Suspension setup, setting the sag
July 29, 2009 by Jon Rhodig
Of all the mechanical things that people “mod” on an ATV or motorcycle, suspension is one that seems to be the most intimidating. It seems to me that most riders I meet are afraid to mess with all those funky clickety screw thingys and rings with teeth on them. I cringe anytime I see an obviously over or under sprung machine improperly setup for the rider. Improper setup can in some cases make the ATV or motorcycle down right dangerous to ride. If they only knew how much better/faster the ATV will ride and handle after proper setup. It is almost like they think they will “mess it up” or break the machine, which is far from what will happen, so they just ride it thinking the current setup is the best it can be. It is possible to “mess it up” without some basic knowledge of where to start.
First off the owners manual (and certainly the service manual) will have a section on the suspension specific to your machine. It will identify each adjustment and where it is located. If it is a “race” machine it may even have a brief section explaining basically what each adjustment will do along with a very brief section on what adjustments to make for certain conditions. I will add that what instructions or “tips” they do give in the manual are very vague even for me (although I am no suspension guru but I know how forks and shocks work as well as how the adjustments affect handling) That is why in this article I will go through the first and most important step in setting up and adjusting your suspension, Setting the sag.
Tools needed:
Tape measure (preferably with metric markings)
Spanner wrench for your shock adjuster ring(s) or substitute a hammer and long punch, rod or screwdriver (more on this later)
Permanent marker
Pen and Paper
A friend to help
All your normal gear you wear while riding including any bags, racks, or other accessories that you take with on the ATV or motorcycle.
Theory behind "race sag"
The idea of setting the sag is so when your riding your using all the suspension travel of the machine. In doing so, the machine will handle and ride to the best of its designed abilities. The procedure works for link-aged, link-less and IRS (with some variations to the process). Most modern machines have about 10 inches~(254mm) of travel in the rear (give or take), the ultimate goal is to set the preload of the shock(s) springs so when the machine is under load (fully laden with rider and gear) the machine is using about 33% of the total travel. In the case of a machine that has 10 inches~(254mm) the sag should be set at about 3 3/8 inches~(84mm).
Step 1: Determine what your total suspension travel is for your machine. This can usually be found on the INTERNET, service manual, owners manual, and sometimes the sales brochures. Multiply the total listed travel of the suspension (rear) by .33 (33%) this will give you the approximate measurement for the sag you will want to achieve. Write this down on a piece of paper for later. This is where using metric units becomes easier and more accurate.
Step2: With the machine on a flat level surface (concrete floor). Lift the rear end of the machine off the ground and gently set it back on the ground. The machine should sag slightly under its own weight. If it doesn’t this is an initial sign that the preload is set too tight or the spring is too stiff for the machine. Unladen sag should be around 1/2 inch~(15 mm).
Step3: Without disturbing the machine, measure from the floor to somewhere on the sub-frame. A good place is on the grab bar or rear fender. Make a mark with a magic marker where you took your measurement as this is where all your subsequent measurements will be taken. The actual location is some what irrelevant as long as you measure in the same place each time. For better accuracy the tape measure should be as perpendicular to the floor as possible. Write this down on the piece of paper.
Step4: Gear up with all your gear you normally wear or take with you while riding your machine. This includes any bags, hydration packs, or racks. Also it is best to have at least 1/2 tank of fuel. Gently get on the machine trying not to bounce the suspension. Sit in your normal riding position. Have your helper measure from the floor to the mark you made previously and write down the measurement on the paper.
Step5: Now subtract the laden measurement from the unladen measurement (Step3 – Step4 = current sag). This gives you the current sag. Write this number down on the paper. If this number is the same or very close to the ideal sag number you calculated in step 1 you are done and the sag for you on your machine is correct, if not continue to step 6.
Step6: In step 5 you determined if you had too much sag or too little sag. To adjust the springs preload either stiffer or looser depends slightly on the type of preload adjustment your shock has. It is best to use the proper spanner wrench for the adjuster and locking ring, but if neither is available a hammer and long punch or screwdriver can work if you are careful. Be sure to drive squarely on the “ears” of the adjuster rings. Tighten or loosen the ring and repeat Step 4 and Step 5 until you achieve the proper measurement. When you are all finished be sure to tighten the locking ring (screw type) before riding.
Step type adjusters
With the step type adjuster (found on most inexpensive and low performance machines) it may not be possible to get the adjustment spot on. Also if you find yourself adjusting the spring all the way tight or all the way loose, in both cases this indicates you need to change the spring to the next softer or harder spring to achieve the correct sag, Most modern screw type adjustable shocks have enough adjustment unless you weight less than 150#’s or more than 230#.
The procedure is essentially the same for IRS machines as well as the the front suspension on all ATV’s. The only real difference is you have two shocks to adjust and they must be adjusted the same.
Now with your sag set up properly for your weight it should ride and handle much better and now you can go the next more complicated (and sometimes subjective) process of adjusting the “clickers” for the damping, but we will save that for another day.
Of all the mechanical things that people “mod” on an ATV or motorcycle, suspension is one that seems to be the most intimidating. It seems to me that most riders I meet are afraid to mess with all those funky clickety screw thingys and rings with teeth on them. I cringe anytime I see an obviously over or under sprung machine improperly setup for the rider. Improper setup can in some cases make the ATV or motorcycle down right dangerous to ride. If they only knew how much better/faster the ATV will ride and handle after proper setup. It is almost like they think they will “mess it up” or break the machine, which is far from what will happen, so they just ride it thinking the current setup is the best it can be. It is possible to “mess it up” without some basic knowledge of where to start.
First off the owners manual (and certainly the service manual) will have a section on the suspension specific to your machine. It will identify each adjustment and where it is located. If it is a “race” machine it may even have a brief section explaining basically what each adjustment will do along with a very brief section on what adjustments to make for certain conditions. I will add that what instructions or “tips” they do give in the manual are very vague even for me (although I am no suspension guru but I know how forks and shocks work as well as how the adjustments affect handling) That is why in this article I will go through the first and most important step in setting up and adjusting your suspension, Setting the sag.
Tools needed:
Tape measure (preferably with metric markings)
Spanner wrench for your shock adjuster ring(s) or substitute a hammer and long punch, rod or screwdriver (more on this later)
Permanent marker
Pen and Paper
A friend to help
All your normal gear you wear while riding including any bags, racks, or other accessories that you take with on the ATV or motorcycle.
Theory behind "race sag"
The idea of setting the sag is so when your riding your using all the suspension travel of the machine. In doing so, the machine will handle and ride to the best of its designed abilities. The procedure works for link-aged, link-less and IRS (with some variations to the process). Most modern machines have about 10 inches~(254mm) of travel in the rear (give or take), the ultimate goal is to set the preload of the shock(s) springs so when the machine is under load (fully laden with rider and gear) the machine is using about 33% of the total travel. In the case of a machine that has 10 inches~(254mm) the sag should be set at about 3 3/8 inches~(84mm).
Step 1: Determine what your total suspension travel is for your machine. This can usually be found on the INTERNET, service manual, owners manual, and sometimes the sales brochures. Multiply the total listed travel of the suspension (rear) by .33 (33%) this will give you the approximate measurement for the sag you will want to achieve. Write this down on a piece of paper for later. This is where using metric units becomes easier and more accurate.
Step2: With the machine on a flat level surface (concrete floor). Lift the rear end of the machine off the ground and gently set it back on the ground. The machine should sag slightly under its own weight. If it doesn’t this is an initial sign that the preload is set too tight or the spring is too stiff for the machine. Unladen sag should be around 1/2 inch~(15 mm).
Step3: Without disturbing the machine, measure from the floor to somewhere on the sub-frame. A good place is on the grab bar or rear fender. Make a mark with a magic marker where you took your measurement as this is where all your subsequent measurements will be taken. The actual location is some what irrelevant as long as you measure in the same place each time. For better accuracy the tape measure should be as perpendicular to the floor as possible. Write this down on the piece of paper.
Step4: Gear up with all your gear you normally wear or take with you while riding your machine. This includes any bags, hydration packs, or racks. Also it is best to have at least 1/2 tank of fuel. Gently get on the machine trying not to bounce the suspension. Sit in your normal riding position. Have your helper measure from the floor to the mark you made previously and write down the measurement on the paper.
Step5: Now subtract the laden measurement from the unladen measurement (Step3 – Step4 = current sag). This gives you the current sag. Write this number down on the paper. If this number is the same or very close to the ideal sag number you calculated in step 1 you are done and the sag for you on your machine is correct, if not continue to step 6.
Step6: In step 5 you determined if you had too much sag or too little sag. To adjust the springs preload either stiffer or looser depends slightly on the type of preload adjustment your shock has. It is best to use the proper spanner wrench for the adjuster and locking ring, but if neither is available a hammer and long punch or screwdriver can work if you are careful. Be sure to drive squarely on the “ears” of the adjuster rings. Tighten or loosen the ring and repeat Step 4 and Step 5 until you achieve the proper measurement. When you are all finished be sure to tighten the locking ring (screw type) before riding.
Step type adjusters
With the step type adjuster (found on most inexpensive and low performance machines) it may not be possible to get the adjustment spot on. Also if you find yourself adjusting the spring all the way tight or all the way loose, in both cases this indicates you need to change the spring to the next softer or harder spring to achieve the correct sag, Most modern screw type adjustable shocks have enough adjustment unless you weight less than 150#’s or more than 230#.
The procedure is essentially the same for IRS machines as well as the the front suspension on all ATV’s. The only real difference is you have two shocks to adjust and they must be adjusted the same.
Now with your sag set up properly for your weight it should ride and handle much better and now you can go the next more complicated (and sometimes subjective) process of adjusting the “clickers” for the damping, but we will save that for another day.