Modern mountain bike suspension components have come a long way. The latest crop of suspension forks for XC, trail and downhill bikes make use of lightweight materials and advanced suspension engineering to deliver performance that meets the demands of various disciplines of mountain biking, and allow riders of all abilities to customize suspension performance to their riding style and local terrain.
That said, the downside of the incredible level of customizability offered by modern mountain bike suspension components is the dizzying array of adjustments, which - for the average rider -can be very confusing. Suspension forks and shocks come with various valves, knobs and levers to adjust everything from air springs to compression and rebound settings.
There are certainly seasoned riders who seek out and benefit from the nitty-gritty of suspension adjustments, and tweak their settings to match various types of terrain and riding scenarios, and that’s where a comprehensive understanding of all the different settings as well as suspension theory really helps. Nevertheless, the majority of riders want to “set and forget” their suspension for optimal performance for their riding.
In this article we present a guide to the fundamentals of mountain bike suspension setup.
Spring: the spring is the part of your fork or shock that progressively becomes stiffer as compression forces are applied (when you, say, hit a bump with your wheels or land a jump or a drop). The spring can be made of metal, like a coil spring, or a compressed gas, like what you’ll find on air forks and shocks.
Damper: The damper is what provides control over how the spring behaves. Without a damper, your suspension is just a pogo stick, and you will bounce around with little control all over the trail. There are two types of damping: compression and rebound.
Compression damping: This type of damping controls the force that moves a spring across its range of travel. This is done by means of a suspension fluid which is compressed through a system of ports and shims known as the compression circuit. Suspension engineers design the specific arrangement of those ports and shims for certain suspension characteristics, as well as allow a user-customizable range of adjustment using levers that control how the compression circuit operates. On most forks, compression damping will be controllable using a knob, dial or lock-out lever (or a combination of those things)
Rebound damping: this refers to the part of the fork/shock that regulates how the spring returns to its original state (i.e. full travel) after compression due to an impact force applied to it. Similar to compression, rebound damping works via a rebound damping circuit which regulates suspension fluid flow, which in turn controls the speed with which your suspension rebounds, or extends, back to full travel. You will often find rebound damping adjustment using a knob or a dial located on the bottom of fork legs or below the compression damping lever on rear shocks (refer to your suspension manual for accurate manufacturer information)
Sag: sag is the amount of suspension travel that is compressed under static rider weight. Setting correct sag is vital for optimal performance of your suspension. Sag is also known as suspension preload.
Read on for how to get your suspension baseline dialed in…
How to set up your suspension baseline
Step 1: Set your sag
For this step you need to be in your full riding gear, including helmet and shoes and a hydration pack (if you use one) full of your usual amount of water, which will ensure that you set sag correctly at your fully geared up weight. Your fork/shock stanchions should have their suspension travel O-rings (if they don’t, you can use zip-ties)
Make sure your fork and shock are in the open mode and the suspension travel O-rings are seated against the wiper seals.
Have a friend assist you (or lean against a wall for support) and mount the bike in the neutral riding position. Allow the bike to settle into its suspension.
Carefully dismount the bike without bouncing and measure the distance the o-ring has moved away from the wiper seal (in mm). Let’s call this measurement X
Percentage sag= X/stroke length*100
To adjust sag to a certain percentage, add or remove air pressure from your air chamber and repeat the above steps.
Your bike’s manufacturer will have a recommended sag setting. If not, you can start with a baseline setting of 20% for your fork, or 25%-30% for your shock. This is your suspension sag baseline.
Step 2: Fine-tuning your suspension spring rate
Set your compression and rebound adjusters to their midpoint on the available adjustment range
Go for a short ride on a trail you are very familiar with and take along a shock pump. Note how the suspension behaves.
Make adjustments based on how your suspension is reacting to forces applied to it by impacts on the trail as follows:
If you are using too much travel or bottoming out easily on small to medium hits: reduce sag (add air pressure in 5-10 psi increments)
If the bike feels harsh and bounces off obstacles at high speed and doesn’t offer good traction: increase sag (reduce air pressure in 5-10 psi increments)
You will want your fork/shock to feel reactive under small bumps and only use close to full travel on big hits (jumps or drops)
After arriving at air pressures you’re happy with, make sure you make a note of those pressures.
Step 3: Fine tuning air spring damping:
If the fork has good ground tracking and traction, but dives on hard braking or on steep descents: add two to three clicks of compression damping
If you are struggling to achieve full travel on big hits, remove compression damping
Step 4: Fine tuning rebound damping:
If your suspension feels too bouncy, bucking you hard after big impacts: add two to three clicks of rebound damping ((turn rebound knob towards the + icon)
If suspension doesn’t recover quick enough after successive hits on rough trails: reduce rebound damping (turn rebound knob towards the - icon)
Suspension setup is a dynamic process, and is very rider-specific. There are several variables, including your riding weight (fully geared up), type of terrain and trails you are riding, different
suspension components, etc. Experimenting with different settings and adjustments is key to getting the most out of your suspension. What works for an elite racer on the Enduro World Series isn’t necessarily what will be an optimal setup for you, even if you ride an identical bike!
Make small adjustments to one thing at a time so that you’d be able to know which changes resulted in changes in specific handling characteristics. Record your settings (using pen and paper or the notetaking app on your phone)! When it is time to service your suspension components, it will make life much easier to get your bike dialed in once more.
Use the above guide to understand the basics of suspension setup. There is a lot more to suspension setup than what we covered in this article, but this guide is meant to give you the fundamental – and very important – baseline for suspension settings that would allow you to further tinker, tweak and fine tune to arrive at your perfect setup.