FAQ-Suspenstion Setup (from old Section8 site)

[DucHead]

Sag - the amount the suspension compresses when you sit on the bike. Typically this is measured from full extension (meaning someone is picking up the seat or handlebars) to compression with you on it. Sag is the most important thing to get right, and the first thing you should get set up properly. The sag depends on the spring size - if you're small/thin, too thick a spring may not sag enough for your weight; for a heavy person, the stock spring might be too thin and sag too much. Sag is set by adjusting "preload". Basically preload is the amount the spring is already compressed before you sit on the bike. You should see a couple of rings on a threaded section of the shock. The closer they are to the ground, the more the spring is compressed and the more "preload" there is, and correspondingly more force is needed to have the same amount of sag. If you get a replacement shock, make sure they sell you the correct size spring, as this will let your shock work in the middle of its range, not at an extreme. You'll have to weigh yourself with all your gear on for them to know what the right size is. As for the forks, many monsters don't have adjustable forks, so the fork needs to be opened up and stiffer or lighter springs need to be used. if your forks are adjustable, there is a medium size nut on the top of the fork that is used to preload the fork spring.

Compression - this refers to the speed with which the shock compresses. This is adjusted with a small screw on the shock, which regulates the size of the holes that shock fluid goes through as the piston is compressed. Too hard compression and the shock will feel hard and the road very bumpy. Too soft and it'll feel like you're bouncing on a big rubber ball. Again, on the forks, if they aren't adjustable, there is little you can do except have a different weight fork oil and/or aftermarket "valves" installed.

Rebound - when the fork compresses, it needs to come back out to be ready for the next bump. This is also adjusted with a screw on the shock. If there is too much rebound it'll feel like you're on a pogo stick, and the tire may actually lose contact with the road after a bump. Too little rebound means the shock takes to long to come back to starting position, and the shock will "pack" with successive bumps, losing the ability to absorb successive bumps. Again, with non-adjustable forks, it is a matter of replacing oil and internals.

Suspension is one of the most important, but most misunderstood aspects of motorcycling. If you are a Ducati owner, which you most likely are if you are reading this, you do have a distinct advantage because your suspension components as delivered are very good. But in true Ducati fashion, are set up horribly. The following instructions are intended to provide you with a motorcycle that performs correctly when pushed hard. This may be at the track or your favorite back road. But I have found that a good track set up works very well while commuting or going to get milk at the store too. Most “race” bikes are actually a lot plusher than their street ridden brothers.

Cheating - Everything about setting up suspension can be cheated, or if you prefer compromised. Let’s say for example I say you need so-and-so spring for your shock in step one, but you will not be purchasing one for some time. This does not mean that you should not continue with the steps. You should. During the set up process there will be opportunities to “cheat”. But when all the steps are completed, you will not be 100% set up. But you may be 85% set up, and that is a lot better than your bike probably is right now. When you do make the purchase of the right spring, all you will need to do is have it installed, do a bit of tweaking and you will be on the cusp of greatness.

Spending Money - I am about to tell you something that you will be delighted to hear at first, but then question because it is most likely contradictory to what you have been told about suspensions and motorcycles. YOU DO NOT NEED TO SPEND A TON OF MONEY TO GO FAST! Believe it or not but it is a fact. Lets face it, we will never be THAT fast. All track day riders and most amateur racers will never be able to override the stock components on a Ducati Superbike. For example I have gone around my home track (Grattan Raceway) within 4.5 seconds of the lap record on a stock 999 with good tires, and there are a lot people that could go faster! That is outstanding performance for off the showroom floor components with a little tweaking. That being said, getting top line suspension work or components will make you go faster simply because the bike will be more composed and therefore you will be more comfortable. So spend the money if you want, it won't hurt (as long as you are getting good work or components). But don't be upset when Joe Racer smokes by you sideways on stock components.

I will keep this as basic as possible; I could write a novel on all the ins and outs of setting up a suspension. The most important thing to do while learning to set up a bike is always ask “why”. When you can figure out “why” this change did that and “why” that change did this, you will develop an internal data base of possible outcomes. So the first lesson is to always ask “why”. You can not blindly start clicking clickers and hope for a good set up. You must “test”, that means taking notes, small steps and thinking about every move you make. Secondly your ultimate goal is to get the “feel”. You will develop a sense of what is good and what is bad, but it will take time.

The outline for setting up your suspension is as follows:
Geometry - The framework for a good set up. Geometry is the “hard” setting that you will be putting into your bike. Geometry is the angles and or heights that you plug into your bike. Geometry is 75% of your ideal set up. There are specific geometry settings in either the 749/999 or the 748/916/996/998 sections.

Sag or Preload - Sag can be looked at one of two ways, #1 as a secondary geometry setting. But unlike geometry which is a “hard” setting, sag is dictated by spring rate. This must be picked and set up correctly. #2 as a means of confirming you have the correct spring rate for your application. The process of setting sag will “tell you” if you have the correct springs. Springs are the foundation of all suspension action. Sag or pre-load will be adjusted with the preload adjusters

Compression - compression dampening is an adjustment to the valving that will increase or decrease the speed at which the suspension component will compress. The compression circuits job is to “control” the spring when the wheel hits a bump, you get on the brakes, land a wheelie, etc.

Rebound - rebound is extremely important, rebound has a huge effect on how comfortable you feel on your bike. The rebound circuit controls the suspension as it is trying to spring back after the wheel has hit a bump, after you let off the brakes, etc. The first thing you need to know to get your head around the concept of rebound is to never ever refer to it has hard or soft. From this point on you are only allowed to refer to rebound settings as fast or slow. Do not forget this!

1. Setting Sag: Forks
•   Back out the compression and rebound adjusters all the way out counter clockwise. You are doing this to free up the components so it's easier to set the sag. You may want to write them down.
•   One of your friends (we will call him Bob) and you should grab the handlebars and lift the front of the motorcycle until the wheel is not touching the floor. Your second friend (we will call him Neil) will measure the distance from the bottom of the fork seal to the bottom of the slider where it meets the fork foot. Have Neil do all of your measuring for consistency. The distance between the two points will most likely be 124mm. Write this measurement down, it is your “unloaded” measurement (measurement A). You will be calculating all of your sag measurements off of this number…so get it right. It's supposed to be a constant, not a variable.
•   With Bob holding the motorcycle by the tail so you do not fall over, mount the bike and assume the riding position (head down feet on the pegs). Bounce up and down a few times to settle the suspension.
•   Have Neil pull up on the triple clamps a bit and let them go. Take a measurement (measurement B).
•   Next have Neil push down on the triple clamps and then let it go. Take a fork measurement (measurement C).
•   The reason you are taking the push down and pull up measurements is to calculate actual sag. All forks have stiction, which is the friction on the fork slider. The stiction will stop the forks short of their actual sag, so you need to account for this. By taking two measurements (one pushing, one pulling) and averaging them you will get your actual sag point. Bikes with the pretty gold sliders will have less stiction than the non treated ones…that's the point of the gold (sorry to disappoint all you pimps out there).
•   To calculate rider sag use this formula A- [(B+C)/2]:  add B and C together, divide by two and then subtract from A.
•   If your rider sag is less than 35mm, remove fork preload by turning the preload adjuster counterclockwise. If your rider sag is more than 35mm, add preload by turning the preload adjuster clockwise. Adjust and re-measure until you have 35mm of rider sag.

2. Setting Sag: Shock
•   Install your ride height tool in the frame. If you do not have a ride height tool place a small piece of tape directly above the rear axle on the tail and use this as your upper measuring reference point. You and Bob will then lift the back of the motorcycle, by the footpegs or front of the subframe where it bolts to the frame until the rear wheel is off of the ground. Do not lift by the rear of the subframe, you will flex the subframe and get an incorrect measurement. Measure the distance between the mark on the tail and the top of the axle nut. Write the measurement down, it is your rear “unloaded” measurement (measurement D). You will be calculating all of your sag measurements off of this number…so get it right. It's supposed to be a constant, not a variable.
•   With Bob holding the motorcycle by the front fairing so you do not fall over, mount the bike and assume the riding position (head down feet on the pegs). Bounce up and down a few times to settle the suspension.
•   Have Neil pull up on the subframe (where it mounts to the frame) a bit and let it go. Take a measurement (measurement E).
•   Next have Neil push down on the seat and then let it go. Take a measurement (measurement F).
•   The reason you are taking the push down and pull up measurements is to calculate actual sag. All shocks have stiction, which is the friction on the shock shaft. The stiction will stop the shock short of their actual sag, so you need to account for this. By taking two measurements (one pushing, one pulling) and averaging them you will get your actual sag point. Shocks will have less stiction than forks though.
•   To calculate rider sag use this formula D- [(E+F)/2]: add E and F together, divide by two and then subtract D
•   If your rider sag is less than 30mm, remove shock preload by turning the preload adjuster rings (the two rings that are holding the spring in, the best way to adjust them is with a drift and a hammer) counter clockwise (as if you were looking down from the top of the shock). If you rider sag is more than 30mm, add preload by turning the preload rings clockwise. Adjust and re-measure until you have 30mm of rider sag.

[DucHead]

3. Setting Compression: Forks
•   Well, this is going to sound a bit vague, but there is no really good way to set the compression in the pits on your forks without having a ton of experience with it. But we can ballpark it and then test for it once you are riding. Most Ducatis come with very stiff compression circuits, so this makes it pretty easy to find a starting point.
•   Run the compression adjuster full soft (pretend you are laying on your back looking up at the bottom of the fork and turn the adjuster counterclockwise, or out, to soften the compression). The adjuster is located on the bottom, or to be more specific in the bottom of the fork foot. You will need to run a standard screwdriver from the bottom of the fork foot up through the axle. It's kind of a PITA but if you have the right size screwdriver it's not too bad.

4. Setting Rebound: Forks
•   Your rebound adjuster (located on the top of the fork, adjust with a standard screwdriver) should be all the way out from when you adjusted your sag. If it is not run the adjuster all the way out counterclockwise. I think this will be a good time to explain how to correctly “view” the rebound circuit. Rebound is never “hard” or “soft”. It will only be refereed to as “fast” or “slow” from now on. This will help you understand what the rebound is doing. Spinning the adjuster out or counterclockwise will make the forks rebound faster. Spinning the rebound adjuster in or clockwise will make them slower.
•   So here you are with your forks as “fast” as they will go. To get an idea of what I am taking about bounce the front end of the bike by holding on to the handlebars, applying the front brake and quickly pushing the front end of the bike down. When the forks rebound you need to get neutral on the bars. Do not pull up on the bars or put weight on them when it is trying to rebound. All you really want to do is provide enough input to keep the bike from falling over. Practice this a few thousand times until you get it just right. What you are looking for is a situation where the forks can rebound with a minimum of input from you.
•   Now that you are the “master of the bounce” you can start tuning the forks. With the rebound adjuster full fast bounce the front end. What happened? Did it rebound back really fast and take a couple of seconds to settle? Now run the rebound adjuster all the way in clockwise (do not run it in hard you will seat the needle and cause all sorts of problems). Bounce the front end again. What happened? Did it take for ever for the forks to rebound back to full extension? Sure did. You have just seen the difference between fast and slow rebound in a set of forks.
•   Run the rebound all the way out (fast) on the forks again. To set the rebound you need to start from all the way fast.
•   Bounce the front end; see how it rebounds back past the sag point (the point where the bike sits on its own weight) and then settles down? This is not what you want. You want the forks to rebound right up to the sag point without going past and settling. But here is the catch; you want them to rebound to the sag point without being too slow. The method for finding the right spot is to bounce the front end, check, add a click, bounce the front end, check...until you get the front end too just come up to the sag point without going past. When you have the front end rebounding right to the sag point, speed it up one click just to check your work. If speeding it up the one click lets the forks rebound past the sag point just a touch you had it right. Add back the click you took out and you are done. Above all you are looking for the rebound circuit to control the springs in the forks. You will know it when you see it.

5. Setting Compression: Shock
•   Once you have set the compression and rebound on the forks you can do the shock. Above all you are looking for a balance from front to rear, so what you are going to do is use the setting on the front as a gage for setting up the rear.
•   Get the bike off the stands and stand next to it with your hands on the gas cap. Have a friend stand back from the bike so they can observe the entire bike front and rear.
•   Push down sharply on the gas cap with both hands as hard as you can and let the bike rebound with no interference (like when you did the forks but this is for the whole bike). You may want someone else standing there to catch the bike when you throw it at them by mistake. It will take you a few tries to get this right.
•   What you are looking for is the front and rear of the bike to go up and down at the same time. You just set up the front so what you want to do is even up the rear. If the rear is going down slower than the front, then remove some compression from the shock by turning the compression adjuster counterclockwise. Turn it clockwise to add more compression if the shock is going down faster than the front. The adjuster is on the remote reservoir on the shock. On Showa shocks it is a standard screwdriver on Ohlins it is a black knob you turn with your fingers.
•   You are done adjusting the compression on the shock when the front and rear are going down at the same rate/time.

6. Setting Rebound: Shock
•   Push down on the gas cap and have your friend watch the bike again.
•   You are looking for the rear to rebound at the same rate as the front.
•   If it is to fast slow the shocks rebound down by turning the rebound adjuster clockwise. The rebound adjuster is located at the base of the shock shaft. On Showa shocks it is a standard screwdriver and on Ohlins shocks it is a black knob that goes around the shock shaft. When adjusting the Ohlins shock make sure you are pretending you are on your back looking up at the base of the shock to make sure you get the directions right (Clockwise and counterclockwise)

7. Checking Your Work
•   Checking your work is pretty simple. Get the bike up off the stands again and push on the gas cap with a friend watching. The bike should compress and rebound evenly front and rear. If it does you are ready to ride. If not go back and make the proper adjustments.

Tuning - Ahh tuning, here are a few simple steps to getting you bike dialed in that next level. At this point I need to tell you that you are pretty much on your own. There is a lot of “feel” involved in getting your bike set up for you, and it's impossible for me to get it down on paper. The biggest thing I can tell you is do not be afraid to think outside the box. If you start clicking this and clicking that and the bike works perfectly you have a good set up for you. Don't be worried when you bounce your bike and the front and rear are not even. The “even” set up is a great starting point, not the rule of thumb. What follows are a few steps I use to tune my forks in and then a lot of “if its doing this, do that” bullets. Keep these things in mind:
•   Have fun
•   Record your changes
•   Make one change at a time
•   If you make a change and do not understand what it did, don't do another until you do.
•   Think outside the box, there is no right
•   Test, test, test, test

Tuning Forks
•   Put a zip tie around one of the fork sliders. Go ride the bike…. hard . If you do not bottom the zip tie remove one turn of preload, go ride. Repeat as necessary. It does not matter if you end up with 40mm of sag in the front. You need to use all of your travel.
•   If your forks are bottoming out the first time you ride it, add some compression. You never want to add preload and have less than 35mm of sag.
•   If when you grab the brakes the front end dives dramatically and upsets the rear end, add some compression to the forks. But keep in mind if you are mashing the brakes on you will upset any set of forks, so brake smoothly.
•   If you end up adding a bunch of compression make sure you bounce the bike to check the balance from front to rear. It can be a bit out of balance but not a ton.
•   If the forks take a second to settle after you let of the brakes and you are tipping into a turn, slow the rebound down 1 click.

Tuning the shock
•   If the rear end does the Ben Bostrom death weave while on the brakes speed up the rebound.
•   If the rear end goes grip slide, grip slide. Add compression

Checking if you have the correct springs
•   Once you have set the sag on your bike you can check if you have the correct springs.
•   Measure the free sag of the front and rear of the bike. Free sag is the sag the bike has under its own weight, without you on it. Your free sag should be 15-30% of the rider sag number. For example if your shock sag is 30mm with you on it you should have 5-10mm of free sag. If you have lets say 0mm of free sag your spring is too soft. If you have 15mm of free sag your spring is too stiff. Same goes for the forks.

Random thoughts
•   If you use something like a subframe or tail as a measuring point for sag make sure that it does not flex or move, this will screw up your measurements.
•   Check your chain tension. I have seen a lot of bikes where the chain was so tight that it limited the rear shocks travel. Obviously this is a big problem for the suspension but the biggest problem is the output bearing on your bike will get destroyed. So how do you know if your chain is adjusted correctly you ask? Well a loose chain is a happy chain, if it is not falling off its tight enough. We run ours sloppy loose.

[RodeoClown]

Can this be cross referenced to the How-To section? This is great but hard to find at times?