Mountain Bikes

The history of the mountain bike includes contributions from cyclo-cross in Europe, the Roughstuff Fellowship in the UK. The name mountain bike first appeared in print in 1966 as "mountain bicycle". The mountain bike was a modified heavy cruiser bicycle used for freewheeling down mountain trails.

The sport became popular in the 1970's in Marin county. The 2007 documentary film, Klunkerz: A Film About Mountain Bikes, looks at this period of off-road cycling in detail. However, it was not until the late 1970s and early 1980s that road bicycle companies started to manufacture mountain bicycles using high-tech lightweight materials. Throughout the 1990s and 2000s, mountain biking moved from a little-known sport to a mainstream activity.

Cross Country mountain bikes usually 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.

Therefore, XC bikes are often less durable than other types of mountain bikes when used outside of their intended purpose. On full-suspension XC bikes, both front and rear, is typically provided by pneumatic (air) shocks or smaller coil/oil shocks and forks. Some full-suspension XC bikes may weigh as little as 21 pounds (9.5 kg), although they still are not as popular as hardtail XC bikes.

Many XC bikes have only front suspension and are normally referred to as hardtails. This is the most used type in XC competitions. A few 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 or general riding is the most popular form of mountain biking, focused on climbing and quick turning abilities rather than on the aggressive descent capabilities of freeride or single-purpose downhill mountain bikes.

XC bikes reflect this in their lighter weights and steeper geometries. However, due to their lighter frames and suspension, most XC bikes are poor choices for heavy-impact activities such as jumps and high-speed traverse of large obstacles such as rocks and deep washouts.

Freeride mountain bikes are like downhill bikes, but with less emphasis on weight and more on strength. Freeride bikes tend to have ample suspension and typically have at least 6 inches (150 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 manoeuvre 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 manoeuvrability over and around small objects. Freeride bikes typically range in weight from 30 to 45 pounds (14 to 20 kg).

Freeride trails are built using natural terrain features to create stunts such as drop-offs, also known as "hucks", narrow ladder bridges called "North Shores", 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, however, quite common for free riders to frequent lift accessed riding terrain, offered at ski resorts during the off season, or simply walk their bikes uphill, rather than riding them.

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 chain guide on front and gears on the back. They have slack head angles; short chain stays and low bottom brackets to aid in cornering and acceleration.

Until the late 1990s, mountain bicycles often had road bicycle style frames and geometry. In the 2000s, mountain bikes often use frames designed for off-road use, which strengthened to withstand jumps and impacts, and which use a geometry that allows for much more spirited riding over obstacles like logs, rocks, and ramps. In the 2000s, mountain bikes often have either 21, 24, or 27 speeds, with 3 gears in the front and 7, 8, or 9 gears at the rear wheel.

Thirty-speed mountain bikes have previously been unworkable, as the mud-shedding capabilities of a ten-speed cassette, and the intricacies of a ten-speed rear derailleur have never been suitable. However, many pro-level mountain bikers have taken to using a narrower 10-speed road chain with a 9-speed setup to reduce the weight of their bike.

In early 2009, component group SRAM announced their release of their XX group set, which uses a two-speed front derailleur, and a ten-speed rear derailleur and cassette, like that of a road bike. Mud-shedding capabilities of their ten-speed XX cassette are made suitable for MTB use by extensive CNC machining of the cassette. Due to the time and cost involved in such a product, they are only aimed at top-end XC-racers.

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. Forks are now available with 8 inches (200 mm) of travel or more (see above under "Design.") Bikes with front suspension and rigid, non-suspended rear wheels, or hardtails became popular nearly overnight. While the hardtail design has the benefits of lower cost, less maintenance, and better pedalling efficiency, it is slowly losing popularity due to improvements in full suspension designs.

Many new mountain bikes integrate a "full suspension" design known as Dual Suspension or "full-susser", meaning that both the front and rear tire are fitted with a shock absorber in some form as the wheel attaches to the bike to provide a smoother ride as the front and rear wheels can now travel up and down to absorb the force of obstacles striking the tyres. Dual suspension bikes are considerably more expensive, but this price increase brings an enormous performance upgrade as dual suspension bikes are much faster on downhill and technical/rough sections, than other forms of the mountain bike. This is because when the wheel strikes an obstacle its tendency is to bounce up.

Due to some forward energy being lost in the upward movement some speed is lost. Dual Suspension bikes solve this problem by absorbing this upward force and transmit it into the shocks of the front and rear wheels, drastically decreasing the translation of forward momentum into useless upward movement. Many bikes have dual suspension including downhill, freeride and mountain, although some bikes are built only to have front suspension e.g., dirt jump, some mountain. This makes them lighter and easier to control while in motion.

The advantages of dual suspension are increased comfort on rough terrain, and improved handling over obstacles. Disadvantages of rear suspension are increased weight, increased price, and with some designs, decreased pedalling efficiency. At first, early rear suspension designs were overly heavy, and susceptible either to pedalling-induced bobbing or lockout at certain points of the suspension arc or travel. One of the most popular rear suspension designs to solve these issues has been the 'Horst Link' which first appeared with the AMP series of bikes and was later adopted by Specialized and many other mountain bike manufacturers.

The disadvantage of disc brakes is their increased cost and often greater weight. Hydraulic disc brakes, which work by moving brake fluid through a hose or line to squeeze the pads together, require much more technical maintenance but enjoy far more stopping power and much longer service intervals than their mechanical counterparts. 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, however offering around the same amount of braking force as a V-brake, meaning that advantages of such a system over are limited to the general advantages of disc brakes over V-brakes, barring, of course, power - these include better performance in muddy and wet conditions, and ease of removing wheels.

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 a 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.

Disc brakes are a good choice for any type of riding, especially on wet and muddy terrain. In just about every form of MTB racing, V-brakes have become obsolete, replaced by hydraulic disc brakes - disc-brakes are a must for Downhill, as V-brakes are unable to provide the necessary stopping power. In pro-level XC racing, V-brakes have also become obsolete due to great weight reductions in hydraulic disc brakes (some sets today can weigh as little as 300 grams) and increasingly technical courses.

Most mountain bikes use 26-inch (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 622 millimetres (Template: Convert/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.[2] 24-inch wheels are used for dirt jumping bikes and sometimes on freeride bikes, rear wheel only, as this makes the bike more manoeuvrable. 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 tyres 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.

Although heavier wheelsets are favoured in the freeride and downhill disciplines, advances in wheel technology continually shave weight off strong wheels. This is highly advantageous as rolling weight greatly affects handling and control, which are very important to the technical nature of freeride and downhill riding. The widest wheel widths are sometimes used by ice bikers who use their mountain bikes for wintertime riding in snowy conditions.

Manufacturers produce a wide variety of tread patterns to suit different needs. Among these styles are slick street tyres, street tyres with a centre ridge and outer tread, fully knobby, front-specific, rear-specific, and snow studded. Some tyres 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 tyres tend to be lighter and have less rolling resistance.

Sticky Rubber tyres are now available for use on freeride and downhill bikes. While these tyres wear down more quickly, they provide greater traction in all conditions, especially during cornering. tyres and rims are available in either tubed or tubeless designs, with tubeless tyres recently (2004) gaining favour for their pinch flat resistance. Tubeless tyres can also be run at lower air pressures to improve traction and increasing rolling resistance.