When manufacturers build a bike they have to take into consideration many variables. Variables such as rider weight, rider speed, track speed, terrain, riding style and conditions must all be taken seriously to provide a bike to the public that will be a good balance for everyone.
Spring weights and dampening circuits are somewhat averaged out to suit an average rider on an average track. These standard bikes are set up to suit a person that doesn’t really exist (ie: a compromise).
If you are serious about your riding or racing, or just making your motorcycle suit you to a tee, you need a bike custom set-up for you to allow you to get the most from your machine.
A good suspension tuner will set your bike by adjusting spring weights, ride sag and dampening circuits/valving to suit where and how you ride. “Ride sag, dampening circuits, valving?”, you ask? These are all important and give the tuner the capability of changing the internal settings of your suspension unit.
The internals of your suspension all control oil flow. It can be adjusted by changing valve shimming, pistons, oil, oil viscosity and even oil quantity. How stiff your springs are and how much pre-load they have all should be set by an industry expert that solely specialises in suspension within your field of racing.
You have probably heard people tell you to set your ride sag on your rear shock before you ride. This is very important as it effects how the bike is balanced whilst on the track with the rider. Your forks come pre-set and should only be changed by an expert tuner in the field. They will be able to tell you if the spring is too hard/soft, how much sag to run with your weight and setup and keep your bike balanced.
The more information you can supply your tuner, the better the end result will be. Included in this tech section is information on things you can tune yourself (either before or after a visit to us!) and some guidelines for adjusting your suspension depending on various types of racing conditions.
Note that even though these sections cover MX disciplines, the same principles can be applied to any off-road riding.
Setting your ride sag on your rear shock will have an effect on the way your bike sits out on the track. Too much sag and your bike will sit low in the rear, wallow around and will turn about as sharp as the titanic. Too little and your bike will be prone to head shake, sit high in the rear, kick under brakes and will over steer and tuck through corners. In both scenarios front wheel washouts are a common crash in result from incorrect ride sag.
The following are only general recommendations, different riding styles, tracks and manufacturer brands may vary these setups.
70 – 75mm
85 – 90mm
125 to 650cc:
100 – 120mm
• Measurement 1
Place the bike on a stand with your wheels un-weighted. Take a measurement from the rear axle to a fixed point vertically above (eg. muffler bolt/rivet). Making a small mark with a pen on the guard for a reference point is a good idea.
• Measurement 2
Take the bike off the stand, place the rider with gear on the bike with a normal riding position with their feet barely touching the ground or on the pegs with someone helping to aid balance. Take another measurement from the same two points as before.
Too much rider sag indicates you must increase pre-load to the spring by firstly loosening the spring adjuster found at the top of the spring. Then adjust by turning the lower adjuster ring clockwise. Too little rider sag indicates you must decrease pre-load by turning the spring pre-load adjuster counter clockwise.
Next you should check your bike’s free sag.
• Measurement 3
Take the bike off the stand and bounce on the bike to allow the suspension to settle. With the rider off the bike take a measurement between the same two points again.
• Free sag
Subtract measurement 3 from measurement 1. Your bike should sag approximately 25 – 35mm by itself off the stand after your have set rider sag.
Hint: Less than 25mm indicates a stiffer spring is needed and more than 35mm indicates a softer spring is needed.
After setting the bike to your weight and speed, further adjustments can be made whilst at the track through the use of the adjusters that come standard on your motocross bike. Spending time to “dial” your bike in will result in a safer easier ride that grips harder to the track, allowing you to (most importantly) set faster times and win races.
Compression adjusters: Hard to Soft
These adjusters generally determine how hard or soft your suspension will be, but will be mainly be a fine-tuning adjuster. The compression adjuster on your forks can be found at the top of twin chamber forks and on the bottom of forks fitted with conventional cartridges. Consult your manual if in doubt.
When adjusting these settings wind the adjuster all the way in (clockwise) with a flat blade screwdriver then count in clicks out (eg. wind all way in and count back out 14 clicks). Winding the comp adjuster clockwise will effectively slow the dampening circuit resulting in a harder ride and adjusting anti-clockwise will result in a softer ride.
The compression adjuster on your shock generally comes with two settings on late model MX bikes, enabling you to adjust the high-speed circuit and the low-speed circuit. Some bikes still may only have a low speed adjuster screw. The adjuster is found on the shocks reservoir with a high speed outer ring usually adjusted by a 14 – 17mm hex socket and the low speed adjusted by an inner screw. The high speed adjuster is counted in turns (eg. wind clockwise all way in and back out 1 and 1/2 turns). A large T-bar is the best tool for this job. You will mainly need to adjust the high-speed circuit for increased dampening on heavy landings found on big jumps and G outs found through the track. The low-speed circuit is mainly adjusted for bumps in and out of turns and low to mid size hits.
Rebound adjusters: Slow to fast
The rebound adjusters on your machine enable you to control the return of the stored energy created by the spring. Too little or too much dampening will result in bike that kicks and is hard on your arms. These adjusters are quite sensitive and should be used carefully.
They are found on the opposite end of forks to compression and on the lower shock clevis. They are adjusted similar to comp adjusters winding in all the way in clockwise will slow the dampening circuit and winding out will effectively speed it up.
After you have your base settings and spring rates set by your suspension shop you will need to head out to your local tracks to get some settings for the various conditions encountered. All testing that you do should be recorded. Tyre pressures/brands, fuel load and track conditions all should be recorded as they all have an effect on your suspension. Starting with your base settings all-testing are best done with one change at a time with rider feedback and a good eye from a friend deciding on improvements. Having a quick glance through your race calendar will give you a guide on the type of tracks you have to be prepared for enabling you to test on tracks with similar conditions.
Due to the dry weather conditions found here in Australia, we find ourselves racing and pounding out practice laps on hardpack clay tracks. These conditions are often quite slippery both in the wet and dry and generally have lots of small sharp square edge bumps on both entry and exit to turns. They are often quite unforgiving on the rider, making a little mistake having disastrous consequences.
The biggest problems encountered with suspension on these tracks are a harsh feeling through the forks, headshake, front wheel washouts and a loss of drive whilst exiting the turns. A good set-up will require your suspension to be set up quite soft. A common mistake on these tracks is to set your bike up quite hard for the jumps which in many cases are only a small percentage of the track. Too hard on the forks will result in front wheel washouts and a harsh feeling through the handlebars.
You also want to have your rebound set loose (fast) enough to avoid packing (suspension doesn’t return rapid enough for the next bump resulting in a lack of grip and travel) on these hard often high-speed circuits. Having a set-up that is generally soft and relatively loose will enable you to drive hard out of the corners, lessen rider fatigue and reduce the occurrence of arm pump that is all too common with these tracks.
Sandy soft tracks found across the country in areas such as Coastal WA and Rosebud VIC require a completely different set-up. With the forgiving nature of these soft circuits, the rider can have a whole lot of fun and let it all hang out with the throttle usually pinned wide open, even around the turns! The down side to these tracks are they often sap a lot of energy from the rider with the big open spaced sand whoops and large braking bumps that form on the entry to tight corners.
Set-up in these conditions is vital to setting a fast time, as a bad corner or line choice down a rough straightaway can lose you more than a few seconds. You will find your bike tends to wallow through the deep sandy whoops and kicks hard and high in the rear under braking.
The key to a good sand setting is to run your bike stiffer in comp F+R to keep it high in the deep sand, handle the constant never ending deep whoops and the usually large jumps and drop-offs found on these tracks. Tightening the rebound a few clicks from your base setting on the rear shock (turn in clockwise) will stop it ‘unloading’ whilst attacking rough straights and also help to reduce the unnerving kick whilst braking.
It will be impossible to get up on top of the whoops and keep driving if your set-up is too soft and loose.
Tracks that consist of both hardpack and soft surface terrain will nearly always require a compromise. Generally speaking, hardpack track with soft sandy sections are often not quite extreme as a full blown sand track, but still build the high braking bumps. More testing to find a balance is the key to success.
Usually a good balance on these tracks is to stiffen the front – to handle the larger braking bumps – but leave the rear a little softer to still maintain drive out of the hard turns. Too soft on the front will only aid the rear kicking over the braking bumps, too hard will cause front wheel washouts on the hardpack.
Working out a percentage of each section on the track will give you a good indication on which way to lean towards when dialling in your machine. Tighten the rebound a little (clockwise 1-2 clicks) on the rear will help with the harsh braking bumps.
Supercross is a totally different world to motocross. With man-made tracks designed to push a rider and their machine to the edge, it is critical that you ride a bike which is solely setup and modified internally for supercross.
Due to the huge jumps and aggressive stutter bump sections on these tracks, your machine will often have to be set up with stiffer springs and dampening rates (front and rear) to suit these tracks. Again these changes should be carefully made by a reputable tuner.
Supercross is a sport which requires ultimate dedication and as every professional will tell you, they need confidence in their bike to simply circulate. Never ride a MX bike on a SX track.
Your bike will need to be stiff enough to give you lift over the jumps and most importantly, save you from injury from an all too easy over jump. They are usually so stiff that when bouncing on it back at the workshop it will seem almost ridiculous, especially on a bike setup for a professional-level rider that weighs 80 kilograms or more. A balance is needed for supercross, as you need to maintain good drive off the gate and also through stutters/whoop sections that can become often very hardpack and slippery or even blow out.
A good tip for watching riders through stutters is to watch the foot peg/boot area whilst attacking them. Too low and the shock is too soft allowing it to compress into every whoop. Getting it right you will see the rider almost ride across the tops of each bump with much more clearance between the ground and their foot peg. Setting the shock too hard will result in wheel spin and lack of forward drive sending the front end down into the often sharp stutters.
Watching the amount of travel used front and rear whist landing and on the take off will give you a good indication of whether it is too hard or soft. Rebound settings are usually valved and adjusted on the hard side resulting in an almost ‘dead’ like reaction.
• Wash your bike thoroughly after riding, especially at corrosive tracks near the sea such as Frankston, Rosebud and Wonthaggi. The parts on your suspension will operate more freely if washed back to ‘brand new’!
• When washing your bike lift up the rubber bump stop on the shock and pressure wash underneath this. This is the spot that corrosion starts to eat at your new chrome shock shaft. The factory mechanics on race teams don’t miss this one.
• Record all your clicker/adjuster settings on your bike even if you never have to change them. This will help when you call your local suspension shop when you are discussing changes or problems you are having.
• Always release the air from your forks at the start of each race day and in between races especially on rough tracks and on hot days. It is a good idea to form a habit of doing this when you are setting your tyre pressures for the day.
• Remember to service your shock when you service the forks. This little guy always gets forgotten about as it never leaks as bad as your forks will. A worn out shock will become springy and be unstable and will definitely fade as race wears on. A good time to service this for a race bike would be 20hrs.
• Always check your forks are operating smoothly. Dirt can build up in the forks bushes and sliders causing stiction in the action. They will feel ‘notchy’ and unsmooth even before your seals start to leak. This problem is common after a mud race and can be easily cleaned up with a service. (new bushes may be required)
• Grease your swing arm and linkages from new with water proof grease and keep them maintained with fresh grease thru out the year to prevent stiction and seizures in the linkage / shock assembly.
• Incorrect tyre pressures will affect your suspension greatly. Always set them before you ride in the morning and again through out the race day.
• Check fork/wheel alignment after big crashes to en sure proper handling and steering before the next race. A rider usually only notices this when riding to the line for race 2 resulting in panic. This is easily fixed in normal cases by loosening and re-tensioning the fork clamp pinch bolts.