A mountain bike, mountain bicycle or ATB (All Terrain
Bicycle) is a bicycle designed for off-road riding, either
on dirt trails or other unpaved environments; in contrast,
road bicycles aren't rugged enough for such terrain.
Mountain bikes have fat, knobbly tires for extra traction.
In recent years front suspension has become the norm and
full front and rear suspension suspension is becoming
increasingly common. Some mountain bikes are also fitted
with bar ends on the handlebars, but with a recent trend
in riser handlebars (as opposed to a flat straight handlebar)
fewer riders use bar end extensions. The bikes normally
have 26 in (660 mm) wheels although since 2002, some models
have been available with 29 in (737 mm) wheels. The larger
wheels supposedly roll better over obstacles but this
comes at the expense of less manoeuvrability and significant
uptake is stymied by the limited selection of tyres and
forks on offer.
There are newer Mountain bikes with either 24 or 27 speed
derailleur gears. In French a mountain bike is called
a VTT (vélo tout-terrain: "all-terrain bicycle").
Freeriding on a Hardtail freeride bicycleMountain bikes
can be classified into three categories based on suspension:
Rigid - no suspension Hardtail - front
suspension fork, no rear suspension Dual or Full suspension
- front suspension fork and rear suspension integrated
into the frame Designs vary to reflect the challenges
of the different disciplines in mountain biking:
Cross Country (XC) Mountain Bikes tend to have only a
small amount of suspension (usually 80-100 mm) on the
front and rear, and weigh comparatively little. This is
achieved through the use of lightweight materials and
suspension is typically provided by metal coil or air
shocks. XC bikes can weigh as little as 20 pounds (9 kg),
up to around 30 pounds (14 kg).
Enduro (or "All-Mountain") Bikes are generally heavier
than XC bikes at between 30 and 35 pounds (14 to 16 kg),
and have more suspension travel, between 100 and 150 mm
of front and rear travel. They are designed to be able
to ascend and descend the mountains, integrating some
of the lightweight climbing attributes of cross-country
bikes and the strengths of downhill/freeride bikes.
Freeride Mountain Bikes are a step up again from Enduro
bikes. They tend to have the same 8 in (200 mm) of suspension
travel of downhill bikes, and are built from stronger,
heavier materials. They are designed to be an all-rounder,
able to cross distances (although not as quickly or efficiently
as an XC bike) and able to take on dangerous and technical
downhill trails (though not as quickly or effectively
as a specialist downhill bike). Many freeride bikes more
closely resemble downhill bikes and weigh as much, though
they are usually designed to be easier to pedal than a
downhill bike. Freeride bikes range in weight from the
low 30 to upper 50 pounds.
Downhill Mountain Bikes tend to be very heavy at over
40-50 pounds (18 to 23 kg) and have 8 in (200 mm) or more
suspension travel. They are very strong and (because of
typically large, high gears and long, soft travel) are
suitable only for riding down dedicated downhill trails
and race courses.
Trials Mountain Bikes that are set up very specifically
for the purpose of bicycle trials. They typically have
no suspension at all and only one gear, making them functionally
more like an oversized BMX bike than a conventional mountain
bike. Some trials bikes have no seat at all, or a vestigial
pad, 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 15 to 25 pounds. This
makes maneuvering the bike much easier.
Dirt Jumping, Urban and Street Mountain Bikes lie somewhere
in between a trials bike, a BMX bike and a freeride bike.
They are typically very strong bikes, with 3 to 5 in (75
to 125 mm) of front suspension, no rear suspension, and
often with just one gear.
Singlespeeds Singlespeeding is as much a life style as
it is a type of mountain bike. A singlespeed is just what
it sounds like - a mountain bike with one gear. Most singlespeed
riders choose to ride such bikes out of a love of simplicity,
elegance, and passion. The gearing ratio depends totally
on the terrain being ridden, the strength and skill of
the rider, and the size of the bike (a 29er often requires
a different gearing than a standard 26er). Often singlespeeds
are fully rigid, steel-framed bikes. One of the more popular
makers of singlespeeds is Surly. 4X racing is a new format,
and there are curently bikes emerging to fit into that
scene. these bikes are either full suspension with 3 to
4 inches of travel, or hardtails, and usually have quite
strong frames. They run a chainguide on front and gears
on the back.