There are several different styles of mountain biking,
usually defined by the terrain, and therefore bikes employed. Styles of
mountain bike riding and mountain bikes have evolved rapidly in recent years
leading to terms such as Freeride and "Trail bike" being used to
categorise mountain bikes. Definitions for the most widely used terms are
listed below.
Cross country (XC)
:
Cross country mountain bikes are designed primarily around the discipline of
cross country racing. Cross country racing with its emphasis on climbing as
well as speed and endurance demands bikes that are both lightweight and
efficient. In the 1980s and early 1990s XC mountain bikes typically consisted
of a lightweight steel hardtail frame with rigid forks. Throughout the 1990s XC
bikes evolved to incorporate lightweight aluminium frames and short travel (65
to 110 mm) front suspension forks. Recently full suspension designs have become
more prevalent, and the use of advanced carbon fiber composites has allowed
bike designers to produce full suspension designs under 10 kg. The geometry of
Cross Country bikes favours climbing ability and fast responses over descending
and stability and as a result typical head angles are 70–71°. Although intended
for off-road use, Cross Country mountain bikes with their emphasis on
lightweight construction are not designed for use on the most steep or severe
terrain.
Trail Bike: TrailBikes are a development of XC bikes that are generally used by recreational
mountain bikers either at purpose built "Trail centers" or on natural
off-road trails. They usually have around 5" (120–140 mm) of travel, weigh
11 to 15 kilograms (24 to 33 lb), and have geometries slightly slacker than XC
bikes, though not as slack as AM bikes. Examples include the Giant Trance, the
Trek Fuel EX series, the Specialized Stumpjumper FSR, and others. With less of
an emphasis on weight, Trail Bikes are typically built to handle rougher
terrain than dedicated XC bikes while having slacker head angles (69-68°) which
provides greater stability while descending.
Enduro/all-mountain
(AM) bikes: Enduro/all-mountain bikes bridge the gap between cross-country
and freeride bikes, such as the Trek Remedy series, Specialized enduro,
typically weighing between 13 to 16 kilograms (29 to 35 lb). These bikes tend
to feature greater suspension travel, frequently as much as 6 inches (150 mm)
or 7" of front and rear travel, often adjustable on newer mid- and
high-end bikes. They are designed to be able to climb and descend well, these
bikes are intended to be ridden on all-day rides involving steep climbs and steep
descents, hence the term 'all-mountain'.
Downhill (DH) bikes:
Downhill bikes typically have eight or more inches (200 mm) of suspension
travel. They are built with frames that are strong, yet light, which often
requires the use of more expensive alloys and very recently, carbon fiber. In
the past few years, lighter downhill bikes have been getting below the 40 lbs
mark (18 kg). Due to their typically large or high gears, long, plush travel
and slack geometry angles,
Downhill bikes are ideal only for riding down
dedicated downhill trails and race courses. Downhill bikes have the most sag of
Mountain Bikes to get ample traction to go fast over bumpy trails. Head Angles
are often as slack as 63 degrees. Several types of bicycle speed records have
been registered downhill. Due to the high-speed nature of downhill riding most
bikes only have one chain ring in the front, a large bash guard and a chain
guide, though many racers are now using chain guides without bash guards to
reduce weight. Some manufacturers have experimented with designs featuring
internal gearboxes built directly into the frame construction. This
modification eliminates the need for the rear dérailleur mechanism but has not
been embraced due to durability issues with the gearbox during the stresses of
a DH race.
Freeride (FR)
mountain bikes: Freeride mountain bikes are similar to downhill bikes, but
with less emphasis on weight and more on strength. Freeride bikes tend to have
ample suspension and typically have at least 7 inches (180 mm) of travel. The
components are built from stronger, consequently heavier, materials. They can
be ridden uphill, but are inefficient and their moderately slack head tube
angles make them difficult to maneuver while angled up a hill or traveling at a
low speed. They are effective on technical downhill trails. Frame angles are
typically steeper than those found in downhill bikes. This enhances
maneuverability over and around small objects. Freeride bikes typically range
in weight from 14 to 20 kilograms (31 to 44 lb). The most durable freeride
bikes are often too heavy and have too much suspension to be ridden uphill as comfortably
as other less-sturdy models, although newer, more expensive bikes come with
suspension specifically designed to make them easier to ride uphill.
Trials bike: Trials
bikes are set up very specifically for the purpose of bicycle trials. Two
varieties of trials bike exist, those with 26" wheels (referred to as
'stock') and those with 20" wheels (referred to as 'mod' - because
historically they were modified BMX bikes). They typically have no suspension
at all, though some still make use of some form of it. Competition rules
require stock bikes to have multiple gears for competition, but most riders
never use their shifters. Competition rules do not require mod bikes to have
any gears. Many non-competitive riders run single-speed, choosing a fairly
low-speed, high-torque gear. Most modern trials bikes have no seat at all, as
the rider spends all of his time out of the saddle. These bikes are
significantly lighter than almost all other mountain bikes, ranging from 7 to
11 kilograms (15 to 24 lb). This makes maneuvering the bike much easier.
Dirt jumping, urban
and street mountain bike: Dirt jumping, urban and street mountain bikes lie
somewhere in between a BMX bike and a freeride bike. They are typically very
strong bikes, with 4 to 6 inches (100 to 150 mm) of front suspension, and
rarely any rear suspension (3 to 4 inches, 76 to 100 mm, if any), with as many
as nine gears or as few as one. Tires on these bikes are usually fast-rolling,
slick or semi-slicks. Dirt Jumpers usually sport a geometry of 24-26"
tires, as well as a bashring (a type of bashguard) replacing the largest ring
on the crankset. Dirt jumpers usually have low seatposts and oversized
handlebars. Most dirt jumpers have an extended rear brake cable installed and
have no front brake, which allows the rider to spin the handle bars without
tangling the brake cables.
Single-speed (SS)
mountain bike: Single-speed (SS) mountain bikes have one set gear ratio.
The gear ratio chosen depends on the terrain being ridden, the strength and
skill of the rider, and the size of the bike (a bike with 29" wheels often
requires a different gearing than a bike with standard 26" wheels). Often
single-speeds are fully rigid, steel-framed bikes. These are typically ridden
by very fit individuals on mild to moderate cross country terrain.
Mountain cross or "Four-cross" (4X) is a
relatively new style of riding where four bikers race downhill on a prepared,
BMX like, track, simply trying to get down first. These bikes are generally
either full suspension with 3 to 4 inches (76 to 100 mm) of travel, or
hardtails, and have, typically, quite strong frames. They run a chainguide on
front and gears on the back. They have slack head angles, short chainstays and
low bottom brackets to aid in cornering and acceleration.
Dual slalom (DS) is similar to Four-cross, but instead of
four competing cyclists during a race, there are only two. Courses usually have
a lane for each rider, though some combine to a single lane in places or even
for much of the course. The courses are in general more technical with smaller
jumps than Four-cross courses. Dual Slalom races originally took place on grass
slopes with gates and minimal jumps, but are now held on man-made courses. Dual
slalom riders will usually use the same bikes that Four-cross riders use.
Indycross (IX) is essentially a Mountain Cross event
featuring a wide variety of features run by one competitor per time.
North Shore bikes are much like freeride bikes in their
geometry and downhill bikes in their component makeup. Because north shore
stunts have evolved to not only include simple and complex bridges but also
large drops and high-speed descents through a series of stunts north shore
bikes commonly have as much travel as downhill and freeride bikes, however with
much more nimble and maneuverable frame designs, and often lighter weight.
Circle dirt track racing In this class of racing any kind of
bikes are used, most commonly a hard tail mountain bike with front suspension.
Many different modifications are made to track racing bikes, such as reducing
bike weight, increasing brake power, trying different cambers (so that when the
bike leans the tire is more level with the track thus creating more grip), and
trying different gear ratios.
It should be noted that in the early days of mountain
biking, all mountain bikes were somewhat custom, home-built machines, and were
used for any number of stunts, tricks, racing or other activities. The general
design of the bikes were similar. As the sport grew, more specialized designs
and equipment were introduced. The further market segmentation beyond simple
front suspension XC began to occur in the mid-1990s, as large bicycle and
equipment manufacturers were able to cater specifically to changing demands.
