Originally Posted by aardvarkcycles

Air/Oil Shocks, aka air shocks, aka pneumatic shocks, aka gas shocks, all work on the same principle. An air chamber is pumped with air. This air chamber works just like an invisible elastomer and provides the resistance the shock has when you land that gnarly jump. The oil part is for damping the rebound so your wheel doesn't snap back out so fast you wipe it in front of your riding buds. There are numerous variations on this concept, with different valving, different chamber setups, etc.

The advantages of air/oil shocks are that they are light weight and almost infinitely adjustable. On the downside, they tend to be a little harsh on the small stuff. There is a certain amount of force needed to get the shock in motion, so your butt can be feeling some chatter, but these hits might too soft for the shock to "notice" and you'll feel like your riding a hardtail again. Newer shock design incorporating negative springs avoid much of this problem. These shocks also require air pressure, so that means you need a special high psi air pump. The internals on these things are very complex, and should only be worked on by the manufacturer or a highly skilled mechanic.

Air/Air Shocks Fox, Rock Shox, and Cane Creek are making excellent shocks that uses air chambers for both the resistance and damping, which is super lightweight and very tunable. The big advantage is how lightweight they are, but they can suffer from the same low impact harshness as Air/Oil shocks..

Coil Spring Shocks replace the air chamber with a big spring to provide the resistance. Oil is used to damp the rebound. These shocks offer superb small bump sensitivity, with sidewalk cracks often enough to get these things going, yet the progressive nature of steel springs handle the big bumps great. Coil-spring shocks also offer simplicity, low maintenance, and relatively inexpensive price tags.

Sounds too good to be true? Well, the negative aspects are weight, weight, and more weight. These will weight as much as a full pound more than a good Air/Oil shock. Titanium springs are being offered as a replacement for the stock steel springs, but in our opinion, there have not been any decent springs on the market worth buying. Ti has different characteristics than steel and doesn't seem to make a very reliable spring from what we have seen so far.

What Should You Get? Think about what type of riding you do, what you want your bike to act like, and how much money you have to spend. This is I can tell you, no matter which shock you buy, time invested in proper intallation and tuning to match your rider weight and riding style will pay huge dividends in enjoyment.. In most cases, you cant just bolt on a new shock, you must tune it to the travel and spring rate of your bike. This is something you must do yourself, it can't be done via email! Properly tuning a shock to your rider weight, style of riding, and suspension design is essential.