A coil spring (wound steel coil) provides a linear compression rate, giving smooth, consistent impact absorption over the range of spring travel. Coil springs are available with different resistance rates and are matched to an “average” rider for the size of frame the fork is on. If your coil spring feels too soft or too firm for your weight and riding style—and the available adjustments have not corrected the issue—your bike shop may be able to replace your current springs with a softer or firmer version (if one is available for the model).

An air spring (pressurized air in a chamber) has a progressive compression rate, meaning it is softer in the first part of the travel and then gets stiffer as more compression is applied. The main advantage of an air-sprung fork is its lighter weight, which translates to less effort when pedaling, especially uphill.

Air sprung forks save weight and offer more adjustability. Air sprung forks are infinitely adjustable for all rider weights. It's a matter of attaching a shock pump to the air valve and pumping away. Shock pumps are usually supplied with the fork - but not always.

Metal coil springs are found on cheaper forks and on a lot of Downhill forks (where weight isn't so much of an issue). Coil springs aren't very adjustable for different rider weights. If you’re beyond the weight range of the supplied coil then you have to buy another coil that is suited to your weight.

Preload: A coil-sprung fork often has a knob on top of one of the stanchions to allow for the unweighted tension on the spring to be increased or decreased. Increase the preload if the fork feels too spongy.

pressure: An air-sprung fork does not have a preload knob; instead it has a Schrader valve for adjusting the air pressure, and therefore firmness, of the fork. A special “shock pump” is needed for this; do not use a regular tire pump. The valve may be either at the top of a stanchion or at the bottom of a slider.

Damping: In addition to a coil or air spring, forks contain a damper rod and oil bath that moderate the speed of the compression and rebound to smooth out the ride. Adjustments may be available for both the compression and rebound. Adjusting damping settings are referred to as “tuning the fork.” Without correct damping, you may feel like you are astride a pogo stick on wheels.

Compression damping controls how quickly the spring absorbs an impact.Rebound damping controls the speed at which the fork re-extends after compression. This reduces overly fast bounce-back.