Today we write about one of the most ignored and neglected system on most motorcycles. As long as it's working it's invisible. At the most it's modified by lowering the motorcycle and that's the extent of it. Most motorcycles don't get any service to the suspension until it's no longer working. And that is a shame because proper suspension is so important to maintaining control not to mention comfort.
In short the suspension's job is to keep the wheels in contact with the road surface. It does that by a spring and damping. The spring absorbs the irregularities and damping controls the spring. We've all been in a car that had bad shocks. Hit a bump and the car just continues to bounce for some time after the bump is over. That's what damping is supposed to control. Damping uses a couple types of control. The most basic is damping rod, that is a hollow rod that has several holes in it that the oil is forced through when a bump is encountered. The size of the hole and viscosity of the fluid determines the amount of damping. That's the oil's primary job. Secondary is lubrication of the sliding element of forks/shock. The more complicated type of damping is progressive, adjustable and is called cartridge. A piston with large holes backed up by washers (shims) of varying thickness and diameter used to tailor the rates to a given usage. Shocks are similar but vary a little from the basics.
The most important thing is to maintain and replace worn parts. Most shocks are un-serviceable and should just be replaced when the time arrives. Front forks are serviceable and often upgradeable without replacement. All that being forced though small holes under pressure is hard on oil. It creates a good deal of heat along with the debris from sliding elements degrades the oil pretty fast. Some manufacturers are recommending extended service intervals for forks. All that's going to do is sell more bushing and seals as the worn out oil allows parts to deteriorate. False economy. I recommend changing every 17,000 kilometers with the right grade of fork oil. Some use ATF but fork oil has an unusual job and is made for it. Your choice.
If you want to get the nice ride and good handling if you prefer the backroads over slabs an upgrade is possibly in order. Shocks are simple. Buy a good shock that suits your improvement goals. Spend the extra cash and you'll get a nice warranty as well as quality parts that may be rebuildable thus barring damage a lifetime purchase. Forks can go two ways.
One is called a cartridge emulator, it is an add-on valve that imitates the cartridge style fork in progression and adjustability. Some minor machining work is needed to the damping rod and adjusting them is a bit involved but it's only labor not parts.
The second type of fork is called a monotube and is a large gas charged cartridge that replaces the damping rod. It is sealed and carries it's fluid inside with the nitrogen. Serious high-tech upgrade. Nose dive under braking is reduced and small as well as large bump absorption is improved. Monotube upgrade forks aren't cheap bt they carry a limited lifetime warranty.