Suspension on a dirt bike is arguably the most important factor in how your bike handles. And one of the three main settings that can adjust your suspension is sag. It’s basically the springiness of your suspension
Riding your dirt bike without proper sag will make it harder to ride. When you ride a dirt bike, you want to be in control of the bike, not the bike controlling your ride. Therefore, setting sag perfectly is something that must be done right.
In this article, I will show you how to set the sag on a dirt bike which will provide you with maximum support while riding on bumpy terrain, pothole, and tight corners.
What is the sag of a dirt bike?
Sag is the amount that your suspension compresses under your weight when you’re sitting on the bike at rest. The ideal sag setting for your bike will depend on your weight and riding style, but generally speaking, you want around 30% of your total travel in the rear and 20-25% in the front.
For example, if your rear suspension has 9 inches of travel, you want 2.7 inches of sag.
Why do you need to set the sag on a dirt bike?
There are a few reasons why having the correct sag setting is important. First, it helps you use all of your suspension travel. If your sag is too high, you won’t be able to compress the suspension fully when hitting bumps and whoops. This can lead to a harsh ride and bottoming out the suspension.
On the other hand, if your sag is too low, you’ll be riding on the springs most of the time and not getting full use of the suspension travel. This can make the bike feel unstable and cause it to ride high in the stroke.
In addition to using all of your travel, setting the sag correctly will help balance the bike so that you’re not too far forward or too far back on the bike. This will help you maintain control and keep the bike from pushing in corners or washing out on slippery terrain.
Adjust the sag of the dirt bike: A Step by Step Guide
Now that you know everything about dirt bike sag, let’s take a closer look at how it’s adjusted:
Measuring the sag
Without precise measurement, it would be next to impossible to set a proper sag on the dirt bike. So, here you will explore how to take the measurements for dirt bike sag.
Step 1: Keep the bike on the stand
Begin the measurement process by putting the bike on a stand so that the wheels are not in touch with the ground. While doing this, you can take help from your friend or family member. Because the shocks are fully uncompressed, you can measure them smoothly since the bike is completely off the ground.
Step 2: Take the unloaded measurement
Take measurements all the way up to the fender of the dirt bike using a measurement tape. On the back wheel axle, you need to hold the end of the tape.
Once you have stretched the tape measure to the point where the side panel meets the fend, simply measure the distance in millimeters. Then note down the measurement on your smartphone’s notebook or paper.
The measurement that you will have is known as unloaded sag. Because your dirt bike didn’t have any weight, so did the shock springs.
Step 3: Keep the bike on the ground
Take the dirt bike off the front of the stand and keep it on the even surface. Make sure both wheels are touching the ground comfortably. You must ensure that during the sag setting process your bike must have to be on a flat surface because a sloped surface will give the wrong result.
Step 4: Get on the bike
Grab all your dirt biking gears like gloves, helmet, boots, riding pants, and jersey, and get on the bike. Sit on the bike as you are going for a ride by keeping your hands on your bike’s handles while leaning a beat forward while sitting.
You also need to ensure your trail bike’s fuel tank is filled just like the track time so that you can get the highest accuracy while measuring and adjusting the sag. While sitting, you barely keep your feet in touch with the surface just to keep the dirt bike stable.
Step 5 : Measure the rider sag
In this step, you have to bounce a bit up & down so that the shocks get into their normal position and become smooth which will give a more appropriate measurement.
Now tell your friend or helper to take the measurement from the rear axle all the way up to the point where both side panel and fender connect. Or in other words, take the measurement of the same two points you did in Step 2.
Then note down the numbers in millimeters on your smartphone or paper. Currently, the measurement you got is known as the rider sag/ racer sag.
Step 6: Check the static sag
Now you will take the same measurement of the rear axle to that specific point while the bike will be on the ground.
In this state, forks will have only the weight of the bike and nothing else. After taking the measurement, note it on paper or on your smartphone. The measurements that you got now mean static sag. People also call it free sag.
Step 7: Calculate to find out actual rider sag and actual static sag
This is the final step of the sag measurement process. Now you will be going to find out the actual static sag and the actual rider sag measurement.
It’s very simple, all you need to do is to subtract rider sag from the unloaded measurement to find out the actual rider sag.
For example: If your dirt bike unloaded measurement showed 610mm and when you were on the bike it showed 500mm then the rider sag would be (610-100= 110mm).
And, if your trail bike unloaded measurement showed 610 mm and the bike’s it self measurement showed 565mm then the static sag of your bike would be ( 610-565mm= 45mm)
Adjusting the sag
After covering the measurement part now I will show you the main part which is how to adjust the sagging step by step.
Step 1: Locate and loosen the upper lock nut
You can start the adjusting process by working on the nut which is right on top of the shock spring. All you need to do is strongly hold a piece of punch in your left hand and then put it on the tip of any of the tabs of the upper lock nut.
Then take a hammer on other hand and hit it on the punch with your hammer to make the lock nut loose in a counterclockwise direction. Remember you have to hit the punch multiple times to loosen the upper lock nut.
Step 2: Use a finger for further loosening
Now simply keep turning clockwise using the fingertips of your hand to make it loose further. Here, you can do 2-3 turns and it would be enough.
In case you find the nut a bit hard then the spraying of WD-40 lubricant. In this step, main target is to make enough turning space for the bottom lock nut which will help you to adjust your dirt bike sag.
Step 3: Have a look at the recommended sag of your dirt bike
Now depending on your dirt bike’s engine power & size, you have to adjust the sag. For this, you can have a look at your owner manual for the recommended sag.
Usually, the range of 50cc-65cc has a recommended range of rider sag around 70 mm. While for such cc range the recommended static sag is 25-35mm.
Typically the powerful dirt bike ranging engine cc from 125cc up to 450cc comes with a recommended rider sag of 102 up to 105mm. And these ranges of dirt bikes have a recommended static sag of around 30-40mm.
Step 4: Increase and Decrease the sag according to needs
Now it’s time to adjust the bottom lock nut to increase the overall sag distance of the bike.
Again using the combination of the hammer and the punch, simply hit the bottom lock nut in an anti-clockwise direction for 1 or 1 & 1/4 turns. This change will reduce the preload and the spring length will increase as well as the sag distance.
On the other hand, if you want to reduce the sag distance then you have to tighten the same bottom lock nut by turning in a clockwise direction with the help of a hammer and a punch tool.
If you need a rider to sag around 102-105 mm which has a present sag around 107-108mm then just secure the bottom lock clockwise with a full 1 turn. Immediately the sag will be within the 104-105mm range.
Step 5: Fix the top lock nut with the bottom nut
Again you need to secure the top lock nut but this time in a clockwise direction until it gets in touch with the bottom lock nut. Here, for a perfect tightening, you can use both the hammer and the punch.
Step 6: Check actual rider sag and actual static sag
Finally, you have to measure both the rider sag and the static sag right after you are done with the adjustment. Take the measurement after getting on the bike and let your friend take the rider sag. After that, take the measurement of the static sag.
Now subtract the rider sag and the static sag to find out the new actual rider sag and the actual static sag. This way you can plus minus the sag of the dirt bike.
Having read the post, I’m sure you’ve gained a much better understanding of sagging. You can take advantage of this information as long as you will be riding your dirt bike for ages.
If anyone dares to ask you‘’ how to set the sag on a dirt bike’’ then show them your full skill.