Gone are the old days when you only had a few inches of front travel to overcome the roughest and most technical terrain. Luckily, one of the great revolutions of the mountain bike is a longer trip on its fork. Big wheel mongoose bike is providing stable balance for its flat tire and forks.
Without a doubt, this is a fundamental part of the enduro discipline since it helps us when it comes to overcoming certain obstacles, roots, rocks and steps, and correcting our mistakes.
A fork is made up of the head tube, plate (or crown), bars, bridge, and bottles. We will also have some adjustment dials that will generally be more complete if the investment is greater.
Suspension fork construction
According to the situation of the bars, we can find two types:
Classic: that of a lifetime, wherever you look, the damping is sure to exist in the upper part of the fork. You have a multitude of models on the market.
Inverted: in this case, the bars in charge of damping are in the lower part of the fork, where it joins the hub. There are hardly a couple of models on the market, so you will have to look exhaustively at the different component purchasing websites if it catches your attention.
There are different coatings for the bars whose function is to minimize friction, improve behavior, and prevent wear. The Kashima is the best known in the biker world for its characteristic golden color. There is also the DLC, TiN… but don’t eat the jar because it doesn’t even come in most of the manufacturer’s spec sheets.
Types of suspension forks
Depending on the system we have inside the bars and bottles, we will have two clearly differentiated families, although physically and externally, they are hardly distinguished.
Air suspension forks
Inside the left bottle of this type of fork, there is an air chamber that compresses or expands when it works. The air chamber is in charge of the damping.
Advantages of air suspension:
- Lighter weight
- Great fit and adaptation to driving
- Disadvantages of air suspension
- Requires more maintenance
- Not so “fine” or soft touch
- They are affected by sudden variations in temperature
- Spring suspension forks
In this type of fork, a spring is introduced inside the left bottle, producing the damping when the piston compresses or pushes the spring.
Advantages of the spring suspension:
- Requires less maintenance
- Touch superior to air, soft, and with great sensitivity
- Unalterable due to sudden variations in temperature
- Disadvantages of spring suspension:
- They are generally heavier
- Less adaptation or adjustment, depending on the hardness of the spring you choose
- Fork steerer tube diameter
To fit the proper fork on your enduro frame, you will need to check whether the head tube supports a straight or tapered head tube. In addition, it is very important to make sure that both the frame size, the fork, and the direction match. For this, we always recommend consulting the manufacturer’s technical information.
The offset or advance of the fork is the distance between the axis of the steering head and the center of the axis of the front wheel. This is another of the measures that, together with the geometry of the bike is important since it considerably influences the behavior of the bicycle. Simply put, offset helps balance maneuverability and stability.
A higher offset increases the wheelbase, which slows the center of gravity, improves front wheel handling and the handling is more “edgy.”
A lower offset advances the center of gravity by loading more weight in front. As a result, the behavior is more stable at high speeds and in a straight line but is less agile at low speeds.
Check the specifications and recommendations of both the frame and fork manufacturer to make your decision correct.
Fox 38 suspension
The market has been increasing the diameter of the bottles to reach ranges from 35 to 38 mm (although they will soon launch a new fork with 39 mm). A larger diameter increases the stiffness and theoretically flexes less, which helps to turn with greater precision and also obtain more resistance against small impacts.
However, a larger diameter means larger seals, more surface contact, more material, and a larger housing for the oil, so friction is increased and some extra weight is added as well.
Even so, each manufacturer uses different materials, thicknesses, technologies, etc., so these statements must be taken with some suspicion.
The forks are not designed to be used with different tires interchangeably. You should always make sure that the fork is compatible with the size of your wheel.
The same happens with the axis measurement. Always make sure that the measurements of the fork and your axle are compatible. Common measurements are 15 x 100mm (for not-so-new models) and 15 x 110mm (boost), which have become the new norm for enduro bikes due to their increased stiffness.
One of the most important characteristics when choosing an Mtb fork is the travel of the bars. And it is that although they are only a few centimeters, they are of great help to face complicated terrain with greater security.
As with the dimensions that we have already reviewed, the fork travel must be appropriate to the geometry and size of your frame. Depending on the performance you’re looking for, your riding skills, and the type of trails you typically ride, for an enduro bike, you can choose between 140-180mm of travel.
The possibility of adjusting more parameters depends on the quality. A higher range always offers a greater adjustment, being able to have the following:
It is called preload to the necessary pressure that you have to introduce in the main chamber of the fork through the valve located in the upper part of one of the bars. If it is spring, you will have to adjust the necessary tension through the corresponding dial. Look at the manufacturer’s specifications and adjust the pressure or tension to your weight.
The Sag is the difference between the travel at rest and the one subjected to the pressure of your weight. One of the bars usually has a small red rubber ring for easy viewing and even a percentage scale.
Normally for enduro use, it is recommended that it be around 25%. However, you have to take into account the indications of some manufacturers, your personal taste and your driving style, as well as the type of terrain you are moving through. Adjust the preload according to what you need.
Compression [low speed (LSC) and high speed (HSC)]
Most of the forks have a dial on the top of the right bottle to regulate the hardness of the suspension and adapt it to the terrain. The vast majority of forks have dials with two or three positions (general – open, firm, pedal) and can even have two to adjust the behavior during pedaling or for jumps and obstacles.
This operation is usually done from the fork itself, although there are manufacturers and models where it is possible to do it remotely with a lever on the handlebar in a very safe way.
Usually, we will have another dial at the bottom of the right bottle that allows you to adjust the return speed of the tour. You can adjust the bounce by turning the dial a certain number of clicks. We can find two dials in higher range forks to adjust the rebound during pedaling or in jumps and obstacles.
In some models, the fork travel or the sensitivity at the initial stroke can be modified. Other models include a purge button to equalize atmospheric pressure so as not to compromise performance or sensitivity.
As you can see, the world of settings is very wide. Decide if you need all of them and check the manufacturer’s specifications.
Suspension Fork Maintenance
There are a couple of basic maintenance things you should keep in mind, like wiping the dust off the bars with a rag or lubricating the seals from time to time.
It’s a good idea to check your fork pressure regularly. Check your fork manual to find out how many hours you should change the oil, seals, etc. If you have knowledge and skill, go ahead. If not, contact your trusted workshop.