Mountain bike

From Academic Kids

A rider during a Cross Country race
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A rider during a Cross Country race
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A mountain bike in the forest

A mountain bike, mountain bicycle or ATB (All Terrain Bicycle) is a bicycle designed for mountain biking and other 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, knobby tires for extra traction. In recent years front and/or rear suspension is becoming more popular. 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 tend to have 26" wheels (around 2002, some models introduced 29" wheels). Most newer Mountain bikes have either 24 or 27 speeds.

In French a mountain bike is called a VTT (vlo tout-terrain: "all-terrain bicycle").

Contents

Organizations

The International Mountain Bicycling Association (IMBA (http://www.imba.com/)) is a global organization that creates, enhances, and preserves mountain bike trails. The goal of the IMBA is to help maintain sustainable mountain bike trails that work well with the environment. The IMBA also travels around the globe and teaches many smaller mountain bike organization such as MORC (Minnesota Off Road Cyclists (http://www.morcmtb.org/)) and ERTA (Earthriders Trails Association (http://www.earthriders.org/)) how to maintain their own regions trails. Good trail maintenance is essential to the reputation and survival of mountain biking.

Union Cycliste Internationale is responsible for organizing mountain bike races globally. NORBA NORBA (http://www.usacycling.org/mtb/) (National Off-Road Bicycle Association) is responsible for organizing Mountain Bike races in North America. SORBA (http://www.sorba.org/) (Southern Off-Road Bicycle Association) is responsible for races in southeast North America. Cross-Country mountain bike racing is sport in the Summer Olympic Games.

Designs

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Freeriding on a Hardtail freeride bicycle

Mountain bikes can be classified into three categories based on suspension:

  • Rigid - no suspension
  • Hardtail - front supension 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 80-100mm) 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, up to around 30 pounds.
  • Enduro ( or "All-Mountain") Bikes are generally heavier than XC bikes (between 30 and 35 pounds), and have more suspension travel, between 100 and 150mm 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+" 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 (over 40-50 pounds) and have 8" 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 3-5" of front suspension, no rear suspension, and often with just one gear.

History

An entry-level mountain bike
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An entry-level mountain bike

Mountain biking started to evolve in the late 1960s and early 1970s. At the time, there was no such thing as a mountain bike. The earliest ancestors of modern mountain bikes were based around frames from road cruisers such as those made by Schwinn. Riders used balloon tired beach cruisers and modified them with gears and motocross style handlebars. They would bomb (ride fast) down mountain fireroads causing the hub bearings to burn the grease inside, requiring the riders to repack the bearings. These were called "repack races" and triggered the first innovations in mountain bike technology as well as the initial interest of the public. The sport originated in California [1] (http://www.mtnbikehalloffame.com/history.cfm?page=3).

It wasn't until the late 1970s and early 1980s that road bicycle companies started to manufacture mountain bicycles using high-tech lightweight materials. Gary Fisher is normally credited with introducing the first purpose-built mountain bike in 1979. The designs were basically road bicycle frames with a wider frame and fork to allow for a wider tire. The handlebars were also different in that they were a straight, transverse-mounted handlebar, rather than the dropped, curved handlebars that are typically installed on road racing bicycles. Also, some of the parts on early production mountain bicycles were taken from the BMX bicycle. The first mass-produced mountain bikes were produced by Specialized and were configured with 18 gears.

Modern Bikes

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A full suspension Mountain Bike

Until recently, mountain bicycles had road bicycle style frames and geometry. Mountain biking has become more mainstream with riding styles becoming more aggressive. Newer frames are better-designed, lighter, and stronger, with a geometry that allows for much more spirited riding over obstacles like logs, rocks, wooden bridges, and man-made ramps. Also, many riders are now jumping on mountain bicycles and taking on a more BMX style of riding. Newer mountain bikes have either 24 or 27 speeds, with 3 gears in the front and 8 or 9 gears at the rear wheel.

Many newer mountain bikes have a full suspension design. In the past, mountain bikes had a rigid frame and a rigid fork. In the early 1990s, mountain bikes started to have front suspension forks. This made riding on rough terrain easier on a rider's arms. The first suspension forks had about 1½ to 2 inches (38 to 50 mm) of suspension travel. Soon after, some frame designers came out with a full suspension frame which gave riders a smoother ride throughout the ride.

Newer suspension frame and fork designs have reduced the weight, amount of suspension travel, and feel. Many lock out the rear suspension while the rider is pedaling hard or climbing. Most suspension frames and forks have at least 4 inches (100 mm) of suspension travel. More aggressive suspension frames and forks made for downhill racing and freeriding have as much as 8 or 9 inches (200 or 230 mm) of suspension travel.

Many riders still prefer to ride a hardtail frame (bicycle with front but without rear suspension), and almost all mountain bicycle riders use a suspension fork. Well-known suspension fork manufacturers are, for example, Manitou, Marzocchi, Fox, Rock Shox, and RST.

Full suspension mountain bike technology has made great advances over the last few decades. Early full suspension frames were heavy and bounced up and down while a rider pedaled. This movement was called pedal bob, kickback, or monkey motion. This extra movement took power out of a rider's pedal stoke, especially during climbs up steep hills. Input from hard braking efforts called brake jack also negatively affected early full suspension designs. When a rider hit the brakes, these early designs lost the ability to absorb bumps. This effect rendered the bike virtually a hardtail in situations where the rear suspension was needed most.

The problems of pedal bob and brake jack began to be solved in the early 1990s. One of the first successful full suspension bikes was designed by Mert Lawwill, a former motorcycle champion. His bike, the Gary Fisher RS-1, was released in 1990. It adapted the A-arm suspension design from sports car racing, and was arguably the first four bar linkage in mountain biking. This design solved the twin problems of unwanted braking and pedaling input to the rear wheel, but the design wasn't flawless. Lawwill's design was hindered because it couldn't use traditional cantilever brakes and had to use disc brakes. A lightweight, powerful disc brake wasn't developed until the mid 1990s, and the disc brake used on the RS-1 was its downfall. In 1993, another motorcycle racer named Horst Leitner designed a bike that utilized the four bar linkage design and accepted a normal cantilever brake. This bike was the Specialized FSR. This bike became the standard by which all other full suspension designs were judged for the next decade.

A new trend in mountain bikes is the popularity of dual suspension bikes with 4 or more inches of travel. Technological advances have enabled these machines to be of similar weight and cost of high end hardtails of the mid 1990s. Specialized, long an innovator in the bicycle industry, introduced the Specialized Epic, featuring the Brain(TM) shock. This makes the 5.5-lb frame a hardtail until a bump comes from below. This turns the bike into a fully-active full-suspension bike until the lack of additional bumps resets the frame to rigid mode. The Brain shock, produced by Fox Racing Shocks, has an inertial valve that makes this possible. It was this technology that enabled the Specialized Epic to become the very first full-suspension bike to ever win the World Cup.

The Santa Cruz VPP (Virtual Pivot Point) also claims to have reduced the problem of pedal bob. Soon after the VPP was introduced, the creation of the Manitou SPV Swinger rear shock near the beginning of the Millennium allowed riders to adjust almost any frame, regardless of design, to be pedaled without the dreaded pedal bob that plagued earlier designs. Other companies have followed Manitou's lead and a revolution in suspension design is underway. It must be noted that this new shock only solves the problem of pedal bob, but not that of brake jacking. The future will tell if the tried and true technology of the four bar linkage will be supplanted by designs inspired by the new shock revolution in full suspension mountain bikes.

Tire sizes

Most mountain bikes use 26 in (559 mm) wheels, though some models offer 24 or 29 in (520 or 622 mm) wheels. Inch-sizes for bicycle wheels are not precise measurements - a 29 inch wheel is actually a 700c wheel, which is 622 mm, or 24.48 inches, in diameter. Wheels come in a variety of widths, ranging from standard rims suitable for use with tires in the 26 in x 1.90 in to 2.10 in (559 x 48 to 53 mm) size, to 2.35 and 3.00 in (60 and 76 mm) widths popular with freeride and downhill bicycles. Manufacturers produce a wide variety of tread patterns to suit different needs. Among the styles are: slick street tires, street tires with a center ridge and outer tread, fully knobby, front-specific, rear-specific, and snow studded. Tires and rims are available in either tubed or tubeless designs, with tubeless tires recently (2004) gaining favor among downhill riders for their flat resistance.

Latest trends

Some of the latest trends in mountain bikes include long-travel mountain bikes such as the Santa Cruz V10, and the Specialized Demo 9. On the other end of the travel spectrum, rigid singlespeed mountain bikes have appeared on the market, including the Bianchi SASS, the Kona Unit, and to an extent, the KHS Solo-One. These bikes are a celebration of the simplicity of the original mountain bikes of the 1970s at a time in which new innovations in suspension design and implementation are at the forefront of bicycle technology. Many experienced riders own rigid singlespeed bikes, finding the lack of complexity and the light weight to be attractive qualities.

See also

es:Bicicleta de montaa fr:Vlo tout terrain it:Mountain bike nl:Mountainbike ja:マウンテンバイク pl:Rower grski ru:Горный велосипед sv:Mountainbike

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