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Motorcycle Suspension Setup 101

187K views 199 replies 71 participants last post by  R6Ruckus 
#1 · (Edited by Moderator)
I've been riding for almost 30 years, and I've learned a little about the sport and the machines. But somehow, I've developed an affinity for the suspension issues of the machines we ride. Somehow I think it's because so many people focus on power, and so many people are not keen on working on handling it.

In the following series of posts, I hope to get some information that can help with a basic setup. As the thread continues, I hope we can discuss chassis setup matters and learn from each other.

I've read several books, watched many videos, and searched through many websites and forum posts for this information, so I hope it helps someone.

I'm breaking it down into different sections. Hopefully, if you are tuning your suspension, you will follow the thread and get somewhere you haven't been. Remember, if the rest were meant to be set one way, the factory would not have made it adjustable.

In the world of motorcycling, we encounter many changing conditions, and we modify our machines to accommodate them and customize our machines to suit individual tastes. But one of the areas typically left unchecked is the suspension. And when we do address our break, many have the tendency to go from one extreme to the other by purchasing mega-buck parts that we may not necessarily need. Often, a basic setup with the stock or mildly modified details is all we need.

In this thread, I'd like to address some of the basics of suspension setup. As you will find, there is no one set adjustment for everyone to use, and it's fine-tuning the component setup to accommodate the specifics of an individual pilot on a given motorcycle. I hope you'll learn something from the following and better understand how to adjust your suspension to provide yourself with the best handling and comfort possible.
 
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#2 ·
Suspension setup basics:
  • - Static (Rider) Sag: The amount of suspension travel used by the combined weight of the machine and rider, measured from topped out.
  • - Free Sag: The amount of suspension travel used by the weight of the machine alone, again, measured from topped out.
  • - Damping: Damping is simply the components ability to dampen the oscillating energies that the suspension will be exposed to.
  • - Compression: The damping that controls the downward stroke of the suspension. At the bottom of the forks and the top of the shock (typically).
  • - Rebound: The damping that controls the upward (return) stroke of the suspension. At the top of the forks and the bottom of the shock absorber (typically).
  • - Stiction: This is the drag placed on suspension components due to friction, drag, linkage and other moving parts of the suspension. DO NOT be surprised if this is a large amount as in the Kayaba forks used in the YZF-R1 and ZX10R. This is normal, and these forks are capable of performing extremely well.
  • - Rake: the angle of the steering head relative to a line perpendicular to the ground.
  • - Trail: the distance from the point axis intersects with the ground to the tires contact patch directly below the axle.
Tools needed - Generally, simple hand tools that come with the motorcycles tool kit are mostly all that are needed, but as with anything, better tools will make the job go smoothly, and include:
  • - Flat screwdriver
  • - Various box end wrenches (preferably six point)
  • - Various sockets (preferably six point)
  • - Spanner wrench for rear shock preload
  • - Tape measure or ruler (metric)
  • - Zip ties
  • - Stands (the Baxley type is GREAT for this)
  • - Assistant(s)
 
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#3 ·
Part I Setting Sag

The first step to setting any suspension is to set the sag. Simply stated, sag is the distance the spring compresses from fully topped out. Race Tech and others have information on the different methods used to measure this on their websites etc, but I'm going to stick with explaining the method used by Race Tech due to the high amount of stiction found in the Kayaba forks.

Rear: When taking your measurements at the rear of the machine, you will need to measure from the center of the axle to a point directly above the axle.

Step 1:
You will need to fully extend the rear suspension. You can do this with jacks, some really strong friends to dead lift the bike, or carefully pull it over onto the kickstand. Just remember the R1 has an aluminum kickstand, and it can snap pretty easily. Measure from the axle to the point directly above the axle on the frame.

This measurement is L1.

Step 2:
With an extra person holding the bike balanced from the front, have the rider get on the machine in all normal riding gear and get into a the normal position they ride in. Yes, it does make a small difference. Firmly push down on the rear of the machine about 1 inch and VERY SLOWLY release the pressure. Again, measure from the axle to the point directly above on the frame.

This measurement is L2.

Step 3:
Next, lift up on the rear of the machine about 1 inch, and again VERY SLOWLY let the rear end down. Again, measure from the axle to the point directly above on the frame.

This measurement is L3.

Step 4:
Because of stiction, you should have a difference between L2 and L3. So the average of the two would be where the static sag is. To calculate do the following:

L1 - ((L2+L3) / 2)

Or in English, add L2 and L3 together, divide by two, then subtract from L1.

This number is your sag and should be between 25 - 30 mm (track) and 30 - 35 mm (street).

Once you have the measurement made, you will likely need to adjust to get to these numbers. If the measured sag is too large, you will need to increase the preload on the fork. Too small, you will need to decrease the preload.

After you have the static (rider) sag set to a good starting point, you can use the same method to determine the amount of free sag available. Record this number in your notebook or settings sheet. If your springs are in the correct weight range, this should be from 0-5 mm for street and road race sportbikes.

Front:
There are a couple of ways to do this, but I'm going to explain the Race Tech method. Thing to note about measuring the front is there will be a minor difference in measuring conventional and inverted cartridge forks. Aside from that, it's all the same. I like to put a zip tie on a fork tube to help with measuring, and as an indicator of how much total travel I'm using of the suspension.

Step 1: Using assistants or a front stand that lifts from the triple clamp, fully extend the front suspension. Again, the kickstand can be used CAREFULLY. Measure from the dust seal to the bottom of the triple clamp (conventional) or from the dust seal to where the inner fork tube meets the lower casting (inverted cartridge).
This measurement is L1.

Step 2: Using an assistant to steady the rear of the machine, have the rider get on the machine in all normal riding gear and get into the normal position they ride in. Firmly push down on the front of the machine about 1 inch and VERY SLOWLY release the pressure. Again, measure from the dust seal to the bottom of the triple clamp (conventional) or from the dust seal to where the inner fork tube meets the lower casting (inverted cartridge).
This measurement is L2.

Step 3: With the rider still on the machine lift up on the front end about 1 inch and VERY SLOWLY release the pressure. Again, measure from the dust seal to the bottom of the triple clamp (conventional) or from the dust seal to where the inner fork tube meets the lower casting (inverted cartridge).
This measurement is L3.

Step 4: Because of stiction, you should have a difference between L2 and L3. So the average of the two would be where the static sag is. To calculate do the following:

L1 - ((L2+L3) / 2)

Or in English, add L2 and L3 together, divide by two, then subtract from L1.

This number is your sag and should be between 25 and 30 mm (track) and 30 and 35 mm (street).

Once you have the measurement made, you will likely need to adjust to get to these numbers. If the measured sag is too large, you will need to increase the preload on the fork. Too small, you will need to decrease the preload.

Do NOT be surprised by large differences between L2 and L3. There is notably a large amount of stiction in the Kayaba forks, and this is normal.

If you are able to get to the baseline numbers listed above for the riding you will do, you are at a good starting point. If not, you will likely need to re-spring the motorcycle. There are several options to choose from that can be less expensive than ordering new forks or shocks (significantly less in most cases).

After you have the static (rider) sag set to a good starting point, you can use the same method to determine the amount of free sag available. Record this number in your notebook or settings sheet. If your springs are in the correct weight range, this should be from 0-5 mm for street and road race sportbikes.

Once you have gotten the sag adjusted to your preference and recorded your results you will be ready to move on to the next part.
 
#4 · (Edited)
Part II Setting Rebound

Now that your sag is set for your weight, and you have a decent basis for further adjustments, it's time to discuss the most important damping setting. The rebound damping on your suspension ensures the wheel at the end of the suspension is able to stay in contact with the road without excessive oscillation.

The goal here will be to be able to push downward, very firmly and quickly on the suspension and allow it to rebound up. The suspension should smoothly reach the top of its travel and settle, without beginning a second down stroke.

Before setting a starting point it's good to be sure that your valving can accommodate what you are doing. To do this you will "bounce" the machine firmly down and allow it to return. I do this with the rebound adjuster full out, and then full in, to determine how adjustable it is. Then adjusting your damping whether it is rebound or compression, it is VERY IMPORTANT that you take care not to force the adjusting screws. Forcing the screws will likely damage the components and require replacement. Lightly seat the screws in each direction. With the rebound full open, the machine will bounce several times before dissipating the energy of the bounce. Conversely, with the rebound fully closed the machine will bounce partially back up, and either stop or "creep" to the top of the stroke. If it behaves other than this, your components may need servicing or replacement parts.

Once you know the total number of clicks from full open to full closed, you can start at about 1/3 of the clicks out from full stiff to start testing.

With the rebound adjustment at about 1/3 of the clicks out from full stiff, hold the front brake and push down on the bars firmly and quickly. While doing this it?s good to watch the nose fairing and the background to see movement. What you want here is to have the front return to the top of the travel range and settle smoothly. It should not begin a second down stroke nor "creep" to the top of it's range. If it is too fast and begins a second bounce, add a few clicks of rebound damping (clockwise, closing the valve). If it creeps or is slow to get to the top, remove a few clicks (counter clockwise, opening the valve).

The rebound damping is especially important in that it will help control the wheel?s ability to stay in contact with the pavement while traveling over bumps. Too much rebound damping and the wheel may lose contact with the pavement over bumps. Too little, and the front end will be constantly oscillating, sort of like a pogo stick.

With all things considered, the rebound damping is arguably the most important suspension setting. You will always want to recheck the rebound damping as conditions change.
 
#5 ·
Part III Setting Compression (low speed)

With the sag and rebound damping set, we are ready to begin addressing the low speed compression damping. More and more suspension components are equipped with high and low speed compression adjustments. The terms "high" and "low" DO NOT refer to the speed that you are traveling. They refer to suspension travel speeds. The primary adjustment will be to the low speed compression adjusters. The high speed compression adjusters will help you adjust for sharp edge type imperfections. While it may seem possible to set the compression damping similar to how we set the rebound, it isn't at all practical to do so. Because of factors such as unsprung weight, pavement surface, ambient temperatures etc, you will need to choose a starting point and adjust from there.

While adjusting the compression settings it's a good idea to determine how much damping you have available. To do this you can adjust the compression full stiff, by turning the screws full clockwise. Be sure to do so until they are LIGHTLY seated, and count the clicks in. If you push firmly on the suspension at this point you should see that the suspension is very stiff, and you are not able to go through much travel. Then you can adjust the compression full soft, by turning the screws full counter (anti) clockwise, counting the total number of clicks. Again be sure to do so until they are LIGHTLY seated. Pushing on the suspension at this point you will see much more travel and a plush feel. Return the screws to their original settings, the manufacturer suggested starting point, or about 1/3 the total number of clicks out from full stiff. Record this setting on your notepad or data sheet.

The majority of your compression tuning will be done from on track or on the road observations, so you will need to keep track of how the bike feels over single and repeated bumps or rough pavement. Remember the zip tie? Now is one of the times it will come in handy. After you run a session or stretch of road, you will look at the zip tie to see how much suspension travel you've used. Typically there should be between 5 - 15 mm of travel left. This will vary from manufacturer to manufacturer as many forks will typically bottom out internally before the zip tie hits bottom. Keep note of how far the zip tie is from the stops. You can adjust the total travel by adjusting the low speed compression damping.

I've heard of tuners putting a small zip tie on the shock shaft as well, although I've never done it or discussed it with anyone. But the principle is the same.

Again, your notebook is your best tool, and the more information you keep track of, the easier it will become to make positive adjustments.
 
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#136 ·
Typically there should be between 5 - 15 mm of travel left. This will vary from manufacturer to manufacturer as many forks will typically bottom out internally before the zip tie hits bottom. Keep note of how far the zip tie is from the stops.
Great thread , learning a lot - kudos to DanQ !! On a stock '06 R6R , does anyone know how far the dust seal is from the axel shaft at mechanical bottom out ? Is it 5mm or 25mm ? Checked the forums, haven't found a concrete number on this. Would be safer for all of us to have a figure in mind in advance, rather than finding out during an emergency braking that the mechanical bottom was much closer than suspected.. Any thoughts?
 
#6 ·
Part IV Geometry: Ride height, rake, and trail.

As we make adjustments to the suspension, we have been ultimately affecting the chassis geometry. While the steering head is welded in place, setting the rake at a constant, it is possible to change this angle slightly via suspension adjustments/motion. For instance, raising the rear ride height can effectively make the rake angle more steep. Also, lowering the front by pulling the fork tubes up in the triple clamps will not only change the rake angle, but it will decrease the amount of trail. Generally speaking, the change in trail will be approximately 1 mm for every 4 mm of ride height change.

Increased rake will allow more relaxed steering and greater straight line stability. Conversely, decreasing the rake will provide quicker steering, and less stability in a straight line.

Increasing and decreasing trail is a little bit less subtle, and large changes, as with everything, should be avoided.

As the discussion continues, we may discuss other factors as necessary, but if you've read to this point, you have the basics.
 
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#7 ·
Part V Balance

Although the topic of balance comes up at different points in discussion by different tuners, I've chosen to address it at the end. While we've been going through the suspension components making various adjustments, we've been doing so to either the front or the rear suspension. In balancing the chassis, we will want to be sure that the front and rear are moving at roughly the same rates of travel. This will help us to ensure the front and the rear will respond similarly to the same pavement inputs. And that is what it will take to help keep the chassis geometry as consistent as possible.

To check the balance of the motorcycle, using either a Baxley type front wheel stand/chock or an assistant to help keep the motorcycle upright, you will want to push down on both ends of the suspension with even force. You should push from about the gas cap (where your sternum would be in a race tuck) and the rear portion of the rider's seat. What you will want to see during this is that the forks and shock descend and rise at the same rate. If the front or rear descends quickly, add a click or two compression damping to the component that is quicker. Conversely you can remove a click or two to the opposite end making that end faster. In either case you will want to get the front and rear moving at the same rate.

Once that is done, you will want to push down on both ends again, this time observing the rate of rise. If the front or the rear rises too quickly you will want to add rebound damping to the faster end, or remove some rebound damping from the slower end. Again, the goal here is to attain a rising rate that is similar front and rear.
 
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#8 ·
Handling is arguably one of the most important aspects of motorcycling. The entire time you are on the motorcycle, you are using it's handling capabilities. Understanding the principles of chassis setup will better equip you to maximize the ability to tune your motorcycle for the conditions you ride in and your riding style.

Thanks for reading. Please provide feedback or impressions you may have as well as any questions we can help one another with.

Good sources for further information

While preparing this thread I have gone through pages and hours of information from reputable sources. Most notable for me have been:

-Sportbike Suspension Tuning by Andrew Trevitt - This book has been the most helpful tool for me in understanding suspension setup and characteristics. I recommend Andrew Trevitt's book to anyone wanting to learn more about sport bike suspension setup and tuning.

-Twiddling the Knobs and Introduction to Suspension with Dave Moss from Dave Moss of Catalyst Reaction. These DVDs are available from Catalyst Reaction and are great for in depth explanations. The case studies are superb, and well, the way Dave Moss says "chassis" is just cool.


-Tuning Guide on Catalyst Reaction's website - http://www.feelthetrack.com/ - There are several articles done by Dave Moss on suspension tuning, as well as some outstanding data sheets for recording suspension settings for track days or race setups

- Motorcycle Trackday Handbookby Kent Larson, Pat Hahn, Jason Bishop and Max McAllister. This book is an excellent read for those planning track days, and contains a very good section on suspension setup.

-Suspension Tuning Guide by Dave Hodges. This is a useful guide in quickly troubleshooting motorcycle suspension that I've used a lot over the years.

- And of course, the FAQ and other information by Paul Thede of Race Tech at www.racetech.com. Not only do I personally prefer the parts offered by Race Tech, I frequent the website for troubleshooting and information. While preparing this thread I've noticed that many authors/tuners reference Paul Thede's methods, such as the sag setup exclusively.

Handling is arguably one of the most important aspects of motorcycling. The entire time you are on the motorcycle, you are using it's handling capabilities. Understanding the principles of chassis setup will better equip you to maximize the ability to tune your motorcycle for the conditions you ride in.

Thanks for reading. Please provide feedback or impressions you may have as well as any questions we can help one another with.
 
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#9 ·
good writeup
 
#13 ·
Thanks for the comments guys.

As I post additional information to clarify on the R1-Forum, I'll post it here as well.
 
#14 ·
Possibly add a note that you should take the bike for a ride before you work on suspension, as the oil in forks/shocks is greatly effected by temperature, and should be warmed up a bit before making any useful adjustments.

This is the first time I've seen someone write up a suspension how-to that is actually understandable. I'll be using your guide to work on my base suspension setup after work tonight.



STICKY THIS PLEASE!
 
#15 ·
As the thread goes on in both Forums, I will be adding information. The main thing I wanted to do was get it out in a way that could be followed in stages (i.e. set sag, ride, set rebound, ride, etc). And to give a clear starting point to get everyone through the basics. In a while we will hopefully discuss subtle geometry changes, addressing specific issues on the street or track, squat/anti-squat and anything else that comes up.

We are also working on some pictures and videos to assist.

While a very good solution is to take it to a suspension guy, it may be better to have a basic understanding of what affects what, so you can clearly convey to the suspension guy what is happening, as well as what it may take to correct it.

Thanks for the read, and the comments. I've stickied this per your request.
 
#18 ·
looks like some awesome info! i'll be reading it soon and hope to be able to contribute my own findings as the season progresses. thanks dan!
Thanks for the read and feedback guys. I'm looking forward to some one on one training with a suspension pro, and I'll be adding what I learn from him as well as more in depth tuning information.
 
#22 ·
#25 ·
Me and a friend finally did ours today and wow, the front sag was WAAAYYYY off!!! I swear the bike was set up for a 130 lbs girl... I haven't had the chance to do any really aggressive riding but i swear I can feel a difference.. My friend did most all the research and I basically just let him show me what to do, but after reading through your write-up I'm very confident he knew what he was talking about... I only wish I had done this like a year ago!! After just riding casually I swear the bike feels more stuck to the ground and the front doesn't dive nearly as much as it used to.. Before today I had kinda experimented with the compression and rebound settings, but I think getting the sag right was extremely important.. Maybe it's all in my head, but I know for sure that it at least isn't diving as much anymore.. GREAT write-up, after reading through it I feel even better about finally taking the time to set my bike up, I'm stoked to get more seat time with it all custom fitted!! Everyone should definitely do this!
 
#26 ·
Thanks for the read, and the feedback.

I wrote this in what I feel is order of importance. It's also the order I do my suspension setups in, and having watched a few others, the same order as they do theirs.

Hopefully soon I'll be posting some troubleshooting information, followed by service and upgrades.
 
#27 ·
nice write up! very noticeable difference when the bike is set up properly. i did mine about a year ago, and set up a few other people. they noticed it also right away. will be needing to do again soon since i have put alot of miles on and bike was sitting through deployment. will follow your guide to see if i missed anything in my previous setup. again, well done!
 
#29 ·
Nothing makes my eyes water more than a write up that normal people and engineers can understand. I say them in that order because these kinds of things are usual watered down so the everyday joe can understand what's going on. But in doing so they lose the accuracy afforded by using those long and confusing technical words and you'll find guys like me (BS Engineering and Business) pulling their hairs out in frustration.

Then you'll get the other side with the guys that can't speak plain English. I went to school with them and if it wasn't so detrimental to getting shit done I'd have laughed my ass off every time I saw one blumber through a presentation.

Great write up. Hits the middle ground perfectly and does a great job with descriptions and instruction. Now if my recently graduated @$$ wasn't so broke, I'd go do the work right now. Need to get the tools first. =\

Regardless.. . A+ Dan. What's your background in anyways?
 
#30 ·
Thanks for the feedback.

I'm a retired US Marine and I work in computer systems. But I became extremely interested in chassis and suspension, so I try to learn from every means possible. Being broke helps because it forces me to do things myself.

In the near future I'm planning to add troubleshooting and maintenance to this thread. So hopefully it will become worth more to everyone.
 
#34 ·
Hi Dan. Nice write up.

I have a couple comments/questions.

A little back ground. Last yr I got ahold of a guy on here (cant remember his name) and he gave me a base setup that he was putting on the 06+r6's at the track he rides at. I put it on and wow, the bike was great from there. The only problem I had was it felt unstable when really tipped over in a turn. I lowered the front ride hight (slid the forks up in the clamp) about 4mm and it was perfect. It was smooth as glass when leaned over hard.
Whats the down side to that adjustment? It does take more effort to change directions but its soo smooth now.

I did have to take a few clicks of compression damping out of the front and rear cause of the harshness around town. Took the bike to the track for the first time last yr and it was awsome all day. Im new to sportbikes so Im not really sure what a dialed bike is supposta feel like but, I could feel the front and rear tires all day long. Well, after a day of hammering on my bike the only thing I could think of that needs work (besides me) was the bike didnt want to transition onpower. Even 1/3 throttle made it push the front tire. I know my form needs some work and could throw a little more body up there but, anything in the suspention that could help??

Thanks
DK
 
#35 ·
Thanks for the read, feedback and questions.

What type of rear shock do you have? And what are your sag numbers? Reason I ask is typically pulling the forks through the triples to lower the front quickens the steering. and it can take less effort to go into a turn, but possible a little effort to exit (get the bike to return to upright).

It's interesting that you ask about a downside the the adjustment you made. It's obvious you understand suspension a little more than you may think. There are few absolutes in suspension tuning. The same end can often be achieved in more ways than one very often. For example: you wanted to quicken your steering so you lowered the front by pulling the forks through the tubes. This will lower the front end, changing the rake angle slightly as well as decreasing the trail minutely (about 1mm for every 4mm of drop). This same offset bias could be achieved by increasing the front sag a few mm (watching for bottoming). Or, increasing the rear ride height or even sag a few mm. All the methods would have different overall affects on the chassis.

For an R6 I prefer to try to use the fork height within the tubes as a last means of adjustment. The R6 is pretty easily capable of dragging hard parts, so bringing it closer to the ground isn't something I like to do. But opinions vary. I know several that do it routinely with excellent results.

As for the push you are describing, could you be more descriptive? I am still working on my troubleshooting vocabulary. At what point in the corner are you talking? Entrance, mid corner, or exit?
 
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