Shock Value: Suspension Setup Guide

Our Shock Value series continues with a thoughtful explainer on suspension setup. Although we specifically wrote this for those of you who may be new to suspension, it also builds up to some pretty deep subjects. Even if you can recite all your settings by heart, reading through this could still be a useful thought exercise…

Shock Value is presented by RockShox

They say that cooking is an art and baking is a science. Setting up your suspension is somewhere in between. There is a lot of room for interpretation, but there are also some established rules that you can trust will get good results.

Before we dive into those rules, we recommend you have our Shock Value Glossary at the ready. There will be some jargon incoming. But the principles are pretty intuitive. When we talk about “setting up” your suspension, we’re simply talking about making its suspension plush, but not too plush. Making it react quickly, but not too quickly.

Suspension setup is how you tune your bike’s behavior to suit your body, your terrain, and your riding style.

Because this is a long one and you might want to return to it for a specific tutorial, we’ve indexed it for you…

Index:

Tools Required

There aren’t many special tools required for suspension setup. The most important one is a shock pump, which is a small-volume, high-pressure pump designed specifically to work with air suspension. The second most important tool is a metric ruler, tape measure, or caliper. The third most important is a willing friend with fifteen minutes to spare, but you can get by without them.

If you’re looking to install volume spacers in your suspension, there are special tools and equipment required. The same goes if you need to set up a coil-sprung bike. But we’ll cover volume spacers and coil springs later.

Manufacturer Recommendations

You may be able to take your first step towards learning your proper settings without even pulling your bike off the hook. Many fork and frame manufacturers provide guidelines for certain settings based on your weight. Although these are just general suggestions, and will not be right for every rider in every situation, they’re the perfect place to start when you’re getting to know a bike.

Whenever following these guidelines, always include whatever you’ll be wearing on a ride in your body weight. Stuff like your pack and all of its normal contents. This will help get you the accurate range for air pressure, and when offered, the right number of clicks of rebound damping. Also, and this applies to every adjustment we’ll cover, you’ll get best results if your suspension components have been recently serviced or are nearly new. Any friction or contamination will throw off your results.

Some forks will have a sticker right there on one of the legs to guide you. The rear shock is more complicated because its proper settings will depend on your bike’s make and model. That’s why some bike brands will have a guide on their website.

RockShox Trailhead App

If you own a RockShox fork or rear shock, their TrailHead app can tell you your baseline settings from just a serial number and a few simple facts about you and/or your bike. Quick note on those baseline settings. We’ll discuss this below when we cover damping, but some current-generation high-end RockShox dampers have a “middle” starting point, while others start from “closed.” If your knobs have printed lines, and one of which matches up with a notch on the fork or shock body itself, that’s the starting point. But TrailHead goes beyond just knobs and clicks. It’s also a good source for education about your particular suspension components’ features, service requirements, and maintenance tutorials.

The TrailHead app also has a “Journal” feature that allows you to keep track of what your settings were on a given ride, mark that ride’s location on a map, and rate how well those settings turned out. It’s a good way to be methodical and patient about finding the right suspension setup.

This is a journey, not a destination.

Suspension Sag

Sag is how far your suspension compresses under your static weight, usually expressed as a percentage of total travel. On air-sprung suspension, you control your sag by adjusting air pressure, known as “preload.” Again, if your fork brand, bike brand, or better yet, your local shop has a sag or pressure recommendation for you, that’s the best place to start.

If not, it’s usually somewhere between 15% and 25% for front suspension, and between 25% and 35% for rear suspension. More aggressive riders may want slightly less sag, meaning a firmer feel. More casual riders may want slightly more sag, meaning a softer feel.

Riders who want to optimize for downhill terrain may want less front sag and — if they’re on a full-suspension bike — more rear sag. Riders who want to optimize for flat or rapidly undulating terrain may want their front and rear sag settings to be more balanced. Again, we’re cooking, not baking. You will be seasoning your suspension to suit your taste.

As you work on finding where preferences end up, we recommend that you occasionally try going well outside of the settings that initially feel “right.” Learn what it feels like when your suspension is obviously too soft or obviously too hard. This will help set up a framework that you will eventually narrow down to find your perfect settings.

It’s a tactic that becomes even more helpful when you get into the more nuanced dimensions of suspension adjustment like damping and air volume. But before you know where you’re going, you gotta know where you are, which means measuring your sag.

Measuring Your Current Sag

This is where it’ll help to have that friend nearby. You’ll need to be able to keep both hands and feet on your bars and pedals, and calmly rest all your weight on them for several seconds. If you try to get “in position” for only an instant, that will usually give you inaccurate results because your weight won’t be truly static.

Before you start, make sure that no lockouts are engaged. And if you have compression-damping adjusters, you’ll get best results if they’re all the way in their “open” settings. Also, locate the small free-floating rubber O-ring on your fork or shock. Over time, these sometimes rot and fall off, in which case, you can use a small, semi-loose-fitting plastic zip tie as pictured above.

Finally, it will help to know your fork’s exact travel and your rear shock’s stroke length. Just measuring the exposed stanchion length may not give you the correct number, so check your bike’s specs to be sure. Fork length should be easy to find if you don’t know it already, while rear-shock stroke length may be buried in your bike’s component details on the brand’s website.

Find a level, flat surface and have your partner stand in front of the bike with their hands on your bars. The next step may take a few tries and a little communication, but if you can climb aboard your bike without a lot of lateral motion, it shouldn’t take much effort for your helper to hold you up.

Regardless of whether you’re on a front-suspension gravel bike or a full-suspension mountain bike, you want to measure sag while in a standing position, centered over the bike as if you’re about to drop down a curb or navigate a bumpy section of trail.

Make sure you’re not pulling either brake. Give the bike a few bounces until it feels like the bike has reached an equilibrium in your neutral position.

Measuring Your Front Sag

Have your helper slide the O-ring all the way down until it sits flush against the fork’s rubber dust wiper. Then, gently shift your weight back onto the saddle and off the handlebars before dismounting so as not to compress the fork any further. The space remaining below the O-ring is your current front-suspension sag.

Measuring Your Rear Sag

Returning to the same position as you were in while setting your front sag, give another few bounces until you’ve found that equilibrium. This is more tricky than it was on the fork, but your helper should be able to reach through your arms or alongside the bike and slide your rear shock’s O-ring against the shock’s dust wiper. Your job, also tricky, is to then carefully lean forward onto your bars while unweighting your feet and gently stepping off the bike. Again, the space left by the O-ring is your current rear-suspension sag.

Measuring Sag Without a Helper

Once you’ve gone through the process with an assistant, you’ll know what to look out for if you have to do it by yourself. A common method is to use a wall that you can get close enough to for your shoulder or elbow to rest against. The trick is to avoid compressing the fork or shock further when you reach down to slide their O-rings, but there’s usually some “stiction” that resists motion when your suspension is at rest, so if you move slowly enough, this is a totally viable way to measure your sag.

Adjusting Your Air Pressure

So, now you know where you are, there are a few things to remember to get where you want to go. If you need to remove pressure, it’s best to do it slowly. Your shock pump should have a “bleed button” that does the job nicely. Adding air is simple enough, but there’s still a trick to it. Whether you’re increasing or decreasing pressure in your suspension, there’s an important step that’s often overlooked.

Most modern forks and shocks have a “negative” air spring, which actually works counter to the main “positive” air spring.

Negative air springs help decrease the force required to compress your suspension when you hit a bump. Nowadays, negative air-spring pressure doesn’t need adjusting because, whenever you compress your suspension a few centimeters, a hidden internal port equalizes its pressure with the positive air spring.

But that means that whenever you want to increase or decrease your preload, you need to “cycle” the fork or shock a few times. Listen carefully, and you may even hear a brief “psst” when pressure equalizes. As you’re changing pressure, just stop pumping occasionally before removing the pump and compress your suspension three or four times to achieve equalization.

Then, go through the sag-check process again until you reach the percentage you’re after. And for your first few rides after setup, bring your shock pump with you so you can adjust if you need to. Also, stop and reset that O-ring once in a while, and then stop again to check where it’s ending up.

If you find it bottoming-out in circumstances that weren’t particularly intense, maybe add some pressure. And if it’s never bottoming out, maybe remove some pressure.

This is a tricky issue, though. Some trails simply won’t demand all of your travel, so it’s best to try to put your bike in over its head before deciding to increase pressure. And yet, if you set up your suspension to never bottom out, you’ll often be leaving travel on the table and you won’t be taking full advantage of your suspension.

To put it very simply, your suspension probably should bottom out if you pick a particularly bad line or experience some other sort of unexpected, intense impact. Thankfully, you have some control over bottom-out behavior independent of your preload, which we’ll cover when we get to volume adjustment.

Once you know the parameters, setting pressure can be an intuitive, quantifiable process whose results are immediately noticeable. That’s true to some extent of the next step; setting your rebound damping. But we’ll be talking more about our feelings this time, so get ready.

Damper Basics

Suspension dampers control the speed of your suspension’s compression and rebound. When your fork or shock moves, it pushes a piston through an oil-filled chamber. That piston has a series of valves of various sizes and designs. When you adjust your damping, you are adjusting those valves, which control shaft speed. “More,” or “heavier,” or “slower” damping means the damper is doing more to slow down shaft speed, while “less,” or “lighter,” or “faster” damping means it is doing less to slow down shaft speed.

Setting Your Rebound Damping

Rebound damping and suspension preload go hand-in-hand. Rebound is acting opposite the force of your suspension’s spring. As you decrease preload, you generally need to decrease your rebound damping to allow your suspension to return to full travel and not get bogged down or feel sluggish.

And as you increase preload, you need to increase your rebound damping to keep that stronger preload from bouncing you back uncontrollably.

On suspension forks, rebound is usually controlled by a red knob at the bottom of one of the legs. On a rear shock, that knob might be in any number of places, and may even require a hex wrench to adjust. In the vast majority of forks or shocks, there is only one rebound adjuster, which controls “low-speed” rebound damping. We’ll talk about independent low-speed and high-speed rebound damping adjustment later.

Rebound settings are usually measured in “clicks” because most knobs will have a number of audible clicks as you turn them. If you know your manufacturer’s recommended setting, you’ll find it by counting clicks from the rebound’s fully “closed” setting. We’ll say that again because you might think it’d make sense for a brand to have you start fully “open” and count from there, but recommending clicks from “closed” gets more reliable results. If you don’t have a recommended number of clicks, you’ll need to trust your feelings. And that can be fun.

When adjusting rebound damping, our aforementioned suggestion of briefly trying out the “wrong” settings is especially helpful. Try slowing down the rebound all the way. You should notice immediately that your fork or shock is returning very slowly. And if you go the other way, you’ll get a bit of a pogo-stick effect.

Your correct setting is, of course, somewhere in-between. If you set your rebound too slow, you should notice the bike sitting too low because, after hitting a bump, it can not return to full travel quickly enough. It also may feel sluggish as you try to unweight the front or rear wheel to maneuver over or around an obstacle. Set it up too fast, and your bike may have a distracting “bounce” as you pedal or shift your weight.

There’s no right answer for exactly where you should land between these extremes. Slower rebound may help your bike feel more calm and stable, while faster rebound may help it feel more responsive and lively. Play around with it until you find what works for you.

Setting Your Compression Damping

Not all forks or shocks will have externally adjustable compression damping. Although there’s almost always a compression-damping system in there, you might not be able to change how it feels. The good news is, while adjustable rebound damping is a true necessity, adjustable compression damping is more of a luxury. You already have significant control over how supportive your suspension is via preload adjustment. Compression damping is essentially just another dimension of that support.

On a rear shock, compression damping is usually controlled by a black or blue knob and on rare occasions, may require a hex wrench. On a suspension fork, the knob is usually at the top of one of the legs. Sometimes that knob doubles as a fork lockout, where the damping gradually increases until the fork is effectively locked out. But don’t think about compression damping like a lockout.

It’s a way to control how your suspension compresses depending on the type of forces it’s under. As with rebound damping, if you only have one compression-damping adjustment, it’s for low-speed compression damping. We’ll cover high-speed adjustment later.

Generally, heavier riders tend to want more compression damping, while lighter riders will want less. But it’s hard for suspension manufacturers to suggest specific settings because personal preference also plays a big role. As you might expect, low-speed compression damping deals with low-speed compression forces. That includes pedaling or leaning or pumping. Unrelated to their body weight, riders who want to maximize support while putting this type of slow but forceful input into their bikes may want heavier compression damping.

On the flipside, riders who want to maximize the sensitivity and plushness of their suspension may want lighter compression damping. Just like rebound damping, we recommend riding with your compression damping set up on both extreme ends and paying attention to the pros and cons. There may be trade-offs to consider. That’s why suspension with independent high- and low-speed compression damping may mean fewer trade-offs.

Setting your High-Speed Compression Damping

Most decent fork and shock dampers are valved to react differently to high- and low-speed compression forces. But some high-end models may allow you to adjust for each independently. In these cases, the low-speed adjustment works as explained above. But the high-speed adjustment does something different. It controls shaft speed during sudden impacts.

Common sense might say that you would want your suspension to react as quickly as possible in a sudden impact, but more aggressive riders may find their suspension gets overwhelmed unless there’s something to reign that motion in. This is difficult to “feel” because even a really forceful push on the bars or pedals may not be enough to engage the high-speed damping circuit. You really need to get out there and start hitting stuff.

The goal is to keep your bike from giving up its travel in the moments you need it most. We recommend finding a very bumpy high-speed section of trail you know well, and run it a few times in various high-speed compression settings. Assuming you’ve got your preload dialed, you’ll know your fork’s high-speed compression is too fast if, although the first couple bumps are nice and supple, you find your front end dives easily and your steering stays tight and squirrely until you’re out of the chunk. Or it’s too fast in the shock if you sense you’re risking pedal strikes when pushing your rear wheel through things.

And you’ll know each are too slow if you’re staying plenty high in the travel, but you’re sensing a lot of feedback on initial impacts. Also keep in mind that there is often some cross-talk between high- and low-speed settings, where firm low-speed damping may stiffen your high-speed damping, though modern dampers are getting pretty good at minimizing this.

Setting Your High-Speed Rebound Damping

As with compression damping, many quality forks and shocks can react differently to high- and low-speed rebound forces. That can allow them to extend to full travel quickly after small, high-frequency impacts, while not extending too quickly after large impacts.

But the ability to adjust independently for each is a rare feature, so we’ll keep it brief. It’s best to think of high-speed rebound damping more like large-impact rebound damping. It comes into play when a fork or shock is returning from the very end of its travel, where spring force is greatest and shaft speed is highest. High-speed rebound damping is possibly the hardest setting to evaluate.

Pay close attention to the sensation of recovering from impacts that eat up most or all of your travel. If you find yourself getting bounced off-line every time you bottom out your suspension, you may want to slow down your high-speed rebound. But if you find large impacts tend to be followed by abusive chatter, you may want to speed it up.

If you can’t feel either, there’s no shame in just leaving it in the middle.

Adjusting Your Air Spring Volume

Now we’re really getting into the feels. Most modern forks and shocks allow you to adjust their air spring’s internal volume by inserting small specialized spacers. This doesn’t shorten your travel, but it does make your suspension more resistant to bottom-out, and may open the door to new approaches to other settings.

When you reduce the volume of an air spring, the internal pressure will increase more rapidly at the end of the stroke, increasing its resistance to compression. Volume spacers have become a very common tool for bike manufacturers to tune how a given model’s suspension feels.

It’s very likely that the air spring(s) on your current bike already have volume reducers installed right out of the box. That means you may be able to decrease or increase your air-spring volume to suit your needs.

We covered volume spacers in another post, so we recommend checking that out for a deeper dive. And the process of adjusting your volume will vary by suspension make and model. Some spring volumes can even be adjusted with the turn of a screw. So, we recommend also that you have your owner’s manual and/or an instruction video handy before starting this process. And of course, you’ll need the specific volume spacers meant for your fork or shock. Some new bikes may come with a few extra, but if you have to purchase a set, they’re usually less than $25.

We already mentioned that unexpected bottom-outs can still happen, even on properly set-up suspension. But if you are happy with the support and bump sensitivity your current settings offer, but those occasional bottom-outs are too harsh or too frequent, try increasing the number or size of volume spacers in your fork or shock.

Or, maybe you have the opposite experience. The bike still feels great, but even high-intensity impacts are leaving you with lots of unused travel. In that case, check if you could remove a volume spacer or replace it with a smaller one. In each case, you may need to rethink your pressure and even damping settings, so always keep an open mind.

Adjusting Coil-Sprung Suspension

Coil-sprung front suspension is extremely rare these days. It’s often seen in nerdy aftermarket conversion kits, used by savvy riders who wouldn’t dare click on a suspension-setup tutorial. But coil-sprung rear suspension is increasingly common. It can offer better bump sensitivity at the cost of extra weight and, unfortunately, at the cost of a more cumbersome adjustment process.

Although the threaded ring that captures the coil is technically a preload adjustment, it is only intended to make very small changes. Compress it more than two full turns, and the suspension won’t work as intended. To suit a wide variety of rider weights and preferences, coil shocks usually need the coil itself to be replaced with the one designed for you.

Because there’s no easily accessible O-ring to measure sag on a coil shock, it’s especially helpful to have someone nearby to assist you. The process is fundamentally similar to the sag setup outlined above, but someone will need to carefully measure the distance between the shock’s mounting bolts when you’re on the bike and when you’re off the bike. Just remember to divide that distance by the shock’s stroke length, not its overall length.

Speaking of length, not all coils are the same. They have to be meant for your shock’s stroke length, and you rarely can mix and match brands. If you need a different coil for a brand-new shock or bike, some retailers and manufacturers will offer an exchange program within a certain time window. If not, a traditional replacement coil is usually less than $35.

Now, Go Ride

The most important lesson to take away from this is to keep your eyes and ears open when you’re riding. Pay attention to the moments when your bike does something you don’t want it to or doesn’t do something you wish it could. Try making changes to settings that might be related to your issue.

And if by chance, they solve one problem but cause another, that doesn’t necessarily mean you should give up and change back. At least not right away. You have several tools at your disposal when setting up your suspension. Focus on adjusting each dimension one at a time, and getting yourself in different situations that will expose each setting’s strengths and weaknesses.

Pay attention to your comfort, efficiency and speed. But also pay attention to your emotions. Follow the settings that make your bike feel right. Trust your instincts.

Trust your heart … Maybe this really is more art than science.