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Suspension Setup Guide
We take a look at suspension setup routines and how you can dial in your bike's suspension.From the November, 2009 issue of Sport RiderBy Andrew Trevitt
One common misconception is that there is some magical setting that will work for every rider in every situation (and we'll be the first to admit that our suggested settings are not that wonderful setup, but rather a starting point). But that certainly is wishful thinking. Tires, your riding style, where you ride, the condition of your suspension and rider weight and ability all play a part in finding optimum settings. The setup you (or we) find may be completely off base for someone else. As enigmatic as the optimum suspension setup may seem, this guide sums up the important parts in five easy steps that will help you get the most from your bike.
Before you begin dialing in your boingers, make sure your shock, fork and the rest of your bike are in decent shape. Your tires should have plenty of tread and should not be squared off, and of course you check their pressure religiously, right? Ensure that your fork and shock seals are still holding oil, and that the shock's linkage is not binding or sloppy. Your steering-head bearings should be in good shape and properly torqued. A sloppy or too-tight chain will make even the newest bike with a perfect setup feel horrid. And if you've had a tip-over, have your bike and its components checked for straightness.
When dealing with suspension, it is vital to work in a methodical manner, much as you would with any experiment. Begin with a known base line, work in increments making one change at a time and take copious notes so you can always revert to that base line if you've gone astray. Arm yourself with the basic tools needed to adjust your suspension (usually what's in the tool kit will suffice), a tape measure and some patience, and let's get started.
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DEFINITIONS
Knowing what does what
While the more familiar you are with the insides of your fork and shock the better, it's not imperative to know every last detail and technical term related to suspension and handling. Instead, concentrate on learning what each adjustment does-not just the mechanics of it, but what you can expect to feel as a change in your bike when you twiddle that knob. Read your manual to find out what adjustments your bike has and where they are (sometimes they're well-hidden).
Preload: This adjuster bears down on the shock or fork spring and shortens or extends the spring accordingly. Many people think that changing preload affects spring stiffness, and while you can compensate to a certain extent for a too-soft or too-stiff spring by using preload, the right move in that situation is to change the spring itself. Preload is used to adjust the shock or spring to the correct range of operation within the suspension's travel-more preload will raise the bike up on its suspension, keeping you near the top of its travel. With less preload, the bike sits lower and closer to the bottom of its suspension travel.
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Rebound damping: Once your suspension has compressed over a bump, rebound damping determines how fast the suspension can extend and keep the wheel in contact with the ground. Too much rebound damping will keep the suspension compressed when it should be extending to follow the road on the downside of a bump, and the wheel will lose contact with the ground. Too little rebound damping and the suspension will extend fast enough to push the bike up forcibly, giving it a loose feeling. Because rebound damping plays such a big part in how well the tire stays in touch with the ground, it gives you the feeling of traction and the confidence that comes with it.
Trail: Technically speaking, trail is a horizontal measurement from an imaginary point where a line through your bike's steering head meets the ground and then back to the front tire's contact patch. This measurement is important for general handling because trail determines steering quickness and stability. Less trail will quicken steering but sacrifice stability, while more trail will make steering heavy but add stability. You can change trail by using a front tire of a larger or smaller diameter, triple clamps with different offsets or by altering chassis attitude using ride height.
Ride height: Consider your bike as just a frame and subframe hanging in space. Ride height is a measure of how high the steering head (front) and subframe (rear) are above the ground, and juggling front and rear ride heights will change your bike's geometry. Tipping the bike forward with less front ride height will reduce rake and, more importantly, trail. This will quicken your bike's steering, but reduce stability. Raising the front of the bike or lowering the rear will lengthen trail, slowing steering but benefiting stability. You can change front ride height by moving the forks in the triple clamps, and rear ride height can be altered by lengthening or shortening the shock.
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