Suspension Explained

Your motorcycle suspension is designed to keep in contact with the ground, make for a comfortable ride, allow you to turn a corner as you like and provide forward drive. Many experts will tell you that the single biggest benefit to making a rider go faster is suspension. Get this right, and you will have a ride that is very rewarding. With so many different ranges of adjustment available, many people are not keen to set up their bikes. Hopefully after reading this, it may encourage riders to try and learn how to make adjustments and improve the capability that their bikes can provide. Then once understood, settings can be confidently made for the different tracks and terrain that the rider is likely to use.

Before you start

Tyre Pressures
On many MX tracks, set both front and rear tyre pressures to 12psi. MX tracks are generally very similar with a mix of sand, mud, rock and dry clay base. Many tyres also benefit from this pressure so it is easier to have one thing that never changes. If you change your tyre pressures to suit a particular track, you will need to adjust your suspension settings to suit as well. It is far easier to make changes to your suspension only rather than tyre pressure and suspension.

Compression and Rebound
Compression is when the spring is compressed under load by either jumping, hitting bumps, braking, accelerating and riding. Rebound is the spring returning back to it's normal state. Inside the forks and shock is oil which helps control (damping) how quickly the spring compresses or rebounds.

Rebound Damping
After the spring has compressed during travel, rebound is how quickly the spring returns back to it's normal state before being compressed. If the rebound is set too fast, the bike may kick up over bumps or when accelerating out of corners. If the rebound is too slow, the suspension may 'pack' meaning the suspension will not return back to it's normal state before hitting the next bump.

High Speed Compression Damping
Used when hitting a square edged bumps, whoops or corrugations will cause the the spring to be compressed very fast. Generally small violent hits to the suspension.

Low Speed Compression Damping
This is mainly with jumps or larger rounded bumps. Reasonably easy on the suspension and not such an impact to the suspension. Low speed compression can also help reduce brake dive and reduce the amount of rear end squat under hard acceleration.

SAG settings
SAG is the starting point of all suspension settings to be performed. Static Sag is the weight of the bike fully fuelled and balanced by itself. Rider or Race sag is when the fully clothed rider is on the bike in their normal riding position. To set these up, refer to your owners manual. These settings can best done at home when you have plenty of time and friends to help you. After completing your SAG settings, from your manual, set all suspension settings to their recommended settings (race or comfort).

Now the fun begins!!

As a general rule, front suspension can be done by the rider alone as the forks give instant feedback to the rider. With the rear, get another person to watch you ride and they will be able to see what the rear is doing as it can be difficult for the rider to feel what is happening. It is very easy to see if the rear end is kicking up over jumps or if the rear wheel is pogo'ing (oscillilating) when accelerating out of corners or off jumps.
Now ride around a track that you know well so you can feel what the bike is actually doing when travelling around the track. Starting with corners, does the bike drift wide (understeer) or dip in too quickly (oversteer) at the front. Most of the adjustments to your steering will be done by adjusting the forks. If the forks settings are at their limits or if nothing seems to work for you, try the shock adjustments. When making adjustments at this point, use 2 clicks at a a time.

Runs wide in corners
Front tyre climbs out of ruts
Understeer Increase rebound on the forks
Decrease fork compression
Decrease rebound on the shock
Decrease shock compression
Tips into corners Oversteer Decrease rebound on the forks
Increase fork compression
Increase rebound on the shock
Increase shock compression
Rear wheel pogo'ing/oscillating
Rear wheel fish-tailing under acceleration
Decrease rebound on the shock

When landing from a jump, does the bike bottom out on it's travel? If yes, adjust for stiffer(more) compression damping. If the bike isn't using the full travel (on big impacts), adjust for less compression damping. If you are unsure of how much travel is used, tie a cable tie around the fork legs and shock absorber and measure the amount used (refer to your manual for travel length). Increase or decrease the compression damping until the suspension uses it's full travel stroke but not bottom hard.
Hint Generally, adjust rebound first as it will give a very quick indication on the next ride through the corner. If there is too much compression, the ride will be harsh and it will feel like you have been beaten up after going for a ride. Soften the compression so the ride is more compliant to your body!

Bumps, Whoops & Holes
Hopefully by following the setups for jumps and corners, the suspsension should now be fairly good and with any luck, only very minor adjustments (one click at a time) will need to be made for bumpy terrain.

Front end deflecting on bumps Fork compression too hard
Fork rebounding too fast
Front wheel skipping over bumps Fork compression too soft
Fork rebounding too slowly
Front wheel chatters over small bumps during braking or downhill Fork compression too hard
Rear end kicks up on braking bumps Shock compression too stiff
Shock rebounding too quickly
Rear end oscillates under acceleration Shock compression too soft
Shock rebounding too slowly
Rear end kicks up on jump takeoff Shock compression too stiff
Shock rebounding too quickly

When riding over whoops - note how the rear end feels. If it feels good on the first few bumps and becomes harsh gradually, this could be because the shock is packing down so increase rear rebound two clicks. If you are going towards full out on adjustment and the suspension is still feeling harsh, your problem may not be packing. It could be that your compression is too soft, and you are actually bottoming out. Reset your rebound adjuster back to the standard and start adding more compression, two clicks at a time. Run your test section when adding compression; you should start to feel the bike stay on top of the bumps.

Due to the nature of race tracks, it is impossible to have a suspension setting that works every where around the track. As a racer. you need to decide what suits you most at the track.

Adjusting your suspension can be time consuming but once done, it gives you more confidence making you faster and ultimately, a safer rider.