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how to set up your MTB suspension

7 best tips on how to set up your MTB suspension

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Whether you’re buying a brand new mountain bike or you find a great second-hand deal, there are a number of things you’ll need to take care of before you start riding.

Probably the most important one is how to set up your MTB suspension, which is the topic of this article.

Setting up your MTB suspension is rider specific and no matter how well the initial setup is done, knowing what to do yourself is a requirement for getting the most out of your suspension.

Besides personal experience, the following videos are a great way to learn more about how to set up your MTB suspension from Jordi Cortes, who’s the Global Race Department Manager of Fox and well-known face on the Dialed flogs.

I’ve taken the liberty to pull screenshots from those videos

#1 Ride with a well-serviced fork

I don’t have any numbers, but the number of mountain bikers who service their suspension based on manufacturer’s recommendations is extremely low.

And if you buy a second-hand bike, ask for the service history, expecting there to not be any, no matter how old the bike is.

I bought 3 second-hand mountain bikes with suspension, two were full-sus. Only the hardtail was said to be serviced recently and performed as you would expect for a serviced fork.

The other two were shot to pieces. Something I didn’t notice with a single test ride, which I performed on only one of the two bikes that had issues. My bad.

A fork that hasn’t been serviced or serviced well has issues when it’s been used for what it’s meant for. Low oil, no oil, worn shafts, worn bushings, worn everything, leaking seals, leaking oil, leaking air, leaking everything, no lockout, no compression, no rebound, no everything.

Everything that can break will break without service, and a broken suspension doesn’t function. So get it serviced, and get it repaired when needed.

#2 Use bracketing

Setting up your suspension is done with the help of a process called bracketing. Bracketing means you change one aspect of the suspension to a certain agreeable setting, before moving on to the next one.

You change a certain setting in such a way that you try to improve upon the overall performance of the suspension. If you achieve an improvement you move forward by changing the setting into the direction you were heading.

For instance, adding more rebound compression results in an improvement, you add even more rebound compression than that’s already there. This can either be 2 or 3 clicks or a certain amount of infinite, non-dedented adjustment.

If changing a setting does not result in an improvement, you move to a setting in between the previous and current setting.

If there is no such in between settings you move back to the last setting before the suspension’s performance deteriorates.

Writing your settings down before adjusting them is necessary to perform bracketing correctly.

#3 Setting air pressures (air spring adjustment)

Suspension needs an amount of rider specific air pressure. Each specific suspension, fork or shock, comes with an air pressure chart to determine the initial amount.

This initial amount is a general approach to setting air pressure, which needs to be further tuned. The amount of air pressure can differ for the same fork depending on your riding style, terrain, and bike geometry.

  • Too much air pressure will result in the suspension not compressing (enough), making for a less comfortable, bumpy ride, which feels harsh on the hands and body, with a heightened risk of losing control.
  • Too little air pressure will result in blowing too quickly through the amount of available travel, bottoming out the travel on harsh impacts, front-wheel diving, particularly when cornering, and an all around more exhaustive ride with less control.

Setting sag

The way to know for sure the amount of air pressure is correct is by setting sag.

Sag is the amount of travel used when you sit on your bike in your riding kit and accessories (hydration pack, snacks, tools, whatever) in your normal riding position.

The amount of sag depends on the amount of travel of your suspension, and should be around:

sag
light trail riding
aggressive, steep trail riding
shock
25%
30%
fork
15%
20%

Determining how much sag you have for your suspension is done by sitting on your bike and getting out of the saddle.

Make sure you perform this process on level ground and without holding the brakes. If you find it difficult to maintain control, and constantly fall off the bike, let somebody aid you.

While out of the saddle in a neutral position, push the sag o-ring down onto the fork seal for your front suspension and air sleeve seal for the shock.

Then lightly bob while out of the saddle to break through the initial stiction of the fork/shock.

The lower leg of your suspension will push the sag o-ring higher up the stanchion. The air sleeve will push it down. Dismount your bike without further moving the sag o-rings.

Calculating sag

You can then calculate the sag with the following formula:

sag = distance between o-ring and seal / amount of travel

  • If the amount of sag is too high remove a bit of air pressure
  • If the amount of sag is too low add a bit of air pressure

You’ll need a shock pump to add air pressure. After removing or adding air pressure, repeat the same process of setting sag until the result is satisfactory.

#4 Setting air volume (air spring adjustment)

Having a correct air pressure means the suspension provides the correct amount of impact support, but may still use the amount of travel ineffectively, either too little or too much.

This is based not on your static position on the bike, but the demands of the trail on the suspension.

  • A rocky and rooty trail with steep descents and possibly a number of small or large jumps, will ask for an amount of air volume where pressure builds up quicker to provide enough counter-pressure, making sure you don’t bottom out an/or blow through your travel too early.
  • A flowy trail without rock gardens and technical descents or jumps needs air volume where pressure builds up slower, so the suspension is allowed to travel even on lower impacts.

If the suspension allows for it, you can manipulate the air volume in your air spring with volume spacers, effectively reducing the amount when added.

Some suspension allows for up to 7 volume spacers, enabling the suspension to act more progressively, and more quickly ramp up towards a state of high pressure and more bottoming-out resistance.

Testing volume

Obviously you can ride a real trail to feel if you’re regularly bottoming out or sit too high in your travel.

However, a quick volume test will do the trick as well, and entails riding slowly on your bike on even ground and do a couple of quick bounces or bunny hops to mimic a large impact.

You should see 80 – 85% of travel being used this way to determine a proper air spring volume. Use your sag o-ring to gauge the amount of travel.

  • Too little travel means removing 1 or more volume spacers
  • Too much travel or bottoming out means adding 1 or more volume spacers

#5 Setting compression adjustment

Compressing is the amount of force necessary before the suspension starts to move into its travel.

If the suspension has compression adjustment other than “open” and “closed” settings you want to set it for the typical trail riding you do.

  • Almost all current suspension has low-speed compression, which is compression adjustment for the initial downstroke, low frequency movements, also called small-bump sensitivity. Examples of these are moving your body on the bike, braking, and minimizing trail chatter.
  • Some suspension, especially high-end trail, enduro, and downhill suspension, has high-speed compression as well. This is to finetune high-frequency brake bumps, square-edge hits, and drops.

Setting compression adjustment is the same for both high- and low-speed compression. The only difference is the ability to test it. For low-speed compression you’ll need a flowy trail, for high-speed compression you’ll need to find a trail that’s more demanding and will cause the travel to go towards or into the last quarter of its travel.

A good place to start is the middle of your adjustment. If you have 10 clicks of low-speed compression, pick 5, do a run, then change it two clicks, up or down, and do the same run.

Use the aforementioned bracketing process to get to the right amount of fine tuning.

#6 Setting rebound (damper adjustment)

Your suspension has rebound compression adjustment, which determines how fast the fork decompresses to get ready for the next impact. Rebound is the inverse of compression.

All suspension has rebound compression. Some premium suspension has both low- and high-speed compression.

  • The least amount of rebound compression means the fork returns the fastest.
  • The most amount of rebound compression means the rebound is compressed the most and it takes the fork the longest amount of time to return to its uncompressed state.
  • Rotating the rebound adjuster knob clockwise, usually located at the bottom of the lower leg housing the damper, slows rebound
  • Rotating it counterclockwise speeds up rebound (less rebound damping)
  • If rebound is too slow, consecutive impacts will eat through the available travel too quick, causing the front of the bike to dive and generally having less control. This also results in a harsh ride because the suspension sits at the last part of the spring curve, failing to soak up more impacts, instead translating them to your body through your hands.
  • A rebound which is too fast also mean less control. In this case because the rebound can cause the wheel to lose contact with the trail, making it feel jumpy and harsh. The suspension sits at its upper portion, also failing to soak up small and big bumps, causing even trail chatter to be felt.

Testing rebound

You can set both high- and low-speed rebound by the bracketing process mentioned at setting compression. However, you can do a quick rebound setup the following way.

You can check for the correct amount of rebound compression by placing the bike on level ground and either quickly pushing on the handlebars or saddle to consecutively check the front suspension and shock.

Ensure you use up about 50% of travel to activate both damp circuits that control high- and low-speed rebound compression.

Adjust the amount of rebound compression when the wheels move away from the ground or the suspension decompression feels overly sluggish. The first one is easiest to notice.

All settings including this one work together to create the smoothest possible ride.

#7 Rinse and repeat

  • Doing it once doesn’t mean your bike feels right on the mark with each ride. As your riding style progresses or you radically change the type of trail you ride, you might want to revisit this tutorial and go through the steps again.
  • Also, everything’s related to each other. As you add compression, you might feel you need to drop a little air pressure as well to remove the sting from your suspension.
  • Whatever you do, also start with the correct air pressure or sag before tinkering with your suspension settings. You cannot dial-in a correct suspension setup with an incorrect air pressure.
bio vanseijen

Johan van Seijen

FoundeR Restoration.bike

Johan van Seijen is the founder of restoration.bike. His passion for cycling in general, and restoring older bikes turned into a website to share his knowledge with a broader audience. Starting out on his father’s road bike and riding classics as the Amstel Gold Race and Liege Bastogne Liege he has shifted his attention to trail, XC, and gravel riding since. No matter how much he loves writing about everything related to cycling, nothing beats actually using his ever-expanding bicycle collection.

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