Tips for Establishing the Baseline Settings
on a Dirt Bike
This article on establishing the baseline settings of a dirt bike is primarily targeted towards those with dirt bikes built from about 1986 to present, (since these have the greatest amount of adjustability), so if your steed was built after 1986 (which applies to most people reading this), you're in luck as you will be getting hooked up with the skinny on pretty much everything you need to know to get your dirt bike back to a baseline setting and handling better, and if you ride a vintage style bike there is some info here that should help you as well.
You'll find this article especially helpful If you've been trying to get a motocross dirt bike's suspension and handling characteristics dialed in, and you've been twisting clickers, changing fork height and messing with the sag so much so that you really don't know where everything is set at presently (or you just don't want to admit it), now would be a good time to start over and get all your baseline settings established.
Also, The manufacturers of motorcycles and suspension components go through extensive testing to establish a baseline setting for their motorcycles and components so they will perform and handle as optimally as possible for the widest range of riders, and this really is an excellent place to begin. Furthermore... After following the steps in this article, you're probably going to be so impressed with the way your dirt bike handles, that you're likely going to think you should start your own suspension outfit at the local track, but just do them and me a favor, and tell your buddies about this page as it's a lot easier for everyone that way.
Get Your
Free Setup Logs
If you're going to be making changes to a dirt bike's suspension, chassis or engine in order to fine tune the performance of the motorcycle, be sure to record the changes as they are made on either the:
Advanced Setup Log
or
Basic Setup Log,
both of which are free and available for use or download, and distribution to all your friends and riding buddies.
Just to Know Before Getting Started...
This article will help you with establishing a baseline setting for your suspension and chassis that you can work off of, by starting with the basics, which are commonly referred to as your baseline settings and this entails your suspension's compression clickers, rebound clickers, spring sag, fork tube height (fork overlap) and that, along with having all of the other available motorcycle controls dialed in can have a remarkable difference on the handling of a motorcycle, afterall, having the dirt bike setup properly for an individual rider is one of the most important things someone can do to enhance their experience while on a motocross track, off-road course, weekend on the trails or when attacking the freestyle motocross (FMX) ramps at your favorite compound.Also, It is all too often that a lot of people send their suspension off for a re-valve or other magical rework when they could have greatly benefited from just getting their suspension, chassis and controls dialed in to as close to optimum for their riding style as possible beforehand, and shockingly can frequently be achieved with stock OEM suspension, which is especially true when working with a modern motocross style dirt bike.
With the availability of technology that comes stock on current motorcycles, setting a modern motocross style dirt bike up for a riders height, weight, riding style such as Motocross, Off-Road Disciplines (GNCC Racing, Enduro's, Hare Scrambles etc), as well as Freestyle Motocross and taking into consideration the individual riders ability, an optimum setup can frequently be reached with just optimizing the motorcycle's available settings, and all without sending your suspension off for any fancy, expensive re-valve loaded with internal anodized parts you might not have needed. Even if you are the type that rides a vintage style motorcycle, following the steps outlined in this article can prove to enhance the performance characteristics of an older style dirt bike with remarkable results.
Lastly, setting and tuning of your suspension and motorcycle ergonomics is not a "set & forget" one time job either, as the motorcycle setup will change from one track to the next, as well as needing your input from a screwdriver or T-handle to adjust for terrain and conditions from one outing to the next.
Bottom line here is that the best thing you could do for your bike and yourself if you're interested in getting your dirt bike to handle better than it is, is to follow the steps outlined below before you start unbolting suspension pieces and boxing them up for a trip to a suspension shop for a possibly unnecessary modification.
Topics Regarding Motorcycle Baseline Settings
to Enhance the Handling Performance of a Dirt Bike
- Proper Dirt Bike Maintenance has to come First
- Getting the Machinery Tailored to Fit the Rider
- Getting the Fork's Dialed in...
- Tire Pressures
- Readers Tips on Setups "That Work"
- Up front... A good starting point for a baseline setting on the sag for the front suspension when compressed is around 35-50mm, which should be obtainable through internal shimming by using from about 5mm to no more than 15mm worth of washers stacked under the fork springs, or can also be done by adjusting the spring preload externally as can be done on the Showa SFF (Separate Function Forks) although if an acceptable sag baseline setting is not easily achievable without offsetting the static sag a heavier or lighter spring(s) will be needed.
- And on the Rear... A good starting point for a baseline setting on the sag for the rear suspension when compressed is around 90-105mm, which is adjustable by adding or removing preload to or from the rear shock by adjusting the position of the shock collars and / or by installing a hydraulic preload adjuster as discussed below although if an acceptable sag baseline setting is not easily achievable without offsetting the static sag a heavier or lighter spring will be needed.
- Begin by placing the bike on a stand so both wheels are elevated and off the ground with the front and rear suspension fully extended.
- Using a metric tape measure, or one of the trick aftermarket sag measuring tools, measure the extended distances of both the front and rear suspension and note these measurements in the appropriate fields in either the Advanced Setup Log or the Basic Setup Log, both of which are excellent, free downloadable log sheets that have appropriate fields for this.
- With the fully extended measurements noted, have the rider climb aboard the bike and bounce the suspension as mentioned above, then take a measurement of both the front and rear suspension at the exact same locations that you took the measurement from with the bike on the stand.
- Once a measurement is obtained with the rider on board and you have a pretty good idea of how much of a change is needed, have the rider dismount the motorcycle and then place the bike back on the stand so the wheels are elevated
- Once the weight of the motorcycle is off of the springs, adjust the front sag by either adding preload to the fork spring via the external adjuster found on the Showa Separate Function Forks (SFF) or by placing shims under the fork springs on a conventional style fork, as well as on a twin chamber or cartridge style fork but be sure to recheck the race sag and unladen / static sag as discussed below before sending the rider out, and refer to a factory service manual for dis-assembly of the forks if necessary.
- When adjusting the rear sag, do so with the rear wheel elevated by adjusting the spring preload on the shock by turning the preload rings or even by dialing in the the sag by using a hydraulic preload adjuster.
- Once you have reached the sag measurement(s) that you feel are ideal and a good baseline setting or starting point, place the dirt bike back on the same level ground that you used for measuring the compressed sag when the rider was aboard and compress the suspension again vigorously by hand, then grab the rear fender and lift up on the rear of the motorcycle effectively "topping out" the suspension, then quickly let go while holding the handlebars with one hand to balance the bike and allow the motorcycle to sag under it's own weight, then take a measurement using the point of reference as before to reveal the rear shock's unladen sag. The ideal unladen sag for the rear shock while or after measuring and adjusting the rear sag using the same conditions such as fuel level and any mud accumulation (if applicable) should be 15 to 25mm. If you're unable to achieve an unladen sag of 15-25mm after setting the sag be sure to see the next section on determining whether you need a heavier or lighter spring for the riders weight.
Proper Dirt Bike Maintenance has to come First
Before you even bother with baseline settings, or any other setups, It is crucial that you ensure the motorcycle is in a good solid and sound condition, which there are several tips surrounding this that can be found on the page covering dirt bike maintenance and a topic that really needs attention before any adjustments such as setting the race sag on most bikes is ensuring the swingarm and linkage bearings are lubricated and not binding or worn out.
Once you have taken care of the basic maintenance surrounding the motorcycle and it's suspension, you may also want to consider having the oil changed in both your front forks and rear shock(s) before continuing with bringing the motorcycle to a baseline setting to work from, as this is an excellent maintenance task that should be performed periodically.
As mentioned above, there are lots of dirt bike suspension outfits running around that will gladly re-valve your suspension for you but if you just get your baseline settings established first, and work off of those, you may be surprised at how well a dirt bike can perform in stock trim. It's really not rocket science and this article as well as other tips that can be found elsewhere on this site can really get the bike handling the way you've always wanted and intended for it to.
Getting the Machinery Tailored to Fit the Rider
Before getting into making any suspension adjustments such as sag, compression damping, rebound damping or fork tube height it's critical that you first get all the control levers, handlebars and other motorcycle controls set and adjusted properly for the riders size, stature and riding style.
Getting the basic baseline settings dialed in after you've got the controls adjusted to where the bike fits it's rider is free performance that most anyone can do themselves, and can have a tremendous effect on the motorcycle's handling and establishing a baseline setting usually only requires a factory service manual specific to the motorcycle being tuned, along with some basic tools such as a flat blade screwdriver, a few T-Handles, a torque wrench, a hammer and punch, a sag scale (or metric tape measure) and a quality tire pressure gauge and the following are some excellent tips on this.
Just remember that the acceptable baseline settings that are given throughout this article / document are only intended to give you a rough starting point, and are not the most idealistic baseline settings for any particular motocross dirt bike. Also, it is very important to remember that when making changes of any magnitude, to always make the same changes to both fork legs or rear shocks together.
And Remember:
The reason you need a factory service manual is because the ideal baseline settings for an individual motorcycle are only able to be found in a factory service manual specific to the motorcycle being tuned and they are established throughout extensive testing, research and development (R&D) by the manufacturer of the motorcycle and / or suspension component, and it truly is important that a factory service manual specific to each individual motorcycle is referenced.
Additionally, If a motorcycle's suspension components have been modified, the baseline settings given in a factory service manual specific to the motorcycle will no longer apply, in this event, you'll need to contact the suspension builder that modified the suspension for a recommended baseline setting to base your adjustments / settings off of and if you bought a used dirt bike that the suspension was previously modified on, you may want to contact the previous owner (if possible) and ask them for what weight and skill level of rider the suspension was set up for, including any information on who performed the modification(s). If contacting a previous owner of a dirt bike does not seem possible you may consider sending the suspension components to a reputable suspension builder and ask to have the suspension valving returned to an OEM spec or have it valved for your particular riding style, weight and skill level.
Lastly... The proper term for the action of which your suspension performs is “Damping” NOT “Dampening” as is so commonly heard and misunderstood.
Unless the suspension has been modified prior such as oil level and / or valving adjustments having been performed, or the fork seals have lost fluid (at which point the fork seals would need replaced and the oil changed then set to the factory level) the fork oil levels and internal valving specific to compression damping should not need any attention while only obtaining a baseline setting to work from.
Getting the Fork's Dialed in...
Remember, when setting the compression damping on the forks, the adjustment at the top of the fork leg on a twin chamber fork is compression, and on a cartridge fork the compression adjuster is at the bottom. Also, the value listed in the service manual will be clicks from full hard which means that you turn the adjuster clockwise until it seats lightly, then turn the adjuster out the specified number of “clicks” being certain to set the value specified on both forks simultaneously unless working with a Showa SFF (Separate Function Forks)
Fork Height / Fork Tube Overlap
Obtaining the baseline settings of your fork height / fork tube overlap is an excellent place to begin. If you don't know where your forks are currently set at, or if you don't understand why your front end is pushing (e.g. Not turning when the handlebars are turned, and rather just sort of plowing through a turn or washing out with you fighting the bike for control) or if your dirt bike is head shaking (e.g. Giving violent and frightening tank slappers) or knifing into a turn (e.g. Cutting in too sharply / over reacting to input) when you attempt to make a turn, setting your fork height / fork tube overlap is an excellent starting point.
When making changes to your fork tube height / overlap, it is wise to not try to “Eye-ball” it and instead, use a precision machinist steel rule at a minimum to measure the fork tube height / overlap, although use of the depth measurement function on a vernier caliper is the most ideal method, just be sure that if you do make changes to the fork leg height, that you ensure that the forks are not binding and that you re-torque the triple clamp pinch bolts to the manufacturers recommended torque as can be found in a factory service manual specific to the motorcycle you are working on.
On most modern motorcycles with inverted forks aka “upside down” or “USD” forks there will generally be a line etched into the fork slider which is the point that the manufacturer recommends for a starting point for fork height and before continuing, it is recommended that the forks be brought back to this point while ensuring that the forks are not in a bind when the pinch bolts are re-tightened.
Once you have a baseline setting established for your fork height / overlap, here are a few tuning tips regarding fork height that may help.
If you want greater high speed stability (less head shake)
If your motorcycle's turning seems to be responding too sharply (e.g. The front end knifes in) or you're experiencing head shake elsewhere such as between jumps and other high speed sections, you can lower the fork tubes in the triple clamps to correct some of this, but only make small changes when lowering your forks in the triple clamps and keep in mind that the lower the fork tubes are in the clamps, the less responsive the turning abilities of the motorcycle will seem.
If you need greater or quicker turning abilities
(and you're not experiencing head shake)
If you are having problems with the motorcycle turning (e.g. The front end pushes “The front end washes out”) you can raise the forks in the triple clamps to establish a better turning motorcycle, but only make small changes when raising your forks in the clamps and be cautious of head shake when doing so, since raising the forks will steepen the steering angle of the motorcycle which can initiate a head shake condition, especially at high speeds when things get hairy with handlebars that are hard to hold on to.
If you have a twin chamber fork, the compression damping will be the center screw on the top of each fork leg except for the Showa Separate Function Forks (SFF) which only has the compression damping on the left side, as the externally adjustable preload adjuster is on the right side. When looking at the top of the fork on a twin chamber style fork, you should see the marking of "comp" near the screw with a rebound adjustment at the bottom of each fork leg, again with the exception of the Showa Separate Function Forks (SFF) only having rebound damping on 1 side.
Conversely, on a cartridge style fork, you will find the rebound adjuster at the top of each fork leg and the compression damping adjuster at the bottom of each fork leg, both of which are opposite of how they are positioned on a twinchamber fork.
Low Speed Fork Compression Damping
As the term "Compression" implies, the fork's compression damping adjustment is for tuning how quickly the forks compress when the front wheel is traveling over rough terrain or when absorbing hard hits, as well as when landing from jumps.
What about
High Speed Damping?
Adjustment of the fork's compression or rebound damping circuits can be altered either internally or externally, but since this article is primarily about obtaining baseline settings of the motorcycle, only external low speed compression and rebound damping adjustment is going to be covered here since internal compression and rebound damping adjustments are an aspect of fine tuning, as modification of these circuits is what “Re-Valving” is and is generally not regarded as baseline settings.
While referring to a factory service manual specific to the motorcycle you're working with that the forks have not been internally modified on, it is recommended that you set the low speed compression damping circuit to the baseline setting as will be described in the book, although if a factory service manual is not readily available, setting your externally adjustable low speed compression damping to 10 clicks out from lightly bottomed, which is a “full hard” setting is a pretty close baseline setting that should work well as a starting point for a wide range of riders.
Fork Rebound Damping
As the term "Rebound" implies, the fork's rebound adjustment is for tuning how quickly or slowly the fork extends after being compressed such as when landing from a jump, absorbing a hard hit such as a G-Out as well as when traveling over rough or irregular terrain as well as even having an influence on the front tire's contact with the terrain.
Just remember... Rebound damping adjustment on twin chamber forks is at the bottom of each fork leg (with the exception of the Showa Separate Function Forks (SFF) which only have damping adjustment on 1 side) and rebound damping adjustment on cartridge forks is at the top of each fork leg, otherwise adjustment of the rebound damping is the same principle as compression damping adjustment as you will turn the adjuster in fully until lightly bottomed, then back the adjuster out the specified number of clicks as can be found in a factory service manual specific to the motorcycle you are working on, although if a factory service manual is not currently available, turning the rebound adjuster out 10 clicks from lightly bottomed which is a “full hard” setting and can be a comfortable baseline setting to work from.
Measuring and Setting the Suspension Sag / AKA "Race Sag"
Having the race sag set properly is one of the best things anyone can do for the handling characteristics of a dirt bike but commonly goes untouched...
Some riders wonder why all the talk about sag is and seem to think this is a set & forget type of thing but constant adjustment of your sag from a baseline setting is critical to the optimum performance of a motorcycle.
Having your sag set properly is important for numerous reasons and can affect the way that a motorcycle handles such as steering and the way the rear end reacts to chop, braking bumps, leaving the face of a jump and high speed stability so staying on top of the race sag is highly recommended.
When Making a Rear Sag
Adjustment...
Before setting either the front or rear sag you need to ensure that your rear suspension is in good shape and not binding or suffering from any slop, and there is an excellent article on everything you need to know about servicing your rear suspension right here.
When setting either the front or rear race sag, it is best to do so after a short session of riding the dirt bike in the elements that it will be used in such as after any available practice, as this will allow the suspension to get warmed up, thereby ensuring all the parts are moving freely and reducing any chances of “Stiction” affecting your measurement.
Additionally, when measuring or adjusting the sag, be sure that the bike has the same amount of fuel as it would normally have for a race or practice session, ensure that the rider is in full gear ready to race / ride and if you are preparing the bike for a muddy event, and if there is mud accumulated from the warm up ride or practice session, leave the mud intact, as this will be additional sprung weight which can affect the measurement when measuring or setting the sag.
Taking the Measurements and Setting the Race Sag
Since sag measurements are not usually discussed in a factory service manual, the steps below should provide you with all the information you will need to obtain an accurate sag measurement, just remember that when taking a measurement of the suspension sag, it is imperative that the same point is consistently referenced both when measured on the stand and in a compressed state.
When measuring the rear suspension...
You may find it useful to make a small mark on the rear fender with a sharpie marker so the same point can be easily located and referenced each time the sag is measured or adjusted, as this will help with obtaining consistent measurements in the future.
When measuring the front suspension...
You'll likely find it will be best to measure from the axle to the bottom of the triple clamp, as these points are easiest to get a reliable, accurate and consistent measurement from and a tape measure works the best for this.
Note:Considering the importance of achieving an ideal reading, and in an effort to avoid any stiction (“Stiction”= Sticking caused by the natural friction created during the movement of the shock shaft / piston in the shock body, or the fork tube moving within the fork slider) of the suspension which could alter a reading and cause your race sag's baseline setting to be inaccurate, it's important to roll the bike and bounce the suspension before taking a measurement as mentioned next.
Before taking a compressed measurement with the rider on board, it is best to roll the bike fore & aft while the rider aggressively bounces the suspension which can also be accomplished best by the rider riding the bike around briefly while bouncing the suspension while in motion, and then allow the bike to come to a stop without ANY application of either the front or rear brakes or any other influence in stopping, then with the rider in the normal riding or racing position that is the most comfortable and natural while simulating an attack position take the compressed measurement.
The ideal targets you are looking for when setting the sag are as follows:
Determining whether a Heavier or Lighter Spring is Needed
After setting the rear sag as detailed above, if you're left with an unladen sag measurement of less than 15mm, the rear spring is too soft for your or the riders weight and conversely, if the unladen sag is more than 25mm, this would indicate that the spring is too stiff for your or the riders weight.
Why you'll need a Stiffer Spring
If there is not much unladen sag left (less than 15mm) after setting the rider sag, this means that you have the preload cranked down so tight on the spring that it is holding the bike up too high in the rear, and the motorcycle needs a stiffer spring in order to get the rider sag and unladen sag balanced.
Why you'll need a Softer Spring
If there is more than 25mm of unladen sag after setting the rider sag, this means that the spring likely has almost no preload (or not enough) and the motorcycle needs a stiffer spring to achieve a balanced rider sag and unladen sag measurement.
Getting the Rear Shock(s) Dialed in...
Getting the baseline settings for the rear shock absorber(s) dialed in can be done externally and doing so can have remarkable results as to how the motorcycle handles if the adjustments are out of whack.
On rear shock absorbers with adjustable compression damping there may be two externally adjustable compression damping circuits on your particular model, and the low speed compression damping circuit will be the most inner of two adjusters, as the high speed compression adjuster is usually the outer part of the low speed compression adjuster and has wrench flats machined into it for adjustment via an open end wrench, unless working with an Ohlins Shock in which case on some models there may be separate knobs placed side by side for external adjustment of low and high speed compression circuits.
Rear Shock Low Speed Compression Damping
The rear shock's low speed compression damping circuit is most active when landing from jumps, charging through widely spaced whoops and bottoming out.
To determine the manufacturers recommended baseline setting for low speed compression damping, it will be necessary to refer to a factory service manual specific to the dirt bike or shock absorber that you're working with to obtain the manufacturer's recommended baseline setting. If a factory service manual is not readily available, you can likely set the low speed compression damping at 10 clicks out from lightly bottomed which is a “full hard” setting as this is a good baseline setting to work from and then fine tune this circuit from there.
Rear Shock High Speed Compression Damping
High speed compression damping is a damping circuit that is not available on all rear shocks, but on those that are equipped with high speed compression damping, the rear shock's high speed compression damping circuit is most active in high speed wheel movement sections such as square edged chop, braking bumps, roots or rocks, and can be tuned by adjustment of the knob with wrench flats that is external of the low speed compression damping adjustment, or with the separate external high speed compression adjuster found on some Ohlin's shocks.
To determine the factory recommended baseline setting for the rear shock's high speed compression damping circuit it is necessary to refer to a factory service manual specific to the motorcycle you are tuning, although if a factory service manual is not readily available, a good baseline setting for the high speed compression damping circuit is 1-1/4 – 1-1/2 turns out from lightly bottomed which is a “full hard” setting.
(Note: The high speed compression damping adjuster on OEM style shock's with high speed compression adjustability is generally adjusted in quarter turns and does not have detents, so there will likely not be any “clicks” noticed during adjustment of the high speed compression damping circuit.)
Rear Shock Rebound Damping
The rebound damping is what controls the rate at which the rear shock extends after being compressed and the rear shock absorber(s) rebound damping can be adjusted and brought to a baseline setting or fine tuned thereafter on shock(s) equipped with adjustable rebound damping.
To adjust the rebound damping of a rear shock, there will be an adjustment on the shock clevis near the bottom of the shock. To determine the factory recommended baseline setting for the rear shock's rebound damping it will be necessary to refer to a factory service manual specific to the motorcycle you are working on tuning, although if a factory service manual is not readily available, a good baseline setting for the rebound damping is 10 clicks out from lightly bottomed which is a “full hard” setting.
Tire Pressures
Obtaining a baseline setting for tire pressures according to different types of terrain is another factor that needs attention when going from one track or riding area to the next, and this is also true for changes in terrain or weather and the table listed below can give you a pretty good idea of a baseline setting to start with regarding tire pressures but be sure to use a quality low pressure, tire pressure gauge when making changes to tire pressures as the quality tire pressure gauges that are available have a bleeder function for making incremental changes to the tire pressure.
| Hard Terrain Clay, Hard Pack Dirt, Rock |
Intermediate Terrain Loam or Loose Soil |
Soft Terrain Sand or Mud |
| 14 psi (Cold) | 12 psi (Cold) | 10 psi (Cold) |
| 12 psi (Cold) | 10 psi (Cold) | 8 psi (Cold) |
Readers Tips on Setups “That Work”
Do you have a setup that worked well at a particular motocross track, off-road (OHV) area or freeride area?
Do you know the inside scoop on how to make a particular bike perform better? Share it with us right here.
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