How to adjust dirt bike suspension sag on your own without help
How to set sag on a dirt bike on your own is often asked. Which is what this article aims to answer. Why is this question important? Well setting sag on a dirt bike is one of the most important things to do. But the question often asked is how to set dirt bike sag by yourself to your weight. Let’s take a look for the rear suspension…
How you set dirt bike sag by yourself to your weight is best done with a Motool Slacker V4 digital suspension tuner. Step one: Measure your bike’s free sag, static sag and rider sag (race sag). If your weight is heavier than average you need to shorten sag. If your weight is less than average you need to lengthen sag.
- To shorten sag you need to tighten the shock lock nut or turn it clockwise.
- To lengthen sag you need to loosen the shock lock nut or turn it anticlockwise.
How to set dirt bike sag by yourself to your weight can be done using the Motool Slacker V3 digital suspension tuner
Whilst using the Motool Slacker V3 digital suspension tuner is more expensive than adjusting your dirt bike sag with mates, it does mean you can adjust your dirt bike sag on your own without help from others.
How does the Motool Slacker V3 digital suspension tuner work?
The Motool Slacker V3 digital suspension tuner comes with the main unit and a remote display. Both units have a digital display and a button to turn the unit on and one to switch on the back light
To zero the unit, you can either press the power button, or enter the auto zero mode by pressing and holding the back light button. The unit starts at zero when you first switch it on. However the auto-zero mode is useful for setting the free sag position on the unit.
Steps to measure sag on your dirt bike using the Motool Slacker V3 digital suspension tuner:
- Turn the Motool Slacker V3 digital suspension tuner on using the left button.
- Place one of the clear adhesive loops on the fender or mud guard of your dirt bike directly above the rear axle. Before attempting to attached the adhesive loop, make sure to clean the surface first.
- Connect the main unit to axle bolt and hook the retractable cable on to the adhesive loop.
- Turn the Slacker on and angle it to point directly at the adhesive loop so the retractable cable is straight.
- Strap the remote display to your handle bars and connect the electric cable from the main unit to the remote unit. Make sure to loop the cable along your bike frame so you don’t catch it. When the cable is attached to the remote it will automatically boot up.
- Press the back light button to enter into auto-zero mode and lift the rear wheel off the ground. This will zero your Slacker to the free sag position of your dirt bike.
- You are now ready to take sag measurements in real time. You can sit on your dirt bike to measure rider sag. Then follow the procedure to adjust the rear suspension sag to suit your weight.
Video to demonstrate the Motool Slacker V3 digital suspension tuner
Features of the Motool Slacker V3 digital suspension tuner
- The Slacker can measure from zero to a maximum of 150mm.
- Has a back light for dim light conditions.
- Can be used on axles up to 25mm or one inch in diameter. To use it on axles over this size you will need an axle insert. If you need this, you can call Motool on 1 800-741-7702 from within America or email them on [email protected]
- To turn the Slacker off you use the same button and hold it down for five seconds or it will turn itself off after 5 minutes of inactivity.
How to adjust dirt bike suspension to your weight by yourself
These are the steps to adjusting your dirt bike sag without help on your own to suit your weight and riding position.
How to set sag on a dirt bike by yourself in more detail
There are three measurements you need to set sag on a dirt bike, which are:
- First measure Free Sag: Which is when your bike is on a stand and the rear wheel is off the ground.
- Next is to measure Rider Sag (or Race Sage): Which is when you’re sat on your dirt bike with your feet off the ground and on the foot pegs. Note this should be done with you wearing your normal riding gear and dirt bike boots.
- Third is to measure Static Sag: This is when the bike’s rear wheel is on the ground under its own weight only (i.e. no rider is sat on the bike).
What are the first steps to setting the sag on a dirt bike?
It’s important to note that you need to check and set your dirt bike’s Rider Sag or Race Sag first BEFORE you set check the Static Sag.
Steps to set sag on a dirt bike on your own own without help:
- If the Rider Sag is less than what it needs to be (i.e. less than 100mm* (4″) or what your owner’s manual says, which could be in the region 95-115mm) you need to adjust the rear shock spring preload. This could mean you’re lighter than average.
- If the Rider Sag is more than what it needs to be (i.e. more than 100mm* (4″) or what your owner’s manual says) you need to shorten the spring on the shock. This could mean you’re heavier than average.
- On most Japanese made dirt bikes you’ll have two lock nuts. To adjust the sag on a Japanese dirt bike, first loosen the top locking nut. Do this using a screw driver, a punch tool or pre-loaded adjuster tool. On KTMs or Husqvarna dirt bikes you’ll have to loosen a pinch bolt using an Alan-key instead.
- Depending on whether you want to lengthen or shorten the spring, you need to either loosen or tighten the second lock nut. Or on a KTM or Husqvarna loosen or tighten what is usually a plastic lock nut once you’ve loosened the pinch bolt.
- Before you start to loosen or tighten the lock nut, mark one of the teeth or notches on the nut with your marker pen or sharpie. This will let you know when the lock nut has done a full rotation.
- Note that one full rotation equals between 2-3mm of sag adjustment.
- Once you’ve adjusted the shock adjusting nut, re-check your Rider Sag. Keep adjusting the nut until your sag is at the correct level for your weight, noting this should be in full dirt bike riding gear.
- Re-check your Static Sag too, as this should still be around 30-40mm of sag.
To be clear when adjusting your dirt bike’s suspension to your weight in order to get the rider sag correct for your weight:
- Rider Sag is too short and needs to be lengthened: Likely if your weight is lighter than average. If this is the case you need to loosen the second lock nut, which means you need to turn the nut anticlockwise with whichever tool you choose to do this.
- Rider Sag is too much and needs to be shortened: Likely if your weight is heavier than average. If this is the case you need to tighten the second lock nut, which means you need to turn the nut clockwise with whichever tool you choose to do this.
- Note in both cases with KTM and Husqvarna: You’re not adjusting a second lock nut. There’s just one nut (usually plastic) that’s locked using a pinch bolt instead.
* Note: Rider Sag can be more or less than 100mm (4″). This depends on the type of dirt bike you have, plus on the total available travel the bike has. If the total available travel is less than 305mm (12″), the Rider Sag will be less than 100mm. But if total travel is more than 305mm (12″), Rider Sag will be greater than 100mm. For this, check your dirt bike manual for your make of dirt bike.
What if Rider Sag is correct for your weight after adjustment but Static Sag isn’t?
Static Sag should be between 30-40mm for 125cc to 450cc dirt bikes; 25-35mm for 50cc to 100cc dirt bikes. But check your owners manual first.
There are two possibilities with regards to Static Sag after adjusting your dirt bike suspension for your weight. The first is that your Static Sag is too small after adjustment. The second is where the Static Sag is to much.
Rider Sag correct for your weight but Static Sag is to short
If your Rider Sag is at the correct level, but your Static Sag is less than what your owners manual says it should be. Let’s say it’s at 20mm. This means you’ve put so much pre-load on the spring to support your weight (i.e. you’re a heavier than average). Which means you now have too little static sag.
To correct this you may need to install a harder spring. Then you’ll need to re-check and set your Rider Sag with the new spring installed and re-check the Static Sag too. But then if you have a harder spring this will give you a harder ride.
Rider Sag correct for your weight but Static Sag is to long
If your Rider Sag is at the correct level, but your Static Sag is more than what your owners manual says. Let’s say for example at 50mm. This means you’ve put too little pre-load on the spring because you must be smaller and lighter than average, which means you now have too much Static Sag.
To correct this you may want to look at getting a softer spring. Once you’ve installed the softer spring, you will need to re-check and adjust your Rider Sag and then re-check your Static Sage too.
What is dirt bike sag?
When we talk about sag, we are talking about how much your dirt bike “sags”. Or put another way, it’s how much your shock absorber compresses. This is either when the bike is sitting on the ground by itself under its own weight (Static Sag). Or when you are sat on the bike (Rider Sag or Race Sag).
Then there’s “Total Sag”, which is with the bike on a stand and with the rear wheel is off the ground so there’s zero weight on the shock.
For most dirt bikes in the range of 250cc to 450cc, your sag will be in the region of 100mm (4″). The total travel on your rear shock’s going to have about 305mm (12″) of travel. Which means that Rider Sag of 100mm (4″0) will take up 1/3 of the Total Travel or 33.33%.
But always refer to your owners manual for the type and model of dirt bike you have. This will give you a window of what your sag should be for your dirt bike. Once you have your sag within the manufacturers “sag window“, you can fine tune it to suit your style of riding.
Why is dirt bike sag important to set correctly?
As I began this article, I said that setting sag on a dirt bike is one of the most important things you can do.
But why is dirt bike sag so important?
By setting your dirt bike’s sag correctly makes sure the balance of the bike is right. It will make sure your bike will handle the way you want it to and it’s going to make for safer riding too.
What does it mean to have more sag?
If you increase the sag, this means your rear end will sit lower. This will mean your dirt bike will be a little bit more stable at higher speeds.
More sag is better if you’re a desert racer.
What does it mean to have less sag?
If you have less sag, this means your dirt bike will steer and corner a bit better.
Less sag is better for tracks.
The dos and don’ts of dirt bike sag
I’ve included a few of the most important do’s and don’t of adjusting dirt bike sag in this article. But to see the whole list of do’s and don’ts please refer to this article: Full list of do’s & don’ts of adjusting dirt bike sag (Article in dirt bike sag 101 series).
- Always check rider sag with you on your bike so the the correct sag is set for your weight and preferred riding position. This should be measured with you in your complete riding gear and with your feet on the foot pegs and hands on the handle bars of the bike. But it should also be with at least half a tank of fuel too.
- Don’t adjust the sag on your dirt bike outside the “sag window“ recommended by the manufacturer of your bike. You can find this in your owner’s manual.
- Don’t check your dirt bikes’ sag when the suspension is hot: i.e. after you’ve ridden the bike, as it gets hot quite quickly. Heat build up will change the sag amount.
- Always measure to a fixed point on the bike when checking the sag to make sure you’re comparing “apples with apples” and not comparing “apples with pears”. This is taken care of with the Motool Slacker V4 digital suspension tuner, as you attach the loop onto the fender or mud guard.
What if you don’t want to buy a Motool Slacker tool?
If you don’t want to buy a Motool Slacker Tool to check your dirt bike’s sag you will need two friends to help you. The first friend is there to hold the bike when you’re sat on it to check Rider’s Sag. The second friend is to check the measurements of sag.
You can measure sag by simply using a tape measure and a paper and pen. Alternatively you can buy yourself a Sag Scale to make the measuring a bit easier.
I hope you enjoyed this article about how to set dirt bike sag by yourself to your weight
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