What's sag?

Sag means when you sit on the bike how far downward does the rear suspension move under your weight. In a nutshell having the seat higher up would make the bike corner better and having it lower would make the bike more stable in a straight line. Too much one way or the other is not good.

KXO2 dosnt have a clue except he can spell sag.it is to bad when sombody is asking for help and people awnswer who are lost them selves.so both of you pay attention.ther are 2 sags,when your bike is on a stand(NO LOAD ON THE REAR TIRE)measure the distance from the sub frame to the swing arm.then put the bike on the ground it should sag about a 1/2 inch.the next step you will need help with.get all of your normal riding gear on and get somebody to measure the sag with you on the bike not being supported by any thing,a balancing act it should be another2 to 2 1/2 inchs.if your sag is not set this way higher or lower you are out of the curve it was designed to work at.the dampining and comprestion in the suspention change during the full stoke of the swing arm,so it is important that you start off in the correct postion.and that is what sag is all about

Well at least I can spell! And I don't consider myself lost either. I find that measuring sag at two points as you mentioned is useless. Are there 2 adjustments for sag on your bike? What part of what I said do you disagree with? I didn't have time to spend a half hour writing a full discourse on sag, but I stand by what I said. Sag is the amount that rear suspension sags, get it, when you sit on the bike as compared to when it is completely unloaded like when it is on a stand. By the way, Dawg_end I'm not positve on the correct sag for your bike. Most bikes need in the area of 100mm or roughly 4 inches not 2.5 inches as sunnyboy mentioned. :laugh:

well i guess you ride a lot in a straight line maybe you shouuld try 5 or 6 inchs of sag it will work even better acordding to your formula.you must set your bike up with no sag for corners.do as you please but what i printed is the way it is to bedone.by running to much sag your rear is starting out to stiff you are to far into the curve.ive only been doing this for 40 years so what do i know

Q: What is "Race Sag" (Static Sag)?
A: Static Sag or Race Sag is the amount the bike compresses from fully extended, with the rider on board.

Here's how to measure it.

1.)First extend the forks or shock completely and measure from the wiper to the bottom of the triple clamp on forks or from the axle to a vertical reference point on the chassis. This is L1.
2.)Take the bike off the stand, put the rider on board in riding position. Get an assistant to balance the bike or have the rider hold onto something, comress the suspension about 25 mm (1") and let it extend very slowly (slowly is the critical term). Where it stops, measure the distance between the wiper and the bottom of the triple clamp or the axle and the reference point on the chassis again. Do not bounce. This is L2. (If there were no friction in the seals the bike would come up a little further.)
3.)Next lift up on the suspension and let it drop very slowly. Where it stops measure again. Do not bounce. This is L3. The reason L2 and L3 are different is due to stiction or drag in the seals and bushings. (If there were no friction in the seals or the linkage the bike would drop a little further.)
4.)Half way between L1 and L2 is where it would come to rest with no friction. Therefore L2 and L3 must be averaged and subtracted from L1 to calculate true Static Sag.
Static Sag = L1 - (L3 + L2)/2
5.)To adjust Static Sag make longer or shorter preload spacers or use the preload adjusters, if available.
It is important to note that there are no magic Sag numbers. However here are some guidelines to use as starting points.
Front: 22-25%
Front mm: 65-75mm
Rear:30-33%
Rear mm: 95-100mm
Rear Free Sag: 15-25mm

this information was gathered from:
http://www.race-tech.com/SubMenu.asp?cMenu=4&c=Yes&cSubMenu=11&showPage=dirt#3

Your welcome

:laugh: Dawg, you KNOW I enjoy rattleing the bars on the cage, don't you? Anyway, I had the same question a couple weeks ago when I found that site. Seems everyone has their own method and they probably all work fine. I figured the link would end any arguements between KX02 and (notso) sunnyboy.

skipro3,
Thanks for the info. I don't know of anyone using that method, but it's obviously very exacting and scientific. Like you said, lots of oppinions. :thumb:

KX02 said:

skipro3,
Thanks for the info. I don't know of anyone using that method, but it's obviously very exacting and scientific. Like you said, lots of oppinions. :thumb:

Click to expand...

Hi KX02,
After all that technical instruction on how to set the sag, I found it kind of funny that the author hedged his bet with, "It is important to note that there are no magic Sag numbers."
Then I reviewed your first response to Dawg and I can see what you were getting at; sag can be an adjustment that depends upon what you are trying to accomplish. Canyncarvr shed a little light on this for me in another thread when I had some trouble with steep hill climbs and keeping the front wheel on the ground.
The details on how to measure sag is only important in that the proceedure will provide repeatable results. How much race / free sag and how much static sag you set up your bike for depends on what type of riding is going to be attempted, and that is what you were addressing when you pointed out that more sag would help out in straight line performance and less sag would help out in cornering. As with all things, we find compromise somewhere in the middle for all around performance and that is what the shock designers had in mind. Of course there is only so much tunable range here to play with as you are aware. I don't know why sunnyboy would assume that anyone would take the sag to an extreme of 5 or 6 inches. That would be ridiculous....but then beginning a post with, "KXO2 dosnt(sic) have a clue except he can spell sag." warned everyone that was where he was wanting to take things to with his bad behavior.
Glad to see you stand your ground! :thumb:

re: It is important to note that there are no magic Sag numbers.

Which means don't set it and forget it. A little experimentation may well return a favorable result.

If you start with a rear sag of 100mm, give it a try at 95mm to see if you like it better. Maybe so, maybe no. But at least your point of view will come from knowledge as opposed to 'I did it cuz what's what I read someplace.'

..not that there is anything wrong with some reading/research! Skipro's research should tell you what you need to know. Even covers 'stiction' which quite a few explanations don't.