|If you want to keep your front wheel on the ground and remain in control over technical terrain, then a suspension fork is a good thing to have. Forks are built to handle certain kinds of terrain and riding styles based on the rider's needs. Use the comparison tool to help sort out which fork is right for you.|
XC forks are built to be lighter and more adept at moving fast over moderate terrain.
AM forks are the jack of all trades; while they might not excel at any one style, they are pretty darn good anywhere on the mountain.
FR forks are built for going big. If you're hucking off a jump or practicing for a trails comp, this is the fork for you.
DH forks are the Hummers of the MTB world... and not those new wussy, "I don't like the outdoors, but I need something really big to haul my kids around" Hummers... but the badass, no thrills, "I eat rocks and mud for breakfast and get out of my way or you'll be flattened" Hummers. If you think wearing body armor is just another part of the ride, then these are for you.
A bicycle fork is the portion of a bicycle that holds the front wheel
and allows the rider to steer. A fork consists of two dropouts
that hold the front wheel axle,
that join at a fork crown, and a steerer or steering tube to which the handlebars
attach allowing the rider to steer the bicycle. The steerer of the fork interfaces with the frame
via a set of bearings known as a headset.
On most mountain bicycles
the fork contains a set of shock absorbers. The suspension travel
and handling characteristics vary depending on the type of mountain biking the fork is designed for. For instance, manufacturers produce different forks for cross-country (XC), downhill,
and freeride riding.
The shock absorber usually consists of two parts: a spring and a damper or dashpot. A damper is a device which resists motion via viscous friction within a fluid. A dashpot is a type of hydraulic/mechanical damper.
The spring may be implemented with a steel coil, an elastomer, or even compressed air. The damper is usually implemented by forcing oil to pass through a small opening. On some models, the spring, the damper, or both may be adjusted for rider weight, riding style, terrain, or any combination of these or other factors. The two components may be separated with the spring in one blade
and the damper in the other.
Some manufacturers, especially Cannondale, have tried other variations including a single shock built into the steering tube above the crown and a fork with just a single blade
that has a shock built into it.
Bicycle forks usually have an offset, or rake, that places the dropouts
forward of the steering axis. This occurs in mountain bikes
typically by angling straight blades
forward, and, in addition, the dropouts
are often mounted forward of the centerline of the blades
increasing the rake as well.
The purpose of this offset is to reduce 'trail', which is the distance that the front wheel
ground contact point trails behind the point where the steering axis intersects the ground. Too much trail makes a bicycle feel difficult to turn. Increasing offset results in decreased trail, while decreasing offset results in increased trail.
When determining the offset/rake on a mountain bike,
the frame's head angle and wheel
size must be taken into account. There is a narrow range of acceptable offsets that give good handling characteristics. The general rule is that a slacker head angle requires a fork with more offset, and small wheels
require less offset than large wheels.
When sizing a fork to a frame,
be sure to know the diameter of the fork steerer or steer tube. Mountain bike
steer tubes can be 1", 1 1/8", 1 1/4" or 1 1/2" (often called OnePointFive) in diameter. Most manufacturers are more than generous with the length of their steer tubes, so much so, that the tube often needs to be cut down substantially to a length that is approximately equal to the head tube
length plus the stack height of the headset.
of course, must be long enough to accommodate the desired wheel
which may be either a 26" or 29" in diameter.
Fork steer tubes may be threaded or unthreaded depending on the headset
used to attach the fork to the rest of the bicycle frame.
An unthreaded steel steer tube may be threaded with an appropriate die if necessary. More information can be found in the headset
Forks may have attachment points for brakes,
racks, and fenders. These may be located in the crown, along the blades,
and near the dropouts.
These are often holes, threaded or not, and may be located on tabs that protrude. Make sure that whatever fork you get is compatible with the brakes
that you want as some forks have either brake
bosses for rim brakes
or tabs for disc brakes,
while others have both.