Off-road Suspension Guide
We feel that understanding the basic suspension tuning can give you an advantage over your competition, or simply make your riding experience much better. For this reason we have put together a summary of basic suspension tuning and common problems experienced while setting up your bike for different terrain and riding conditions.
Getting Started with Motocross Suspension Tuning
Different conditions require slightly altered settings. There can be major differences in which setting’s, spring rates and etc can improve the riders suspension setup. Lets start off with installation of the forks.
The installation of forks is most often done incorrectly. You need to make sure that your fork tubes aren’t in a bind. First slide the fork tubes into the clamps. Make sure you have the pinch bolts loose, the tubes should slide in easily ( if they do not make sure that you do not have a damaged or bent clamp ) after sliding the fork tubes into the clamp set the fork height that you want. Hand tighten pinch bolts. Then using a torque wrench tighten pinch bolts to the proper settings. (see manual for torque specs) Now install the wheel and make sure your axle is clean and has a coating of lube. Slide the axle into position. Now hand tighten the axle nut and bolts on just that side.This is where you need to make sure the forks aren’t in a bind. Using a screwdriver you need to spread the pinch bolts on the opposite side. This allows the fork leg to move freely on the axle to make sure we have a proper alignment. Spin the wheel the torque hit the break to shock the tubes into place on the axle. Then proceed to tighten pinch bolts. (see manual for proper specs)
When installing the shock it is critical that the linkage is inspected and is in good working order. (see manual for torque specs)
After installing the forks and shock it is now time to set the Sag.
Static Sag for the Shock
Use a metric tape measure for the following steps. These next two steps are the MOST IMPORTANT in getting the most out of your suspension. For this measurement you will start with the bike on a stand so both wheels are suspended. The best way to do this is after you have ridden the bike and have the shock warm. Find a spot from the center of the rear axle up to the rear fender and measure these two points. Write the measurement down and set the bike on the ground. (rider not on the bike) Using the same two points take another measurement and the difference should be (35-40mm NO LINKAGE)(30-35mm WITH LINKAGE). If it is not you will need to adjust the spring tension. You do this by loosening the shock locking collar then increase the spring preload by tightening (clockwise) the shock collar or decrease the spring pre-load by loosening (counter clockwise) the shock collar to get the proper measurement.
Race sag is a measurement taken to determine if you have the proper spring rate for your weight and must be done after setting static sag. Now with your riding gear,camel pack,tools etc. on. Take the bike off the stand and get on the bike in a standing position with balls of feet on pegs with legs straight and grip one handle bar grip with one hand while lightly using the other hands finger tips on a wall for balance. The rider will get a better measurement this way. (The reason for STANDING is simple, it is consistent)
(Measurement 1) Rider on bike
Lift up on the rear slightly (about 20mm) and SLOWLY release it downward. Write down measurement.
(Measurement 2) Rider on bike
Compress the rear suspension slightly (about 20mm) and then SLOWLY release back up. Write down measurement.
(Measurement 3) Bike on stand fully extended
The difference between lifting up and pushing down is caused by friction. The greater the Stiction the more friction there is. If it is more than 4 or 5mm the linkage needs attention.
The actual sag is calculated by averaging Measurement1 and Measurement2 and subtracting it from fully extended.
Static sag = M3 – (M1 – M2)/2)
Note: FREE SAG is the amount the bike compresses with the weight of the bike only – no rider. Use the same method as outlined for Sag.
The measurement on a bike without linkage should be 105-115mm and if your bike has linkage it should be 100-110mm of total sag. You get this measurement by subtracting rider on the bike measurement from the bike on the stand measurement. If the number is less than the listed measurements the spring is too stiff. If the measurement is greater the spring is too soft.
Compression & Rebound Tuning
Setting the fork rebound
The rebound damping is responsible for the stability and the cornering characteristics of the motorcycle. Find a short sweeper. When the forks compress for the turn, the speed at which the forks return is the energy that pushes your front wheel into the ground. If the forks rebound too quickly, the energy will be used up and the bike will drift wide, or wash. If the rebound is too slow, the bike will tuck under and turn too soon to the inside. With the bike turning well, the wheel should return to the ground quickly and not deflect off successive impacts. If it does, reduce the rebound. (Turn out)
Setting the shock rebound
Find a relatively fast trail with braking bumps, rocks or roots leading into the entrance of a corner. Reduce the rebound damping by turning the rebound adjuster (bottom adjuster on shock) counter clockwise until the rear end begins to hop or feel loose. Then turn the adjuster back in clockwise a few clicks to increase the rebound damping until the sensation goes away. Find a log or ledge that tends to bounce the motorcycle after hitting it. If the rear end bounces up uncontrollably, make sure that the static sag is correct. If the static sag is correct, turn the compression (top) adjuster counter clock wise 3 clicks and turn the rebound adjuster in (clockwise) 3 clicks. Find some large whoops. The motorcycle should track straight through the whoops with the rear wheel extending to the ground before the next impact. If it does not perform as described, as above, it is packing and the rebound dampening should be reduced! (Turn clicker out) (Please go to the section for sand set-up, as these rules don’t apply for sand.) Find a corner with acceleration bumps, rocks, or roots on the exit. The rear of the motorcycle should follow the ground. If the rear end “breaks up”, reduce the rebound. (Turn clicker out) (If this fails soften the compression two clicks.) (Turn clicker out)
With the bike turning well, the wheel should return to the ground quickly and not deflect off successive impacts. If it does, reduce the rebound. (Turn out)
Setting the fork compression
The forks should react to all trail variations. If the forks seem harsh on small bumps, holes, rocks, or roots soften the compression. (Turn clicker out) If they are relatively smooth, stiffen (Turn clicker in.) until they do feel harsh and then turn back a click or two. Now find the rough part of the trail again. The forks should bottom over the worst g-out or jump.
Setting the shock compression
Find some rough sections, a large jump or a couple of “G-Outs”. The shock should bottom on the roughest section but it should not be a slamming sensation. Add compression to reduce bottoming. (Turn clicker in.) But avoid going too far as the suspension’s ability to react to small variations of surface and rocks will be sacrificed in the trade. Remember the adjusters have a primary effect on the low speed, so even a large change in setting may only affect bottoming resistance slightly.
Remember bottoming your suspension is not necessarily a bad thing. You should strive to bottom off the biggest bottoming load obstacle on the trail. If you don’t you are not getting maximum plushness from your suspension. Run your suspension as soft as you can get away with but remember that if the trail has sand sections or lots of g-outs this will work against you.
Guidelines for different conditions
For hard-pack to intermediate: Set the compression softer, (Turn clicker out) front and rear to help get maximum wheel contact and plushness.
(Non-square edged bumps) More low speed compression and rebound are necessary. Start by adding 2 clicks (Turn clicker in.) of rebound and as the track gets rough, add compression 4 clicks. (Turn clicker in. Harshness is a result of packing in forks. Remember to add compression (Turn clicker in) to help keep the front end from packing The rear suspension will exhibit packing by swapping. To eliminate swapping begin adding compression (Turn clicker in) until the bike tracks straight and then add rebound (Turn clicker in) to keep the rear following the terrain of each whoop.
Rocks and Roots
Rocks and roots will make your suspension work at its worst. Try reducing compression and rebound so the suspension can react and not deflect off every impact.
Adjust the forks lower in the triple clamps. If that does not improve the suspension then reduce the rebound on the front fork. (Turn out)
Excessive rear end kick
Check for packing, which is identified by kick to the side in hard to loam conditions. If you observe packing, soften rebound. (Turn clicker out.) This can not be avoided if you brake improperly and lock the rear wheel up and/or pull in the clutch, on the entrance to corners.
Note: Keep a record of the conditions and the different settings if you ride in different areas.That way you can start at a point that worked well the previous times.
Remember that if you make the suspension too soft you will use lots of energy just maintaining direction, and control. Be careful when you set it, there is a difference between soft and plush. Soft is often hard to control and harsh, while plush is smooth and controlled. The goal is to maximize control and comfort. Think about the entire section of trail or the average conditions of the trail. Factor in your skills as a rider and then select the setting that will provide the best overall ride characteristics. Consider that in off road riding you will encounter an incredibly wide range of conditions and you’ll need to shoot for the middle ground or your suspension will be very good in some sections and average in others.
The dampening of suspension changes as the components are used. This is caused by wear and oil viscosity breakdown. It is important that your suspension has regular maintenance. Improper assembly or inadequate fluids will drastically alter the way these components were designed to perform. The shock’s oil should be changed every 3 months under heavy usage. Seals will generally last a season, so once a year we recommend replacing them. For the forks, we recommend that you bleed off the air pressure before each ride. A complete service is suggested every 3 months depending on how much sand or mud you ride in.
Cleaning fork dust and oil seals
- Clean entire area around the DUST seal and remove fork guard.
- Use a small flat head screwdriver to assist in sliding away the DUST seal, exposing the OIL seal.
- Clean entire area around OIL seal. Use a spray bottle with soapy water (Dawn dish detergent works well for this) and a soft brush to loosen debris. Use fresh water to wash away debris. Use low air pressure and a towel to remove water being careful not to damage anything. Carefully insert BACK END of SEAL MATE TOOL or Seal Doctor between the seal and fork tube. This should be inserted approximately 1/2″ deep.
- Gently rotate SEALMATE around fork tube making sure that the HOOKED END is the leading edge.
- After a complete rotation, CONTINUE rotating SEAL MATE as it is being removed.
- Wipe down entire area (fork tube and seal).
- Grab the front brake and COMPRESS (pump) the forks several times.
- Wipe off entire area (fork tube and seal).
- Pump again
- Inspect fork tube for excess oil. If excess oil is present repeat steps 8-11.
- Use a spray bottle with soapy water and a soft brush. Use fresh water to wash away debris. Use low air pressure and a towel to remove water being careful not to damage anything. Clean and apply a small amount of suspension lube just below outer tube. Rotate dust seal over lube to evenly coat tube and dust seal. The lube will prevent stiction and help prevent premature seal wear. Return DUST seal to original position.
- Reinstall guard