Been hearing alot of suspension questions lately and thought id put this up here. We put it together on my local forum, its basically a compilation of others materials all put together for just about anything you need to know suspension related.
i havent read through this in awhile so if there is anything to add or edit post up!
Dan Kyle thread
Jamboy/Sport Rider thread
onthethrottle.com - Setting Sag is the first order of Suspension Business
To ride like a pro you've got to talk like one
Every activity has its own language. Learning a new skill sometimes feels as if it requires scaling a linguistic learning curve that makes surmounting Mt. Everest seem like a day hike. To the uninitiated--not that any Sport Rider reader could be accused of this--the language of motorcyclists can seem just as daunting. So, to make sure we're all standing on top of the same hill, peruse the terminology below to help speed yourself along to suspension enlightenment.
(also called bottoming out)--when a suspension component reaches the end of its travel under compression. Bottoming is the opposite of topping out. Cartridge Fork--a sophisticated type of fork that forces oil through bending shims mounted to the face of damping pistons contained within the fork body. The primary advantage of cartridge forks is they are less progressive than damping rod forks. The shims allow damping control at very low suspension speeds while high speeds deflect the shims more--causing less high-speed damping than fixed orifice damping rods. The resulting ride is firmer with less dive under braking while simultaneously lessening the amount of force square-edged bumps transfer to the chassis.
--controls the initial "bump stroke" of the suspension. As the wheel is forced upward by the bump, the compression circuit controls the speed at which the suspension compresses, helping to keep the spring from allowing an excessive amount of travel or bottoming of the suspension. Damping--viscous friction caused by forcing a fluid through some type of restriction. Damping force is determined by the speed of the fluid movement, not the distance of suspension travel.
Damping Rod Fork
--a simple type of fork that utilizes a tube with holes in it to create compression and rebound damping, delivering an extremely progressive damping curve. The faster the wheel moves vertically, the more oil that is shoved through the holes. Typically, damping rod forks have very little low-speed damping and a great deal of high-speed damping. The ride is characterized by excessive fork dive under braking and hydraulic lock when encountering square-edged bumps. Any change to the damping rod system, such as changing the size of the holes or altering the oil viscosity, affects the entire speed range.
Fork Oil Level
--the level of oil within the fork as measured when fully compressed without the spring installed. It is used in tuning the amount of air contained inside the fork. Since compressing air makes it act as a spring, raising the oil level leaves less room for air, resulting in a rising rate throughout the fork's travel. Reducing the oil level reduces the force at the bottom, giving a more linear rate.
--the amount the bike settles under its own weight. Both streetbikes and race bikes require 0 to 5mm of free sag on the rear. The bike should not top out hard.
--damping to control fast vertical movements of suspension components caused by road characteristics such as square-edged bumps. High-Speed damping is independent of motorcycle speed.
--damping to control slow vertical suspension movements such as those caused by ripples in pavement. (This is also independent of motorcycle speed.)
The fork rebound adjuster, like all the damping controls, screws in for firmer and out for softer.
Problem: Terry's bike feels unstable, especially when entering turns. The bars seem to "twitch" excessively whenever a midcorner bump is encountered. The bars often whip back and forth violently several times (or more) when Terry is accelerating aggressively over bumps while coming out of a turn--in other words, a "tankslapper." The bike steers very easily, although a lack of traction is sometimes noticeable in the rear whenever he tries to accelerate at moderate lean angles. The bike also seems to have a dropped-down, "nose low, rear-end-high" attitude while riding.
Solution: The biggest distinguishing factor in this case is the "nose-low/rear-end-high" chassis attitude feeling. If Terry's bike definitely feels this way, then probably he has too much front end weight bias. This not only hinders traction at the rear, but also affects the steering geometry (steeper rake/less trail) and can cause the instability problems. As long as Terry has his suspension static sag levels set correctly, the first step is to try less rear spring preload and/or more front preload, to the point just before they begin to affect handling negatively; Terry should remember to adjust his rebound damping if necessary (in fact, he should check to see if decreasing the front rebound damping in small increments helps; the forks may be too stiff, hindering traction). If only partially successful, a more drastic step would be changing chassis ride height; this would involve raising the front end by dropping the fork tubes in the triple clamps (if there's enough material protruding above the top clamp, to ensure front fork structural integrity), and/or dropping the rear by shortening the rear shock (if possible).
Note: We've also seen a tankslapping tendency produced by too much rearward weight bias. Terry might try working the opposite of the preceding paragraph solution, or check out the understeer/no front traction problem scenario for more suggestions.