MAKE YOUR BIKE DO SOME OF THE WORK
Today’s motorcycles are good. They have come a long way from the days when the buyer had to finish manufacturing them. Even so, the bike you buy isn’t perfect. It can’t be, because the people who made it don’t know you. They don’t know if you weigh 120 pounds or 250 pounds. They don’t know if you ride supercross or outdoors. They don’t know if you race or play-ride.
Getting your suspension dialed in for your riding style is the first priority after getting a new bike, and proper setup is an ongoing process–just because your bike worked well for you last week on one track, don’t assume it’s going to be perfect forever. Never stop testing and thinking about what your bike is doing. These are some brief tips on how to make your suspension as good as it can be.
There is a tendency for manufacturers to underspring their forks. This hasn’t been as bad in recent years as it was earlier, but it still happens. Unless you are an absolute featherweight, it’s unlikely that you will need to use lighter fork springs than stock. For most types of racing, it’s much more likely that you will have to find heavier springs–especially if you weigh over 145 pounds (for a 125) or 16S pounds (for a 250 or 500). Riders who race in supercross, mud or sand can also benefit from stiffer springs.
In the rear, it isn’t as likely that you will have to increase spring rates. Some riders actually do go to softer rear shock springs. More than likely, though, you can get away with what came stock–rear suspension isn’t quite as finicky as front suspension, plus you have more adjustability.
To get a starting point, go to your favorite track and set the rear suspension up with 100mm of sag–that’s the difference between the seat height (taken at the rear) with the suspension fully extended and compressed with your weight. Start off with the clickers in the standard positions, then go testing. Pay attention.
PROBLEMS & SOLUTIONS
If the fork bottoms: (1) Increase the compression damping. Go two clicks at a time. (2) If that makes the suspension feel harsh and doesn’t cure the problem, increase the oil level in 5mm increments. Don’t go higher than it allows in your manual. (3) If the fork still bottoms, try the next-heavier spring, reduce the oil level and start over.
If you have headshake: (1) Be sure the fork isn’t abnormally soft and doesn’t bottom. If it is, go through the steps outlined above. (2) Reduce the rebound damping. (3) Check to be sure there is a slight amount of drag in the steering head bearings (very slight).
If the front knifes or oversteers: (1) If the fork isn’t bottoming, reduce the oil level and go up on spring rate. This will raise the front end during braking. (2) Try more rebound damping in the rear shock. (3) Decrease the rear shock preload. (4) If all else fails, try sliding the fork tube down in the clamps. Don’t go more than 5mm.
If the bike doesn’t want to turn: (1) Try increasing the rear shock preload. Don’t go under 90mm of sag. (2) If the rear end isn’t too stiff, increase the compression damping two clicks at a time. (3) If you have no trouble with headshake, increase the fork’s rebound damping two clicks at a time. (4) If you have no trouble with fork bottoming, decrease the fork’s compression damping two clicks at a time. (5) If you can, try reducing the fork preload by a maximum of 5mm. (6) Try a softer spring as a last resort.
If the rear end doesn’t hook up: (1) Recheck the rear suspension sag. Not enough preload can cause this. (2) Reduce the rear shock’s rebound damping. This allows the rear wheel to get on the ground faster and should increase traction. (3) Check the rear axle position. If it has been adjusted all the way rearward, then shorten or replace the chain.
If the rear end kicks while braking: (1) A common mistake is to increase rear shock rebound damping. Usually faster (reduced) rebound damping is the cure. (2) Have a friend watch your rear wheel to see if it is extending when it leaves the ground so you can determine if the rebound is too fast or too slow.
If you can’t take the whoops: (1) Try increasing rear compression damping. (2) Increase rebound damping, but not so much that the rear suspension “packs” in repeated bumps.
If the rear end bottoms: (1) Increase compression damping. (2) Increase spring preload (again, don’t go under 90mm or 95mm of sag). (3) Decrease rebound damping. (4) Try a stiffer spring. Any time you reach the outer limit of adjusting, whether it’s compression damping or preload, be suspicious. You might be misdiagnosing the problem or there might be a mechanical problem. There are a variety of things that could go wrong, from leaky fork seals to broken springs. Make sure your bike isn’t trying to tell you that something is wrong.