A Step by Step Guide To Setting Up Suspension Sag On Your Dirt Dike


One of the most important things that distinguish a normal bike and dirt bike is a sag. You will find sag differs from bike to bike depends on the requirement of the rider. Today I’m showing you how to set sag.

Alright, guys, so today, I’m going to walk you through and I’m going to show you how to set the sag on your dirt bike. Now, before we get started, we got a few things we need to talk about. Now first and foremost, setting your sag is absolutely crucial.

It’s probably one of the most important things you’re going to do when you are setting up your dirt bike, it’s going to make sure the bounce of the bike is right that’s going to handle the way you want it to, it’s also it’s going to make for safer riding as well.

Now when I say sag, if you’re not familiar with that term, what it means is essentially it’s how much the bike sags. In other words, how much your shock compresses when the rider is both sitting on the motorcycle and also when the bike is just on the ground by itself.

Now you’re going to have different types of sag race sag or rider sag when the rider is actually sitting on the motorcycle and when the bike is on the ground by itself and nobody on it, that’s going to be called your static sag. Now for most of your big bikes on you, 250 to 450 is your adult riders, your size usually going to be a right around 100 millimeters and now it’s going to be about 4 inches.

Now when you think about it, your rear shock is going to have about 12 inches of travel so if you are on a 100 millimeter or 4 inches, that’s about a third of your travels going to be used in the rider sag. Now keep in mind though when every of your setting sag, it doesn’t matter what motorcycle it is, always look your owner’s manual, that’s going to give you a window of where your sag should be.

So once you get it within that window, then you can use some fine tune to get it to where you want it. Now, remember, more sag means the rear ends going to sit lower, now it’s going to mean the bike is going to be a little bit more stable at higher speeds. Then if you have less sag, and these bikes, the bike is going to steer or corner a little bit better.

So if you’re a desert racer, you maybe want a little more sag, if you’re a track guy, you might want a little bit less. Again, you’re just going to fine tune it to how you want the bike to handle. Now setting sag is fairly simple, all your doing really is just adjusting the preload on the spring that comes on the shock. And remember, everyone has a different shape and size no matter what bike you’re on, you’re always want to get the sag set up for you.

So now I’m going to show you guys how to do it step by step. Okay, so before we get started today, there are a couple of things you’re going to need when we, in order for you to set your sag. First, you’re going to need a friend or two and I’ll explain that here why in just a minute. Another is you’re going to need a way to measure your sag so you got two options. Today we’re going to be using the motion pro sag scale. It’s really nice and makes it convenient, if you don’t have one of those, a tape measure will work just fine.

If you’re going to use a tape measure, you’re going to want a piece of paper to write down your measurements and also you’re going to want a pen to do that. I’m going to be using a sharpie, a sharpie is also nice and you see why when we’re measuring the sag or mark our reference point on the fender to make sure it measures the same spot. And then, you’re going to need a punch tool or preloaded adjuster tool. If you don’t have one of these, you know you can use just a long screwdriver but these because they are curved to the end, it does make a little bit easier.

You need some sort of hammer, that’s going to be used to loosen or tighten the locknut strings on your shock. And if you’re going to be doing this solo, a really nice tool to have is Motul Digital sag scale. This is making it to where you can take a two or three man job, you can actually set the stack by yourself you know when you’re out. So riding you’re at the tracks. So those are the tools that we’re going to need to set our sag today.

Alright, so the first step that we need to do, is we need to measure the free sag on the motorcycle. And now free sag refers to when the bike is on a stand and there is zero weight on the shock. Now you have a couple of ways to do this as I’ve mentioned before, you can use a tape measure, I’ll show you how to do that with the tape measure first.

So what’s you’re going to want to do is you’re going to measure from the axle up to a reference point on your fender. So you can see right here, I’ve actually already marked the place, this is where we’re going to measure the sag from each and every time. So I’m going to place the tape measure here just in the axle, I’m going to raise it upright to that point, I’m going to be outridden it 60 centimeters.

So if I convert that to millimeters, that’s going to be 600 millimeters. So you want to take that number 600, you want to write that down in your piece of paper, you don’t want to forget it and then we’re going to subtract the rider sag from that here in just a second. Now, so that’s how you do with the tape measure and nowhere is why we like to use a Motion Pro slag scale so much. It really, it takes all that math that equates, you don’t need to be writing down any numbers. What’s you’re going to do is you’re going to take the sag scale and you’re going to see that reference point that we have and what you’re going to do is you’re just going to zero it out.

So I’m going to loosen this nut down the bottom, and then I can just slide this down, and once I have that zeroed, I can just tighten this backup. Now when I measure the rider sag in it, the rider sits on the motorcycle, I’m going to know exactly what might sit my sag is, I’m not going to have to do any equations from there.

Alright, so with step 2, now what we’re going to do is we’re going to measure the rider or the race sag. Now something to keep in mind before you do that, is you want to have the bike in yourself set up as if you’re going to go out riding.

So I’ve got my friend Justin here. Justin is wearing boots, pants, jersey helmet, you want to have the bike set up to so you want to have at least a half tank of gas or more you know if you wear a tool belt or you wear a backpack when you’re out riding, you’d also want to keep that in mind because you got to remember, anyway that you add is going to affect the sag on your motorcycle.

So remember, have the bike set up as if you’re going to go riding. Alright, so now what we’re going to do is  we’re going to have Justin get on the motorcycle and we’re going to get him in the correct position to where we want to take  that next measurement for the sag. So, have Justin get in the bike and also it’s a good time to point out, that’s why I’ve mentioned you might want to have a buddy with you.

Chance here is helping us out, he’s going to be holding the bike stable so when Justin gets on the bike, he doesn’t have to support himself that allows him just to be natural on the bike. So Justin hop on there. Now when Gavin is on the motorcycle, you want to always measure when you’re, the rider is in the same position because if you move, if you change your position on the seat, that’s all you’re going to change your sag. So you want to be a little bit forward of center on the seat, so a little bit farther towards the gas tank. And then you want to have your hands on the handle bars, you just want to pretend like you’re in your riding position.

Now once Justin set, a good idea is to always just give a couple presses on the rear, that’s going to compress the shock a little bit and get rid of the anyyou might have and just going to help the shock settle into its natural position. So now, once that’s done, I’m going to take that measurement on the sagging so I’ve got my sag scale here.

Again, I’m going to go the exact same point that I already marked on the fender. So with Justin on the bike right now, you can see we’re sitting right about 96 millimeters of sag. So like I said, we want to be right around a hundred that’s what this bike calls for. So what we need to do from here to get an extra 4 millimeters of sag, is we’re going to need to loosen or lengthen the spring on the shock which is going to allow for a little bit more sag, so we’re going to do that next. Okay, so what we’re going to do now is we’re going to lengthen the spring on the shock. Now, we’re at 96 millimeters of sag, we want to be at a hundred, so how are we going to get those extra 4 millimeters is we’re going to loosen the locknuts that are on here to allow the spring to be a little bit longer.

Now on your Japanese bikes, you’re going to have two locknuts, the upper locknut is what’s going to hold everything in place from your locking nut and the bottom, that’s going to be where your spring seats against and adjusting that either loosen or tighten it, or tightening that, is going to allow us to adjust the compression on the spring.

So what we’re going to do, oh and one thing to keep in mind as well is on your KTM, Husqvarna models, a lot of those will actually have a plastic locknut that has a pinch bolt. So it’s going to be the same thing you just going to need to loosen up pinch bolt before you adjust it. So what I’m going to do, is you’re going to have these two locknuts, I’m going to take my punch in my hammer, I’m going to put it here on the top locknut and I’m going to loosen this and move it up the shock, so hit this.

Now once that breaks free, you can actually just go ahead get your fingers in there and you can start to loosen it, it’s going to be a little bit faster. If this getting binding, if it’s binding enough or it’s hard to get going, a good idea is to just get some WD40 sprayed on the threads, that’s going to help you loosen up a lot easier. Okay, so now I’ve loosen that upper locknut, so now what I need to do is I need to do the same thing and I’m going to take this lower locknut and I’m going to loosen that as well and that’s going to allow the shock or the spring to lengthen which it will going to give us a little bit more sag, so I’m going to do that next.

Now what you can do another tip, is if you want, you take a sharpie like I showed you earlier, you can actually mark one of the notches on the nut, that’s going to let you know when you’ve done a full circle. And keep in mind that usually one full rotation is about 2 to 3 millimeters, so we’re going to do a full rotation and then see where we’re at from there, so.

Alright, so now I’ve Justin back on the motorcycle, so we adjust the sag the first time, we measured it again, we’re just still off just a little bit, so I loosen that locknut, one more rotation so in total we came out about two full rotations we loosened it. Now remember, if you don’t, if you have too much sag on your motorcycle, well then you would want to tighten that nut and that’s going to allow the bike to sag a little bit less. So now, Justin is back on the motorcycle, again, exact same riding position he was in earlier, so I’m going to take my sag scale and put it the exact same spot, you can see I am right at a 100 millimeters and that is right where we want to be.

So that’s what the sag scale. Now, if you’re using a tape measure, now you’ve got your first measurement that you took earlier and you wrote that down on piece of paper. So what you would do now, is you do the same thing, you’re going to measure from your axle to that reference point and whatever that number is in millimeters, you’re going to subtract that from that first number that you wrote down and that should be right around a 100 millimeters.

So in our case, the second measurement, if it were 500 millimeters, you subtract that from 600 which was the first number and that gives you a hundred millimeters of rider sag. So now what we need to do, is we need to put the bike on the ground with Justin off the motorcycle and we’re going to measure out static sag to make sure that’s where we wanted as well.

Okay, so now we’ve got race sag set, the next step is going to be checking your static sag on the motorcycle. Now like I said before, static sag is when the bike is off the stand and there’s nobody sitting on the motorcycle, you’re just checking the weight of the motorcycle on how much you compress the shock on its own.

So just like you did before, you’re going to take your sag scale or your tape measure from your axle, come to where you mark your fender previously, so right now we’re at 34 millimeters of static sag. So if you’re taking your tape measure, you’d measure that in millimeters and then subtract from the original measurement, for us it was 600 and that’s going to give you your static sag. Now for most big bikes, you’re going to be right between about 30 to 40 millimeters of static sag. Now but make sure check your owner’s manual, that’s going to tell you what you need to be at.

But in this case, we’re at where we need to be but if you were to say, well under that, say you’re at 20 millimeters but what that means is you put so much preload on the spring to support the rider’s weight that you now don’t have any static sag. And if you’re well over that say you’re at 50 millimeters, well you might want to look into a softer spring and then again if you will under that you want to look into a stiffer spring.

But now that you’ve got the race sag set, your static sag’s is right, is right where it needs to be, now what you want to do is just tighten up that locknut or that pinch bolt if you have a Husqvarna KTM and you’re ready to go out and ride. Alright guys, so that wraps up our how-to video on how to set sag on your motorcycle. Now I can’t reiterate it enough how important it is to make sure you have that set up correctly for you.

Again, it’s going to really affect how your bike handles, it’s also going to make it safer and always refer to your owner’s manual if you guys have question, if you need to know where your race sag should be at.

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