Suspension Basics

Your suspension moves up and down. Why? Because if you want to maximize grip and comfort, you want the suspension to move to keep the tires in touch with the road as efficiently as possible – too little suspension movement, and the bike will lose contact with the ground as it treats every bump as a ramp or a cliff, and too much suspension travel, and it’ll end up never reaching equilibrium, so the chassis swings around like a Caddilac with blown shocks, more bounce house than composed. The sweet spot is a “compliant” chassis – it moves with you, predictably, and consistently, so you’re not fighting it. In an ideal world, the suspension would perfectly track the road at all times, but it’s hard to get there cheaply, so we have suspension settings to help you find the right compromise for your use case.

How do you get to compliant chassis?

The first thing to do is to get your spring rates right and set sag – I’ll leave those out, as there are plenty of good resources on that around. Once you’ve got that baseline with sag and preload, we’ll talk about the interesting stuff – the clickers on your suspension, and what they control. There’s a couple of different types of suspension, but this will generally assume non-electronically controlled cartridge forks.

Front Compression

Compression damping controls the speed that your suspension compresses under a hit. If your suspension is in steady state, riding in the upper part of its stroke, you want it to handle weight transfer from braking or cornering loads progressively without huge amounts of dive (low speed compression damping). Ideally, this means when you apply the brakes, there’s a moment of transition where the suspension helps you load up the tire progressively, squishing it into the ground and building traction, allowing the rider to maintain control without sliding the front, or if they’re really hard on the brakes, without the rear tire lifting off the ground suddenly. Too little low speed compression damping and the suspension collapses under any load and you’re likely to bottom out. Too much low speed compression damping and the chassis doesn’t move under load, and the tire takes more load in transitions. This also can make the ride harsher.

But when you hit a big bump, you want the suspension to give a lot very suddenly, because otherwise you’ll dump all of that energy into the chassis, and upset the chassis with that sudden hit. That problem is managed by high speed compression damping – when you hit the front forks with enough force, the damping transitions from the low speed damping circuit to the high speed damping circuit, and moves much more quickly. This allows the suspension to move quickly when it contacts a large bump, avoiding the tire having to suddenly absorb that impact and maintain traction, and avoiding it suddenly causing all of the impact to transition into the chassis. Too much high speed compression damping and the front end doesn’t move when it hits a bump, just rides up them, making a very harsh ride, and too little high speed compression damping, and the suspension collapses too much when it hits a big bump and bottoms out, creating a harsh ride when you bounce off the bump stop. The target, again, is a compliant chassis in that sweet spot. Front suspension usually doesn’t allow independent adjustment of high and low speed compression damping.

Front Rebound

Rebound damping controls how quickly the suspension extends after it is compressed. More rebound damping means the extension takes place slower, less rebound damping means the extension takes place faster.

Rebound generally doesn’t have high speed and low speed controls – however, the goal is the same: keep the tire in contact with the ground. Rebound damping maintains a compliant suspension by making sure that as you hit a bump and the suspension absorbs that energy, the forks release that energy in a controlled way. Otherwise, you hit a sharp bump and the suspension moves smoothly with to absorb it, and then immediately unleashes all that stored energy and upsets the chassis when it springs back to where it was before. So rebound damping slows that transition and helps you manage, well, rebound. Too much rebound damping means the suspension “packs in” as it hits progressive bumps and never returns to equilibrium ride height, leading to bottoming. It can also lead to the wheel floating off the top of bumps as the rebound keeps the tire from following the road. Too little rebound damping, and bike will hit a bump and then continue to bounce up and down for a long time as the springs slowly lose energy to friction.

Rear Suspension

Rear suspension has similar settings to front suspension – preload, rebound. However, nice shocks will generally have high and low speed compression damping adjustments, allowing you to better control how the bike handles weight transfer and bumps.

Shocks are usually described as “1 way, 2 way, or 3 way adjustable”, depending on design. The additional adjustability is nice if you can afford it, as the cost of changing the shim stack to to a more appropriate setting if you don’t like how one of them is set is usually more expensive than just buying the nicer shock. Most shock companies will get it right out of the box, as long as they’ve done enough kits to get a good setup for a given bike and use case.

Ride Height

Ride height is adjusted by moving your forks up or down in the triples, and either making your shock longer or shorter, or adjusting a ride height rod. In general, if you lower the front end of the bike or raise the rear end of the bike, you will remove trail from the front end, and the bike will turn more easily but lose some stability. If you raise the front end of the bike (forks lower in the triples), or lower the back end of the bike, it will “chopper out”, and become more stable but harder to steer. Too much in either direction will generally lead different forms of instability. Too much trail and the bike will continually hunt and weave as it self corrects too much and overshoots center, too little trail and the bike will become unstable because it doesn’t have sufficient self-correcting force to response to changes in direction. Much like fighter jets, this instability can be agility, but it can also lead to tank slappers. Rider beware.

Ride height is generally best set early on, because it also impacts weight distribution. A little goes a long ways – it’s common that a good rider on a bike they know will easily notice adjustments in the 2mm range. It can also be useful to use ride height to compliment tire profile and choice – a more triangulated tire might respond well to a more stable setup, whereas a more rounded, softer tire might still be very good with a more aggressive setup. A thing to remember is that while you can always push the bars harder to turn faster, it’s difficult to add stability via your inputs once it becomes unstable.

Tuning for you

The most important thing about all of this is that you’re happy with the suspension. Setup is a pretty personal and individual thing. Start with getting your spring rates, preload, and sag right. Your suspension should come with a baseline setting, start there. If you move a few clicks, and don’t feel anything, move a few more clicks. It’s almost impossible to get a dangerous setup (outside of major ride height adjustments) on a modern set of suspension, so you should feel free to use all the range.

Some Notes:

Do not hard bottom the compression / rebound, you’ll break stuff – they should have clicks or turns, do not torque them hard at full soft or full hard – finger pressure only. Preload will require a wrench / socket, as you’re physically compressing the spring.

Record your setups so you can get back to a known good setup.

You want the softest setup you can get away with without bottoming or excessive weight transfer – the stiffer the setup, the more you demand of the tires. Let the suspension do the work and more traction is available for braking, turning, and accelerating. Start from full soft and stiffen things up from there.

Settings are always recorded from a fully bottomed adjuster, which sets it to maximum damping. “5 clicks” is “5 clicks out from all the way in”.