A shock absorber is a device that works by converting mechanical energy into heat. It damps oscillations and absorbs the jolts and impacts acting on the body. Its main job is to keep the wheels in contact with the road while riding, as well as when accelerating and braking. Shock absorbers are used in aircraft and automotive engineering. They are classified as friction, hydraulic, gas, combined, single-acting and double-acting. Friction shock absorbers damp oscillations, and their distinctive feature is that their resistance does not depend on how fast the rod moves. Hydraulic shock absorbers are the most common type today. What sets them apart is that their resistance force depends on the speed of the rod.
Hydraulic shock absorbers most often use a twin-tube design. In gas shock absorbers the working medium is gas, while combined shock absorbers can use both oil and gas. A single-acting shock absorber works in one direction: when the rod moves one way, it works, and when it moves the other way, it doesn't. A double-acting shock absorber works in both directions, as the rod moves either way.
Scooters usually use single-acting oil shock absorbers or double-acting gas-oil shock absorbers, combined with a spring. Quality gas-oil shocks, in addition to spring stiffness adjustment, have a so-called "pump-up" feature that adjusts the performance of the shock absorber itself depending on the weight. When choosing a scooter shock absorber, pay attention to the spring stiffness. It determines how well your scooter will "get along" with a bumpy road and respond to steering.
Some riders prefer soft springs because they make the scooter more compliant in corners. If you can't decide, the ideal choice for you is a scooter shock absorber with adjustable spring stiffness. The country of manufacture also matters. European shock absorbers wear out quickly on our roads, so Japanese- or Chinese-made shocks designed specifically for rough roads suit us better.
It's also important to pay attention to the packaging and identifying marks. If a shock absorber has no markings at all, even if it's Chinese, you are most likely looking at a Chinese fake. But if the name and other markings are applied neatly and evenly on the box and on the shock absorber, then such a shock, even though it's Chinese, will serve your scooter well.