How To—Dirt Bike Suspension Setup And Tuning

Dirt Bike Suspension Tips That Improve Your Ride

You can have the best dirt bike suspension in the world, but if you don't maintain it or understand how it works, it's not worth much. We've broken down how to tune and set up your suspension on your dirt bike for any style of riding, starting with the fork and ending with the shock. We also have some tips on how to get the most out of your stock suspension, and possible modifications you can make.

When setting up your dirt bike suspension, inflate your tires to the correct psi.
When setting up your dirt bike suspension, inflate your tires to the correct psi.Dirt Rider Staff

Dirt Bike Forks

Dirt bike forks are the first course of attack for setting up and tuning your dirt bike suspension. Starting with the front tire, make sure it's in good condition and inflated to an appropriate level. We recommend inflating your tire to 11–13 psi for motocross riding and 13–14 psi or more for off-road riding to prevent flats.

While you're down there, make sure your front wheel is installed correctly. Your wheel should sit squarely within the fork legs. If it's not, begin by loosening the axle and pinch bolts on both sides of the fork, then tightening your axle nut, then torquing the left-side axle pinch bolts to spec. Compress the right fork to set the leg and tighten the right pinch bolts when you are sure the fork leg is not binding and in its natural position.

One way to adjust your dirt bike suspension is to raise or lower your fork in the triple clamp.
One way to adjust your dirt bike suspension is to raise or lower your fork in the triple clamp.Dirt Rider Staff

Getting to the forks themselves, you'll need to adjust your rebound and compression damping according to your riding needs. The first step you need to make before tuning your dirt bike suspension is checking your owner's manual. The manufacturer will break down your suggested factory suspension setup, and it will inform you on how to adjust your fork.

When you adjust your fork, you can either raise or lower it in the triple clamps, changing the geometry of the dirt bike, or you can dial in your rebound and compression settings on the screws or clickers located on your fork.

Compression refers to how much your fork wants to compress. Less compression damping makes for a softer ride, but if it's set too soft, then the dirt bike will pitch under braking and bottom out when riding. Rebound refers to how much your fork wants to spring back to its original shape. Not enough rebound damping will yield a softer ride, but the bike will bounce around, leading to front end uneasiness and your cornering ability will suffer. You want to find a balance between these two settings—one that you are comfortable riding with.

To give you a consistent front end feel, you should bleed the air out of your fork before you ride.
To give you a consistent front end feel, you should bleed the air out of your fork before you ride.Dirt Rider Staff

To keep your fork in the best shape, make sure to bleed the air out of your fork at the beginning of the day before you ride. Always bleed the fork with your bike on a stand and your front wheel off the ground. Air expands with heat and altitude, so it is important to start your ride with no excess pressure.

Dirt Bike Shocks

Dirt bike shocks support the rider’s weight, absorb impacts, and make sure the rear tire stays in contact with the ground. Just like checking the fork, start with your tire. Make sure it’s in good condition and properly inflated. Heavy-duty tubes and mousses will affect your bike’s suspension, so aim for the lightest possible setup you can without risking punctures.

Keep your chain adjusted when you tune your dirt bike suspension.
Keep your chain adjusted when you tune your dirt bike suspension.Dirt Rider Staff

Check that your rear wheel is aligned and that the chain adjuster bolts are backed out to the same distance on both sides of the swingarm. If not, loosen your axle nut, adjust the chain adjustment bolt on either side, tighten the lock nut to secure it in place, and then retighten the axle nut. If you're adjusting the chain at the same time, adjust your drive chain on a stand with 30–40mm of play so it will not bind when the rear suspension is fully compressed

When adjusting your shock, it’s recommended to check the manufacturer’s factory settings, and then adjust or tune from there. The manufacturer will also detail how to set the sag.

Dial in your dirt bike shock by changing your rebound and compression damping for your riding style.
Dial in your dirt bike shock by changing your rebound and compression damping for your riding style.Dirt Rider Staff

The same rules for your fork apply to your rear shock as well, and your suspension should be fairly balanced between the front and rear. Adjust your compression and rebound for comfort as well as ridability. Also, adjust your suspension clickers gradually and don't force the compression or rebound adjuster past the minimum or maximum extent of adjustment, or you'll risk damaging internal parts.

Dirt Bike Suspension Tuning

To tune your dirt bike suspension, you’re going to have to get a little more involved than just turning a couple of screws.

Change the weight and height of your fork oil, change the front end feel.
Change the weight and height of your fork oil, change the front end feel.Dirt Rider Staff

One way to dial in your fork is adjusting the weight and height of oil in the fork. Adjusting the fork oil height alters the amount of air space in the fork and changes the damping characteristic in the second half of the suspension travel. Adding oil stiffens the fork and increases bottoming resistance, while removing oil softens the fork. Add or subtract oil in small 10cc gradients until you get your desired effect. You can add fork oil through the air bleeder with a small syringe. To remove oil, you will need to remove the fork legs from the bike and turn them upside down to drain oil out of the air bleed holes.

Moving to the rear of the bike, you’ll see the spring holds up the rider and bike, so make sure you have the proper rate spring in your bike. Most bikes work best with 95–115mm of sag when the rider is on it. Once you have the rider sag, check the static sag of the bike without the rider. Static sag should range between 25–45mm. If the static sag is less than 25mm, you need a stiffer spring, and if it is greater than 45mm, you need a softer spring.

How To Adjust Dirt Bike Suspension For Your Weight

If you're looking to adjust your dirt bike suspension for your weight, you're going to be setting the sag. Setting the sag means you're adjusting the amount of distance (sag) that the bike moves downward from the rider's weight. Setting your sag is simple, but it is recommended to have two people.

To improve your dirt bike suspension, you should adjust the sag for your weight and riding style.
To improve your dirt bike suspension, you should adjust the sag for your weight and riding style.Dirt Rider Staff

To measure sag, you want to start out with a static measurement. Placing the dirt bike on a stand, with no wheels on the ground, measure from the middle of the rear axle to a fixed point—normally where the rear fender and side panel meet. Record that measurement. Then, with all of your gear on, chock your front wheel and stand on the pegs. The second person will take another measurement using that same fixed point on the rear of the bike. The difference between these two measurements is called the sag.

The correct amount is approximately 33 percent of the bike’s total available travel, usually between 95–115mm on full size bikes, but this changes depending on the bike, rider preference, or where you’ll be riding. There is no correct measurement.

To adjust your sag, you will need a hammer and punch, or a specialty tool offered by the manufacturer. After you loosen the shock spring lockring, turn the spring preload ring to increase or decrease sag. A general rule of thumb is that one complete turn changes the sag by about 3mm.

Tuning your dirt bike suspension and adjusting your sag is more about getting the dirt bike's suspension within a comfortable range, not getting it to a specific measurement. Always make sure to ride, test, and make any adjustments as needed. When you are off your bike, stay on top of the maintenance, including changing your fork oil, bushings, and seals. Not only will this prolong the life of the bike, but it will keep your riding and suspension performance consistent.