A mountain bike or mountain bicycle (abbreviated MTB or ATB (All Terrain Bicycle)) is a bicycle designed for mountain biking, either on dirt trails or other unpaved environments. In contrast, road bicycles are not rugged enough for such terrain.
Mountain bikes have wide, knobby tires for extra traction and shock absorption. In recent years, front wheel suspension has become the norm and full front and rear suspension is becoming increasingly common. Some mountain bikes are also fitted with bar ends on the handlebars, but with the increase in popularity of riser handlebars (as opposed to a flat straight handlebar) fewer riders use bar end extensions. The bikes normally have 26 in (559 mm) wheels, but since 2002 some models have been available with 29 in (622 mm) wheels, which is the same diameter most commonly used for road bikes. (The name given to a rim diameter in inches is different from the rim's actual size.)
Designs
Mountain bikes can be classified into four categories based on suspension:
- Fully Rigid: A frame with a rigid fork and fixed rear, no suspension.
- Hardtail: A frame with no rear suspension. These bikes are most often used with front suspension.
- Soft Tail: A frame with small amount of rear suspension, but activated by flex of the frame instead of pivots.
- Dual or Full Suspension: A front suspension fork and rear suspension with a rear shock and linkage that makes the rear wheel move on pivots.
Discipline oriented designs
There are several different styles of mountain biking, usually defined by the terrain, and therefore bikes employed. All of the bikes in this category fall into one of the above four categories and bikes of each of the above style can be found almost any of the following categories.
- Cross Country (XC) mountain bikes typically have only a small amount of front and/or rear suspension (usually 65-110 mm) and are relatively light, which is achieved via the use of lightweight materials and construction in both frame and components. As a consequence, XC bikes are often less durable than other types of mountain bikes when used outside of their intended purpose.[citation needed] Suspension, both front and rear, is typically provided by pneumatic (air) shocks and forks, which saves weight. Some XC bike models have no suspension and use a rigid front fork, saving weight but relying more on rider skill to negotiate rough terrain. XC riding is the most popular form of mountain biking, focused on efficient climbing rather than aggressive descending. XC bikes reflect this in their lighter weights and steeper geometries than downhill bikes. However, most XC bikes are poor choices for stunts like jumps.
- Enduro/All-Mountain (AM) bikes are generally heavier than XC bikes, typically weighing between 30 and 35 pounds (14 to 16 kg). These bikes tend to feature greater suspension travel, frequently as much as 150 mm of front and rear travel, often adjustable on newer mid and high end bikes. They are designed to be able to ascend and descend mountains, integrating the climbing abilities of XC bikes with the suspension technology of freeride bikes.
- Freeride (FR) mountain bikes are similar to All-Mountain bikes, but with less emphasis on weight and more on suspension. Freeride bikes tend to have up ample suspension, with 7 (178 mm) or more inches of travel fairly commonplace. 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 30 to 45 pounds. Freeride trails usually use the natural terrain to create stunts such as dropoffs, narrow ladder bridges called "skinnies", as well as large ramps built to launch the rider into the air. 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. It is common for freeriders to frequent lift accessed riding terrain, offered at ski resorts during the off season, or simply walk their bikes uphill, rather than riding them.
- Downhill (DH) mountain bikes typically have 7 or more inches (178 mm) of suspension travel. They are built as strong as possible for reliability during racing and weigh around 40-45 lbs (21 kg). Due to their typically large or high gears and long, soft travel, Downhill bikes are suitable only for riding down dedicated downhill trails and race courses. The suspension is set to sag around 30% front and 50% rear of full travel, creating ample traction around bumpy corners. The head angle is often as slack as 64 degrees. Most riders who ride exclusively downhill do so in competitions or ride almost exclusively on lift accessed terrain, but tramming up to the top of runs is still by far the most popular as most trails do not have lift access. Pushing the bike to the top is also a commonly used method. 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.
- Trials mountain 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 15 to 25 pounds. This makes manoeuvring 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 0 to 4 inches of front suspension, and rarely any rear suspension (3 to 4 inches 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 "bash ring" replacing the largest ring on the crankset.
- Single-speed 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 "4-cross racing" (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 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 for good cornering and acceleration.
- North Shore mountain biking originated in the steep, wet, rocky, rooty terrain of Vancouver, Canada's north shore, thus it was coined "north shore" riding. Because of the almost, if not completely impassable terrain, riders began building bridges over muddy areas, rocks, stumps and deadfall. These bridges evolved into complex, often extremely challenging, man-made stunts. Because stunts are often narrow and may require the rider to move very slowly regardless of width, north shore riding requires immense balance and bike handling skills. 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.
History
Riding bicycles off-road goes back to the beginning of cycling itself. Road racing cyclist had long used cyclo-cross as a means of keeping fit during the winter, eventually becoming a sport in its own right with the first world championship in 1950. The French Velo Cross Club Parisien (VCCP) comprised about twenty-one young bicyclists from the outskirts of Paris, who between 1951 and 1956 developed a sport that was remarkably akin to present-day mountain biking. [1] The Roughstuff Fellowship was established in 1955 by off-road cyclists in the UK [2]
However the mountain bike has its origins in the modified heavy cruiser bicycles used for freewheeling down mountain trials in California, U.S.A. in the mid-late 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 cruiser bicycles such as those made by Schwinn. The Schwinn Excelsior was the frame of choice due to its geometry. Riders used balloon tired cruisers and later modified them with gears and motocross style handlebars. They were called Klunkers. The term would also be used as a verb since mountain biking was not yet in use. They would race down mountain fireroads causing the hub brake 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 the U.S. state of California, on Marin county's famous mountain, Mount Tamalpais. [3]
It was not until the late 1970s and early 1980s that road bicycle companies started to manufacture mountain bicycles using high-tech lightweight materials. Joe Breeze is normally credited with introducing the first purpose-built mountain bike in 1978. Tom Ritchey then went on to make frames for a company called MountainBikes which was a partnership between Gary Fisher, Charlie Kelley and Tom Ritchey. Tom Ritchey with his skills in frame building also built the original bikes. The company's 3 partners ran into rough times and finally fell apart at the 1983 trade show[citation needed]. The designs were basically road bicycle frames (with heavier tubing and different geometry) 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 in 1983 and were copies of Tom Ritchey's frames, but they were not fillet-brazed, and were made in Japan. They were configured with 15 gears.
Modern Bikes
Until recently, mountain bicycles had road bicycle style frames and geometry. Mountain biking has since 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.
Newer mountain bikes have either 21, 24, or 27 speeds, with 3 gears in the front and 7, 8, or 9 gears at the rear wheel. 30 speed mountain bikes are currently unworkable, as a slimmer 10-speed chain is not strong enough.
Geometry
The critical angles in bicycle geometry are the head angle (the angle of the head tube), and the seat tube angle (the angle of the seat tube). These angles are measured from the horizontal, and drastically effect the rider position and performance characteristics of the bicycle. In general, steeper angles (closer to 90 degrees from the horizontal) are more efficient for pedaling up hills and make for sharper handling. Slacker angles (leaning farther from the vertical) are preferred for high speeds and downhill stability.
Suspension
Many newer mountain bikes have a "full suspension" design but this isn't always the best way to go hardtails are lighter and you don't lose pedal efficiency, meaning the both front suspension forks and some form of rear suspension as opposed to front suspension only ("hard tail").
In the past, mountain bikes had a rigid frame and fork. In the early 1990s, the first mountain bikes with suspension forks were introduced. This made riding on rough terrain easier and less physically stressful. 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 still smoother ride.
The classic hardtail design is still favored by 65% of mt bikers (source mbuk) because it doesn't lose pedaling efficiency and its a hell of a lot cheaper and less prone to damage/service!
Disc brakes
Most mountain bikes now feature disc brakes. These offer improved stopping power over rim brakes under adverse conditions, because they are located at the center of the wheel (on the wheel hub) and therefore remain drier and cleaner than wheel rims, which are more readily soiled or damaged.
The disadvantage of disc brakes is their increased cost and often greater weight. Maintenance is also more difficult, particularly with hydraulic disc brakes, which work by moving brake fluid through a hose or line to squeeze the pads together. Mechanical disc brakes, which are simpler and somewhat less expensive, work in a similar fashion to rim brakes by pulling one pad towards the disc with a cable.
The braking power of a disc brake also depends on the size of the rotor. For example, an 8-inch rotor has more stopping power than an 6 inch rotor of the same design (about 33% more). This is because the brake caliper can apply more torque with the same amount of force because the larger disc provides a longer moment arm.
Wheel and tire design
Most mountain bikes use 26 in (559 mm) bicycle wheels, though some models offer 24 or 29 in (520 or 622 mm) wheels. Bicycle wheel sizes are not precise measurements, a 29 inch mountain bike wheel actually has a 622 mm (24.48 inch) bead seat diameter (the term, bead seat diameter (BSD), is used in the ETRTO tire and rim sizing system). 622 mm wheels are standard on road bikes and are commonly known as 700c. In some countries, mainly in Continental Europe, 700c (622 mm) wheels are commonly called 28 inch wheels.
24 inch wheels are used for dirt jumping bikes and sometimes on freeride bikes, rear wheel only, as this makes the bike more maneuverable. 29 inch wheels were once used for only Cross Country purposes, but are now becoming more commonplace in other disciplines of mountain biking.
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. Some tires can be specifically designed for use in certain weather (wet or dry) and terrain (hard, soft, muddy, etc) conditions. Other tire designs attempt to be all-around applicable. Within the same intended application, more expensive tires tend to be lighter and have less rolling resistance. Tires and rims are available in either tubed or tubeless designs, with tubeless tires recently (2004) gaining favor for their pinch flat resistance. Tubeless tires can also be run at lower air pressures to improve traction and increasing rolling resistance. Popular tire manufacturers include Wilderness Trail Bikes, Schwalbe, Maxxis, Nokian, Michelin, Continental, Tioga, Kenda, Hutchinson and Panaracer.
Protective equipment
Inherent in the sport of mountain biking is the risk of injury. Many companies now produce protective gear, often referred to as "armor," to protect against injury from crashes, mostly aimed at downhill, freeride and dirtjump riders. Armor ranges from simple knee and elbow pads to full body padding. Some companies market full body armor suits or jackets that allow the rider to remove some of the padding and/or plastic plates that protect the rider's arms. Most upper body protectors also include a spine protector that comprises plastic plates joined together, with foam padding underneath. Full face helmets, often resembling motocross helmets (but usually considerably lighter and with more ventilation) are required by some bike parks, although advanced riders often wear these helmets by choice, in order to better protect their heads. Backpack hydration systems such as Camelbaks are also considered to be armor by many riders for their valuable protective effects[citation needed].
Latest trends
Some of the latest trends in mountain bikes include the all mountain bike, the 29er and the singlespeed. The "all mountain bike" is characterized by 4-6 inches (100-150mm) of travel, the ability to descend and handle very rough conditions and still pedal efficiently for climbing. 29er bikes are those using 700c sized rims (as do most road bikes), but wider and suited for tires of two inches (50mm) width or more; the increased diameter wheel is able to roll over obstacles better and offers a greater tire contact patch. The single-speed is considered a return to simplicity with no drivetrain components or shifters, but thus requires a stronger rider.
Another interesting trend in mountain bikes is outfitting dirt jump or urban bikes with rigid forks. These bikes normally use 4-5" travel suspension forks. The resulting product is used for the same purposes as the original bike. A commonly cited reason for making the change to a rigid fork is the enhancement of the rider's ability to transmit force to the ground, which is important for performing tricks.
Rapid popularity increase has led to the development of mountain bike oriented resorts, similar to or in the same complex as a ski resort. There parks include chairlifts which are adapted to bikes, a number of trails of varying difficulty, and bicycle rental.
See also
- UCI Mountain Bike & Trials World Championships
- Mountain unicycling
- Mountain Quadracycle
- National Off-Road Bicycle Association (NORBA)
- List of bicycle manufacturers
External links
- Mountain Bike Hall of Fame
- How to choose a mountain bike
- Glossary of terms
- IMBA (International Mountain Biking Association)
- "A Brief History of the Mountain Bike" by Jobst Brandt
- Mountain Bike Reviews, by Samuel Mascarell
- Mountain Bike Roots - photos and race results from 1980s events
- The Wheel World
- Pinkbike
- Farkin (Yes this is a mountain bike site!
- Southern California Mountain Bike Rider Community
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