Higher Education: How to Set Up Your Suspension
Getting to know your bike's boingy bits.
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Aside from having working brakes, there are few things more important than getting your suspension setup properly. It’s common for folks to become intimidated by their suspension, but a few basics can have you confidently establishing and maintaining your fork and shock setup in no time. The purpose of this post is just to get us familiar with those basics, and get out on the trail armed with them. We dive deeper into suspension fine-tuning in another post.
Get prepped, know what’s up
First things first, let’s get some basic things established. Here are a few guidelines when it comes to your bike’s suspension:
1. Check your suspension setup often. Like, every time you ride. Small changes can have large impacts on the ride quality of your bike and your experience out on the trail. If your sag is off by just a little bit, things get a whole lot less efficient. Going for a longer ride and carrying more weight in your pack? This will affect your suspension setup. Just like you’re preparing yourself by packing more food and water, you should also prepare your bike.
2. Don’t be scared. This stuff is way simpler than it might seem. Play around with it. Learn it. Understanding your suspension will pay off in the long run. One good tip for learning what all the adjustments do is to use the extremes. Run the rebound all the way fast, and all the way slow, and feel the difference. Do the same with compression, and even preload. And remember, suspension is user-specific. There are guidelines to getting your suspension dialed in, but ultimately, not many steadfast rules. In the end, it’s all about how it feels to you.
3. Suspension setup is also condition-specific. The more comfortable you become with your suspension, the more you can dial it in for every ride. Not everyone is going to want to do this. Sticking with one setup for all conditions is perfectly fine, but, just as you might run different tire pressures in different conditions, you can dial your suspension in for the terrain. You can, for instance, run softer suspension in low-grip environments, but trails with berms and hard g-outs might call for more support. Rough, high-speed terrain might call for faster rebound whereas you might slow it down a bit for jump trails. Again, the level of per-ride tweaking will vary from one person to another, but knowledge is power when it comes to getting the most out of your dampers.
4. Speaking of knowledge, read your fork and shock’s user manuals. Know what adjustments are available and where they are. And read up on your bike, too. Different bikes have different sag recommendations, some even have a more comprehensive recommended shock setup, based on that bike’s specific rear suspension system.
5. Finally, carry a shock pump with you when you ride. And whatever other tools you might need to make compression and rebound damping tweaks. This will come in handy when you start getting things really dialed-in, because making changes out on the trail allows for instant feedback. Besides, being prepared is always a good idea. The mini shock pump I keep in my ride pack is one of the most frequently used tools I carry.
Speak the Language
Now that we have that down, let’s make sure we’re speaking the same language. There are a ton of suspension-specific terms, but here are the few basics you’ll need to start with:
- Preload – Also known as spring force, or simply air pressure (in most cases). Most of us have air-sprung suspension, meaning that an air chamber, rather than a coil spring, is the force that keeps the shock or fork extended and allows it to spring back after an impact.
- Sag – This is how much the suspension compresses with just your weight on it. We adjust the spring force up or down to achieve the desired amount of sag.
- Shock stroke – How much travel your actual shock has. Not the bike. Your bike might have 150mm of rear travel, but that is achieved through linkage and stuff. The shock of a 150mm bike might only have 50mm of stroke. Knowing how much stroke your shock has is important because it will let you translate a percent of recommended sag to an actual number you can measure. Shocks are measured by length (eye-to-eye) and travel (stroke). An example is: 210 x 55. Meaning 55 is the stroke in millimeters. We’re not worried about eye-to-eye in this lesson.
- Damping – Not “dampening”. All suspension is made up of two main things: a spring, and a damper. Damping is what controls the forces going through the suspension, in the form of oil running through special valving. The damper is what keeps the spring from being a pogo stick and launching us to the moon every time our suspension rebounds from an impact. Its also controls the way it compresses when we hit stuff. Adding damping slows stuff down, while reducing damping speeds things up. Faster = less damping. Slower = more damping. Compression damping controls how fast the suspension can compress, or essentially, how quickly it can respond to an impact, while rebound damping is the opposite. Rebound damping controls how quickly your suspension recovers from an impact. How fast it bounces back.
Getting your suspension set up requires three main adjustments: Sag, compression, and rebound. Simple as that, right? Let’s dig in.
When it comes to rear suspension, your bike has a recommended sag range. Figure out what that is. And while you’re there, look up the shock stroke, too. You’ll need that. Most brands recommend somewhere between 25 and 30 percent sag. Percent of the total shock stroke, that is. If your shock has a stroke of 55mm and your bike should have 30 percent sag, your sag measurement is: 16.5mm.
You may not need to calculate your sag number. RockShox laser-etches gradients in its shocks, and some manufacturers will just give you the number, or better yet, they might give you a starting air pressure based on your weight (and sometimes height). Off the top of my head, I know that both Specialized and Ibis do a great job of this. Many other brands do as well. Some even give starting compression and rebound settings. Use them. They’re usually pretty close.
There are a couple things to know when setting sag. Full suspension bikes are very weight-sensitive. If you lost 5 pounds since the last time you rode, your romantic interest may or may not notice, but your bike will. That’s why we always set sag when dressed and ready to ride. We call this “rider weight”. It’s important to wear what you’ll be riding in, including whatever pack you might wear, water and all.
Once you know how much sag you should start out with, go ahead and bust out the shock pump and measuring tape (or better yet, a set of Vernier calipers). There’s a little sag-indicating o-ring on the stanchion of the shock. That’s what you’ll measure.
Make sure any fork or shock lockouts are not engaged, and get next to a wall or something you can lightly lean against to balance. Now, get on the bike and assume a riding position. Like you’re about to attack a descent. Weight balanced, pedals level, elbows out. All that business. Then, without holding the brakes, bounce up and down on the bike a bit. This will get the bike nice and settled into the sag. Next, slowly reach down while carefully trying not to shift your weight, and slide the o-ring up against the seal of the shock’s air can. Then, slowly unweight the bike. It’s important not to bounce on the bike at all after you set the o-ring. You can grab the brakes again to help stabilize everything. Then, step off the bike carefully without compressing the suspension any more.
Measure the distance between the seal and o-ring. That’s your sag. Repeat this process until you’re on target. It might take a few rounds.
This little side note is important: Any time you add or remove air from the shock, you must cycle it several times (like 10) before taking another measurement. We don’t need to get into negative air chambers in this lesson, but we do need to know that all air shocks have them, and most of them are filled automatically via a transfer port from the positive air chamber (the one your shock pump is connected to). Cycling the shock allows the positive and negative chambers to equalize. If you add a lot of pressure to a shock all at once, you might notice that it’s really hard to compress the first time and feels like a pogo stick, but cycling it a few times will normalize it. That’s the positive and negative chambers equalizing, and that’s another reason why we bounce up and down on the bike a few times before sliding the o-ring into place.
Related: How To Set Up Your Cockpit
Sag on Forks:
Setting sag on forks can be done in this same way. Generally, you’re looking for around 20 percent of the fork travel. But, fork sag is much more about feel than the shock sag is. Shock sag determines how the bike will pedal, your traction, and even how much influence the drivetrain has on the suspension. This isn’t exactly the case with forks, so you can really set the firmness of the spring more on feel than anything else. Also consider your terrain. If most of your descents are steep, more of your weight will be concentrated on the fork, and you will want less sag. If your descents are not so steep, your weight will be more balanced and you can get away with more sag. Or, start off with the chart on the fork leg and go from there.
Impacts are separated into two categories: low-speed and high-speed. Not how fast the bike is moving, per se, but how fast a certain type of bump makes the fork or shock move. Low-speed impacts come from rolling terrain and our body-weight moving around on the bike. High-speed impacts come from square-edged things like rocks and roots. When your wheel hits things like these, it requires the suspension to react quickly. Speeding up or slowing down a fork or shock’s damping determines how it’s able to track the ground underneath us. The vast majority of riders run their damping way too slow.
Some high-end suspension products have more external adjustment than others. For instance, many forks and shocks have low-speed compression and rebound knobs, while high-speed compression and rebound are set from the factory. No matter what you have at your fingertips, the basic rule of thumb for damping is to run it as fast as you can without your bike feeling like a pogo stick. Start fast, and add damping as you need to. Remember, adding damping means slowing the movement down. Clockwise always adds damping, counterclockwise always speeds it up.
Compression is often indicated by blue. If you have just one knob for compression, it’s a low-speed knob. A lot of what low-speed compression damping is responsible for is controlling how “bobby” your suspension feels. Adding low-speed compression will quiet how much your suspension moves as you’re bouncing around on the pedals. It’ll also keep a suspension fork higher in its travel on steeper terrain. But, be careful how much you add, because too much will make the suspension feel harsh on small impacts. I like active suspension, so I typically run my compression damping either wide open or just a couple clicks in from wide open.
The red knob. The same rule applies to rebound damping. Start off quick, and add damping as you need it. I generally encourage riders to get used to faster damping because it allows the tire to maintain better contact with the ground, but finding just the right setting will vary between riders. And, keep in mind that the more air in your fork or shock, the faster it’ll want to spring back. Therefore, heavier riders will require more rebound damping than lighter riders, and any significant change to preload may require an adjustment to rebound damping.
And there you have it, folks. Those are the basic principles around suspension set up. Next time, we’ll dive more into the tuning side of things.
Photos: Ryan Palmer