offs.

Adding high-speed compression is for using less suspension travel on high-impact forces. if you are rough & tough riding & have to pass through really rough terrain in which there is risk suspension bottom out then add few clicks of high-speed compression, it recommended adding high-speed rebound also if you add high-speed compression.

At full high-speed compression, your bike will become rigid on high-impact strokes. It will make your bike shock harder on high-speed impact so it is not recommended to add high-speed compression.

We’re not going to go into adjusting high-speed damping in this guide. If you have a shock with high-speed damping adjustment, your best bet is to refer to the manufacturer’s instruction manual and/or website.

Trail for hit & trial

Adjusting mountain bike shocks is relay on hit and trial. You need patience and focus. Your bike will not adjust on the first attempt so always find a trail where you adjust the suspension. After each adjustment check the bike on the trail by riding for meters, evaluate the suspension and then adjust again.

Adjust, evaluate & repeat until you get the adjustment comfortable for you.


How do I fill my mountain bike with air shocks?

Use a shock pump to fill Air in air shocks, attach the shock pump with air suspension nozzle & fill the air according to your requirements, you cannot and other pumps tire filling pump or standing pump for air shocks. shock pumps are available in online stores for around 40-50$

Are all-mountain bike shocks adjustable?

Air suspension mountain bikes shocks are fully adjustable while spring coil suspensions are not adjustable. They have to be replaced.

What PSI should my mountain bike shocks be?

Every mountain bike has a different shocks absorber & their size is different so recommended PSI of every shock absorber is different, but it lies between 100-200 psi, maintains sag level 25% & reduces PSI level according to it.

Is it wrong to bottom out suspension MTB?

Yes, a low level of sag causes MTB suspension to bottom out, which causes further damage to the bicycle frame and rim. Your bike will be balanced out in this case. Keep the slag around 25-30%.

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