Compression damping assists a spring in resisting bumps and loads placed on the motorcycle, which is generated in upward wheel motion. This kind of damping changes the rate at which the wheel is allowed to travel upward relative to the chassis.
Rebound is the opposite of compression damping. After the wheel has hit a bump, the spring forces the suspension and wheel back toward the ground. Rebound damping controls the rate at which the wheel is allowed to extend.
Many modern suspension components offer low-speed and high-speed compression damping. The terms “low-speed” and “high-speed” can be confusing as they do not refer to the speed of the motorcycle. Rather, the terms refer to the speed at which the suspension is moving. Low-speed damping adjustments are used to ensure the bike is stable over gentle undulations in the road surface. High-speed damping deals with sharper variations in road surfaces and when the bike transitions from heavy acceleration to heavy braking or vice versa.
Preload and Sag:
Motorcycle suspensions are designed so that the springs are always under compression, even when fully extended. Pre-load is used to adjust the position of the suspension with the weight of the motorcycle and rider acting upon it. Both the front forks and the rear shock can be adjusted for spring pre-load on most modern motorcycles. Given an acceptable spring rate and after adjusting preload, the amount of “sag” for a given rider’s weight, motorcycle weight and suspension friction can be attained.
Were you aware that something as simple as changing tire brands could alter the geometry of your motorcycle? The rake and trail values of your motorcycle play a major role in it’s handling characteristics. Even small changes can dramatically effect the way your bike feels. Some sport bikes require geometry changes to acheive maximum performance.