Mountain Bike Forks - Air v Coil

November 26, 2008 by storeman

When you take riding seriously, the types of forks that you use on your bike can make all the difference in the world for the comfort, function, and reliability of your ride. The purpose of suspension forks is to buffer the wheels movement when hitting bumps, so the wheel will give way without the entire bike moving, creating a bumpy, uncomfortable, and exhausting ride for the rider. The prevention from the jarring effect of bumps also helps protect the integrity of the bike, keeping the need for maintenance lower.

When opting to get new forks for your bicycle, you have two main choices to compare and consider air-sprung and coil-sprung forks.

An air-spring fork is the simplest of fork mechanisms. The fork spring system is comprised of a sealed air chamber. When the bicycle hits a bump or variation in the riding surface, the air within the chamber compresses. The air will automatically seek out a more natural distribution and will force the chamber back into the fully extended position as soon as the pressure of the bump goes away. This will cause the rider to be minimally affected by the variation in the riding surface.

Benefits of the air-sprung forks are:

they are much lighter than their coil-sprung alternatives. Reducing the weight of the forks of course also reduces the weight of the bike. The lighter the bicycle, the less effort, and energy will be required of the rider.
the forks are easily adjustable to work optimally with the rider’s weight and riding style. The adjustment is made by adding or removing air from the air chamber with the use of a special pump.
the air spring forks are progressive in that the further you compress them, the more difficult they are to compress further. A degree of progression is desirable to an extent while riding.
they often have a negative spring incorporated into their system. As the additional spring works in opposition to the main spring, static friction created by the tighter seals required by air-sprung forks is easier to overcome.

The negative side of air-sprung coils is

they are more expensive than coil sprung-coils.
tighter seals are required to sustain the needed air pressure, causing stiffer fork action

For a more versatile fork option which will accommodate a variety of mountain bike riding styles, coil-sprung forks could be a better choice for you, especially if you tend to have a more free-ride or downhill riding style.

The primary advantages of coil-sprung forks are

they are generally less expensive than air-sprung forks. If you are harder on a bike and often risk damaging your forks, this might be an ideal way to save money on replacements.
they are consistent in their operation.
they do not have the problem with failure due to leaking that air-sprung coils can experience.
they are more durable and reliable.

The disadvantage of coil-sprung forks is

they cannot be adjusted to your riding style and weight without changing out the springs.
they are heavier than air-sprung forks, causing more energy to be expended while riding, and decreased maneuverability while riding.
they are linear in operation unless they have been specially designed to be progressive.

There are a vast array of different fork styles and grades of both air-sprung and coil-sprung forks. The technology is advancing constantly, so check with other riders and experts within the field for direction in choosing forks. It is also wise to look for testimonials and ratings of any fork you are considering via the Internet.

The choice of fork for your bicycle is an important decision, as it will have a strong effect on the performance. Choose wisely and enjoy!