Mountain bike

From Free net encyclopedia

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A mountain bike, mountain bicycle or ATB (All Terrain Bicycle) is a bicycle designed for mountain biking, 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 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 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").

1 Designs
2 History
3 Modern Bikes
4 Tire sizes
5 Wipe-Outs
6 Latest trends
7 Future bikes
8 See also
9 External links

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Designs

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

Hardtail: frame with no rear suspension, often has a front suspension fork
Fully Rigid: sub-type of hardtail, with a rigid fork
Dual or Full suspension: front suspension fork and rear suspension integrated into the frame
Soft Tail: frame with small amount of rear suspension, less than full suspension 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 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 (in suspension travel) from Enduro bikes. They tend to have 7-8 in (170-200 mm) of travel, and are built from stronger, heavier materials. They are designed to be able to cross distances (although not as quickly or efficiently as an XC bike, and with great effort on the part of the rider) 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. All frame angles are a bit steeper than a DH bike in order to make manoevering on narrow obstacles possible. 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. However heavy they may seem, they are built as light as possible for racing. They are very strong (but not as strong as a freeride bike) and (because of typically large, high gears and long, soft travel) are suitable only for riding down dedicated downhill trails and race courses. The suspension is set up to sag at least 3 inches, making for incredible traction through bumpy corners. The head angle can be as slack as 64 degrees.
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. However, the use of a short-travel suspension fork is becoming popular with some Trials riders. 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. Some people consider trials bike not to be truly mountain bikes.
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 6 in (75 to 150 mm) of front suspension, no rear suspension, and one to nine gears. Tires on these bikes are usually fast-rolling, slick or semi-slicks.
Single-speed 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" (or just because they are masochists). 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, a bike with 29" wheels, often requires a different gearing than a bike with standard 26" wheels). 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. They have slack head angles, short chainstays and low bottom brackets for good cornering and acceleration.

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History

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 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. [1]

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.

In the 1990s, disc brakes wern't very popular with riders due to the difficulty to find replacement parts. This difficulty was caused by each bike manufacturer having a different system of mounting the brake to the hub/frame. In the 1990s the brake manufacturing company Hayes brought all of the major bike manufacturers to find a universal mounting system. The international system was born. The disc (rotor) bolts to the hub with six bolts, and the piston/caliper/brake pad assembly bolts to the fork/frame using two bolts.

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Modern Bikes

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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, 27 or 30 speeds, with 3 gears in the front and 8, 9 or 10 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 weight, increased amount of suspension travel, and improved feel. Many lock out the rear suspension while the rider is pedaling hard or climbing, in order to improve pedaling efficiency. Most suspension frames and forks have about 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, and almost all mountain bicycle riders use a suspension fork. Well-known suspension fork manufacturers include Manitou, Marzocchi, Fox, Rock Shox, Pace and RST.

"Full suspension" mountain bike technology has made great advances since first appearing in the early 1990s. Early full suspension frames were heavy and tended to bounce up and down while a rider pedaled. This movement was called pedal bob, kickback, or monkey motion and took power out of a rider's pedal stoke — especially during climbs up steep hills. Input from hard braking efforts (known as brake jack) also negatively affected early full suspension designs. When a rider hit the brakes, these early designs lost some of their ability to absorb bumps — and of course this happened 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 1991, while working for AMP Research, (owned and run by another motorcycle racer named Horst Leitner) Karl Nicolai designed a bike that utilized the four bar linkage design and accepted a normal cantilever brake. This bike was initially marketed under the AMP brand and a version came to the mass market as the Specialized FSR. It became the standard by which all other full suspension designs were judged for the next decade. Specialized bought several of Leitner's patents in May 1998 and other manufacturers (ironically now including Nicolai himself) must now pay licence fees to Specialized for the use of the 'Horst Link' suspension design.

The amount of travel on full suspension bikes has steadily increased with 100 now acceptable for XC race and up to 150mm on trail or enduro bikes. For freeride and downhill even more suspension is the norm. Technological advances have enabled these machines to be of similar weight and cost of high end hardtails of the mid 1990s.

Several different full suspension designs are now well established in the marketplace.

The simplest — the Single Pivot — which Cannondale, Santa Cruz, Mountain Cycle, and even cheap department store bikes still use.

The Four Bar (and its variant the Faux bar) use several linkage points to activate the shock. A 'true' Four Bar will have pivots behind the bottom bracket, one in front of the rear wheel drop out, and at the top of the Seatstays. A Faux Bar will be similar but will have a pivot above the drop out instead of in front of the drop out. The importance of this one pivot is heavily debated with supporters on both sides of the debate. Four Bar designs include Norco "VPS" bikes, almost all Specialized bikes, Ellsworth, KHS, Turner (although their new 06 Flux has lost the Horst link), and Ventana. The VPP (or Virtual Pivot Point) is a linkage designed bike that is built to activate the suspension differently depending on what inputs the suspension has received. The VPP design can vary and designs from Intense, Santa Cruz, Iron Horse and Haro all exist.

The Soft Tail, which relies on the flexing of the rear triangle and a rear shock placed in line with the seat stays. The Soft Tail is one of the simplest designs introduced. Soft tail designs are a variation of the original Amp Research Mac-Strut design (technically a 3 bar suspension design). The design is currently falling out of favor because its main benefits — simplicity and firm pedaling — can both be achieved with other designs with more, and possibly, better suspension. It does not do well over small ripples or any kind of large bumps.

Almost all of the full suspension designs have been able to benefit from advances in new suspension technology. A stable platform shock is the latest design to hit the market and reduces unwanted bob. There are several different designs that have come to market with Fox, Manitou (whose SPV Evolve and Intrinsic forks are truly awesome), Rock Shox, and several smaller companies now in the fray.

Specialized, long an innovator in the bicycle industry, introduced the Specialized Epic, featuring the Brain(TM) shock. This makes the 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 VPP (Virtual Pivot Point) system used by Santa Cruz and Intense, also claims to have reduced the problem of pedal bob. Soon after the VPP was introduced, the creation of the Progressive Suspension 5th Element rear shock (based on Currnut's platform damper) near the beginning of the Millennium allowed riders to adjust almost any frame, regardless of design, to be pedaled without the pedal bob that plagued earlier designs. Other companies have followed Progressive's lead (mainly Manitou with its SPV system based on the 5th Element and Fox's ProPedal which uses a shim stack rather than an air pressurized valve) and a revolution in suspension design is underway. However, these 'intelligent' shocks always have to compromise between their resistance to bob and performance with small bumps.

Many think the tried and trusted technology of the four bar linkage with a comparatively simple shock still offers the best performance. Ironically, as shock manufacturers compete to have the latest 'pedal platform' technology four bar riders are pushed to the most expensive dampers on which it is possible to switch off the pedal platform! With the rise of more complicated shocks and a larger market share of full suspension bikes mountain bike suspension tuners have now arrived. It is now possible to have shocks tuned to individual rider's desires.

All high level mountain bikes now feature disc brakes. Disc brakes offer improved stopping power and modulation over rim brakes. Their increased height keeps them out of puddles, and rotors don't get bent as easily as rims do. Although disc brakes are more expensive than rim brakes they need less maintenance: pads last longer and can be changed very easily. Hydraulic brakes move brake fluid through a hose or line to squeeze the pads together, while cheaper mechanical brakes pull one pad toward the other with standard brake cable, similar to V-brakes. Disc brakes are produced by companies as varied as Avid, Hope, Shimano, Hayes and Magura.

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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 700 mm diameter wheel, which has a 622 mm (24.48 inch) bead seat diameter.

24 inch wheels are used for dirt jumping bikes and sometimes on freeride bikes, rear wheel only, as this makes the bike more manoeverable. 29 inch wheels are for Cross Country only.

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 tyres recently (2004) gaining favor for their pinch flat resistance. Tubeless tires can also be run at lower air pressures which some claim to improve traction while increasing rolling resistance. Popular tire manufacturers include Tioga, Kenda, Maxxis, Michelin, Panaracer and Nokian.

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Wipe-Outs

Part of the thrill of this sport, besides the beauty of being in the country, is the risk of a spectacular wipe-out. This can be due to equipment failure or mis-judgement on behalf of the rider, either way adrenaline flows. Many companies (Fox, RaceFace, 661 etc...) now produce protective gear "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 that market full body armour suits or jackets that allow the rider to remove some of the padding and/or plastic plates that protect the riders arms. Most upper body protectors also include a spine protector that is comprised of plastic plates joined together, with foam padding underneath. Full face helmets, often resembling motorcross 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.

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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.

Another important trend is the emergence of bike parks with a lift to the top. The obvious example is Whistler Mountain Bike Park, which opens during the summer at the popular Canadian ski resort Whistler Blackcomb. There are 40 or more trails, rated from very easy (blue) to very scary (double black diamond). The great thing about the park is that anyone can rent a top-quality bike (like Kona Stabs and Norco A-lines) for $100 and ride the lift to the top for $30. With no uphill pedaling to suffer through and the addition of adrenalin, mountain biking becomes fun for anyone.

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Future bikes

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Frame mounted gearboxes (generally hub gears adapted to fit) are starting to make an appearance in ultra high end mountain bikes. With the gearing system protected from the elements and from impacts and the weight of the bike held low and central these offer significant advantages over conventional gear systems, particularly for extreme use. These internally geared bicycles are often also referred to as three-speed bicycles.

Nicolai is currently one of the few manufacturers of internal gearbox bikes but other companies such as GT and Alutech have bikes near production. Nicolai use a 'standard' mounting for the gearbox called the G-Boxx, which has also appeared on prototypes from Evil Bikes and Alutech.

The German company of Rohloff also manufacture and supply a range of internal gearboxes (called the 'SpeedHub') to several bicycle manufacturers and initially also supplied Nicolai. It has since been standardized into the " G-Boxx" This system uses a seperate hub above the crankshaft and needs a second set of chains. This gives revolutionary smooth shifting when compared to any external derailleur currently made. The system is also maintenance free and incredibly tough. The main disadvantages are weight, price, and lack of spread of gearing. That is, a 14 speed rear hub gear does not support as wide a range as a derailleur system, so the rider needs to opt for a gear system biased towards low or high gears, primarily by choosing an appropriately sized front chainring. The increased weight of the rear wheel can raise some complaints; the new frame-mounted designs eliminate this problem by moving the weight into the centre of the bicycle. Note that this does not imply that hub gears are heavy: they apparently weigh the same as a classic derailleur setup.

Several companies are working on derailleur based frame mounted transmissions, but the benefits of these are subject to much dispute. Mountain Bike Action magazine reported in October 2004 that Hayes would manufacture and sell a transmission based on the PeteSpeed design. This appears to be targeted at downhill and freeride bikes, where it has the advantage that there is no rear derailleur that can be damaged by contact with rocks and other obstacles. However, the weight and restricted range of gearing compared with a traditional triple chainring and rear derailleur setup would seem to make it less suitable for cross-country riding.

Also available are rear hubs with a self contained CVT (Constantly Variable Transmission) within the rear hub of the bicycle. The external appearance is that of a single-speed bicycle, with one chain ring, one sprocket and a chain tensioner. Their primary disadvantage is weight, but their placement on the bicycle ensures that they will not be damaged by trail obstacles while riding. If this drivetrain design is improved upon in the future, it opens up the possibilities of bikes with motocross style concentric chain rings and suspension pivot points, thereby improving the durability of the bike.

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