How they guarantee a smooth ride
There are three main types of shock used on bikes. The simplest is an emulsion shock where a volume of nitrogen and damping oil inside the shock body is mixed to give it a viscosity that allows it to flow through valves contained within the shock at the right rate to soak up the energy from a bump.
Next are floating piston designs that keep the nitrogen and oil separate for more consistent performance. Some have a separate reservoir for the nitrogen, either ‘piggy-back’ on the shock body, or mounted remotely with a hose connection for better cooling.
Finally, there’s the twin tube
shock design, pioneered by Öhlins, which keeps the oil cooler for more consistent performance. Instead of a piston running up and down the shock body with a shim stack to control the damping rate, you have a solid plunger with two tubes, one inside the other, with bypass holes at each end. The plunger pushes a slug of oil through valve housings inside the shock body, which have either shim stacks or needle bypasses for adjustment. From there it flows around the outside of the tube to the other side of the plunger, then as the shaft comes out of the shock body it pulls the oil back the other way.
Remote adjusters make for easy set-up changes
Depending on the linkage, the spring rate can be linear or progressive 1 2 3