How-To: Mountain Bike Suspension Set Up with Art's Cyclery 16

Besides having air in your tires, there is nothing more crucial to enjoying your time on the bike than proper suspension set-up. The first step is to determine sag; the distance your bike settles into its travel when weighted. Verify that your fork and shock have travel indicators, or O-rings around a fork stanchion and shock shaft. If there are none, install a zip-tie yourself, but not too tightly. Let’s start with the shock. Place the bike next to a wall or have a friend hold the bike while you climb aboard. Wear what you would on a ride, including filled hydration pack, armor, and such. Stand on your pedals in the attack position, centering your weight over the bike. Gently bounce a few times, then slowly reach down and push the travel indicator up against the shock body, without compressing the shock. Slowly dismount the bike, moving forward, so you don’t compress the shock. With your air spring pressure set properly, your travel indicator should move 20-30% of the shock stroke, or exposed shock stanchion. Longer travel bikes need slightly more sag, usually around 35%. Increase or decrease air pressure five PSI at a time until proper sag is achieved. Write down the air pressure figure that it took to reach the proper sag point for your bike. For a coil shock, unscrew the shock preload collar all the way, and retighten just to the point where you feel resistance from the spring. Now measure the uncompressed eye-to-eye shock length. Then, subtract the compressed eye-to-eye length, and you’ll have your sag. You will need a helper to measure the compressed shock length. Divide the sag measurement by the total shock stroke for sag percentage. If you’re not getting enough sag, you’ll need a lighter spring. If you have too much sag, tighten the coil spring preload collar and repeat. Keep going until you achieve optimal sag for your bike. If you need more than two-to-three full turns (depending on manufacturer) to reach optimal sag, you’ll need a stiffer spring. Setting sag on your fork follows the air shock procedure, comparing the total exposed stanchion to the amount the travel indicator moves. Be sure to dismount the bike rearward so as not to compress the fork. Now that we’ve got our spring rates dialed in, it’s time to set rebound damping. Less damping—turning the adjuster counter clockwise— means the shock or fork will return from compression faster, and vice-versa. If rebound is too fast, you’ll get a skittish, bucking ride. Too slow, and your suspension won’t be ready for the next impact, giving a harsh ride. The easiest way to get in the ballpark is to use the “top-out test,” which can be performed on the shock and fork. Turn your rebound adjust knob so it is fully open. Now compress the shock as much as possible by pushing down on the saddle, and quickly let go. If the shock extends too quickly, coming to an abrupt stop at the top of its travel, you’ll need to increase damping (tighten the adjuster) to slow it down. You may also be able to feel or hear the shock top out. Repeat the process until the shock no longer springs back harshly. Write down how many clicks you tightened the adjuster. Another method is to ride off a curb while standing, gradually increasing rebound damping until your shock compresses and returns without bouncing. Repeat the top-out process on your fork, pressing down on the handlebars instead of the saddle. You will most likely need to fine-tune your rebound one or two more clicks on the trail. If the front or rear of the bike bucks or seems jumpy, increase the appropriate damping a click to slow the rebound down. If the bike seems like it’s overly harsh through successive hits, speed up the rebound a click so the suspension will be able to extend for the next impact. When you get home, write down your changes. It’s best to err on the slow side of rebound for the shock so you won’t get bucked, and on the fast side for the fork, so it won’t pack up and throw you forward. A general guideline is to set up your rebound 1 or 2 clicks faster for trails with small, high frequency bumps and 1 or 2 clicks slower for trails with big hits. Compression damping adjustments are more involved, and require time on the trail to dial in. Not all suspension components feature compression adjustments. Most trail components offer low-speed adjustment, and DH components offer separate high and low-speed adjustability. Speed refers to the how fast the damper shaft is travelling, so high-speed compression handles big, square-edged hits and bottom outs, while low-speed compression affects small bumps and pedaling “platform,” along with brake dive and ride height in corners. It’s helpful to think of low-speed damping as a blow-off gateway to access the high-speed damping. My favorite way to set up compression damping is to back the damping all the way off—loosen the adjuster knob—and get out on the trail, paying attention to specific ride characteristics, which apply to both the fork and the shock. First, if you find yourself bottoming out harshly or too often, increase high-speed compression damping by tightening the adjuster knob. Adding volume reducers to your fork and/or shock’s air chamber is another option to deal with this problem. This will increase the spring rate at the very end of the travel, possibly preventing bottom out. If you get to the point in your testing where you are never using all the travel, and the bike feels harsh, decrease high-speed compression damping. For low-speed damping adjustment, focus on brake dive and ride height as an indicator of your fork’s low-speed compression. If the fork compresses excessively when braking, or when driving through turns, increase low-speed compression damping until ride height remains stable and brake dive is under control. For your rear shock, small bump compliance and pedal bob will direct you in adjusting your shock’s low-speed compression. If your shock is not absorbing small bumps try decreasing low-speed damping. Increasing low-speed compression damping may help to reduce pedal bounce. It’s important to record all your suspension settings. This lets you see how changes affect your bike’s behavior, and will get you back to the sweet spot if your settings are altered. Once you finalize your settings, you might write them on pieces of tape affixed to your fork and shock so you’ll always know where you should be.

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  • Art's Cyclery

    4/16/2014 10:24 AM

    Hi D.Ironshirt. I'm not sure I understand the question. If you mean "smooth trail" by "flat ground," then yes, firmer suspension will provide more efficient pedaling, an acceptable trade-off when the necessity of clearing big obstacles is not present. Either increased spring rate or increased low speed compression damping will firm up your suspension. The correct choice depends on the situation.

  • D.Ironshirt

    4/16/2014 6:53 PM

    A bit stiffer in general? Since most of your need for the fork is descending. Should you not set it for that. On flat ground your sag will be very different then that of descending. Most likely weight is being pulled off the rear tire and shifting slightly towards the front also with variables in braking force applying more perceived weight. This is all saying your in the right body position for braking and descending.
    I feel there is only so much that high and low compression can adjust.

  • Art's Cyclery

    4/17/2014 9:07 AM

    Ah, now we are getting into the more advanced nuances that mojojojoaf alluded to below. While the full scope of suspension set up is too broad for this arena, you are on the right track, but, the steeper the terrain, the more rearward your weight should be. Thus setting up your fork stiffer will result in too harsh of a ride. Pay attention to your travel indicators. If you find yourself blowing through or not getting enough travel even when your compression settings are correct, try a little less or a little more air pressure until you get it dialed for your terrain and your style of riding. Just remember to keep track of your changes. Thanks for the comments!

  • D.Ironshirt

    4/15/2014 9:53 PM

    would you want your front suspension to bit a little stiffer on flat ground?

  • emersonfnogueira

    4/15/2014 5:08 PM


  • Art's Cyclery

    4/15/2014 11:43 AM

    Adam, thanks for the input, and you're correct: many people prefer to set up spring rates in the seated position, for the valid reasons you describe. We decided to present a set-up leaning toward descending and aggressive bike handling for Vital's readers.

  • Art's Cyclery

    4/15/2014 11:35 AM

    Hey Todd, thanks for paying such close attention to the video! I believe when you refer to the VIDEO portion, you are referencing the quote where I say "Now measure the uncompressed eye-to-eye shock length. Then, subtract the compressed eye-to-eye length, and you’ll have your sag." In that case, I was simply referring to the actual sag measurement, not percentage. As you noted, the formula for determining sag percentage is correct.

  • todd.margeson.9

    6/19/2014 9:18 PM

    Correct, what you state in your quote above is simply referring to the actual shock measurement, but I was talking about the sag percentage formula, which is shown in graphic form on the screen just after the quote you referenced. It shows [uncompressed shock length - compressed shock length] / uncompressed shock length x 100 = Sag Percentage. Which of course is incorrect. For instance, a 7.875" eye-to-eye x 2" stroke shock should have ~1/2" sag (25%). But [(7.875" - 7.375") / 7.875"] x 100 = 6.35%

  • todd.margeson.9

    4/14/2014 11:34 PM

    Good video overall, but there's a mistake in sag percentage calculation in the video. In the *text* of the article, it says to divide actual sag measurement (uncompressed shock length - compressed shock length) by total shock stroke. THAT'S correct. But in the VIDEO, it says to divide the sag measurement (uncompressed - compressed) by *uncompressed shock length*, which of course is not correct. That'll give you a tiny percentage. Simple oversight of course, as it is correct in the text, after all.

  • Art's Cyclery

    7/7/2014 2:04 PM

    We've updated the video to correct the sag calculation error. Thanks again for letting us know.

  • mojojojoaf

    4/14/2014 7:55 PM

    Another excellent video. Is this the be all end all suspension set-up? Nope but its a great place for those that need a place to start with great explanations.

  • Art's Cyclery

    4/15/2014 11:39 AM

    Thanks, Mojo. We agree, suspension set-up can be a much more involved process at the higher levels. This video will give a basic understanding of the important principles and how to implement them. Thanks!

  • Adam_Schaeffer

    4/14/2014 2:54 PM

    Typically Im setting sag with the rider in full height seated position. For most setups this will be more accurate, as much of your riding will be in the seat. Only time I'll do a standing sag is for full DH race, and even then its usually off. Seated position is more rearward, which will load the suspension more. This is important so you don't end up with too soft a spring rate for when you sit down and mash up a steep climb. It helps to keep your weight balanced on the bike.

  • Sababike

    4/14/2014 9:42 PM

    Hi Adam,

    I understand your point, however I would still recommend setting up sag while standing. Reason being that I'd like the suspension to be at it's best where I really need it to work well - on the technical sections, rocks, and descents - all of which I'll be doing standing up of course.
    So for me - a compromise on sitting and pedaling is worth the performance where I want to have fun!

  • app-uncture

    4/14/2014 10:05 PM

    Agree 100% with Sababike, I don't want my forks blowing through on the steep stuff and sending me over the front so I always set sag with a fair bit of weight over the front. Can i plug my Bike Setup app here, its ideal for recording your settings and experimenting

  • Adam_Schaeffer

    4/15/2014 11:37 AM

    30% sag while seated is usually the sweet spot - standing or seated. If you set your sag at 30% while standing it will typically be too soft because you're not fully loading the frame while taking the measurement. I find its usually correct for aggressive DH riding as well, because you're not blowing through the travel as easily.