Mountain bike

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This article is about mountain bikes themselves. For the associated activity, see Mountain biking.
A full-suspension mountain bike

A mountain bike or mountain bicycle (abbreviated MTB or ATB, for all-terrain bicycle) is a bicycle created for off-road cycling.





A cross country mountain bike race.

The history of the mountain bike includes contributions from cyclo-cross in Europe and the Roughstuff Fellowship[1] in the UK. The name "mountain bike" first appeared in print in 1966 as "mountain bicycle"[citation needed]. The original mountain bikes were modified heavy cruiser bicycles used for freewheeling down mountain trails. The sport became popular in the 1970s in Northern California, USA with riders using older single speed balloon tire bicycles to ride down rugged hillsides.[2] Joe Breeze, a bicycle frame builder, used this idea and developed what is considered the first mountain bike.[3] 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, such as M4 aluminium. The first mass production mountain bike was the Specialized Stumpjumper, first produced in 1981.[4] Throughout the 1990s and 2000s, mountain biking moved from a little-known sport to a mainstream activity complete with an international racing circuit and a world championship.


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

  • Rigid: A frame with a rigid fork and fixed rear, no suspension.
  • Hard tail: A frame with a front suspension fork and no rear suspension.

Discipline-oriented designs[edit]

2008 GT Zaskar Pro Carbon Hardtail cross country mountain bike with carbon frame and disc brakes
Mountain bikes are built tough to withstand jumps and drops.

There are several different styles of mountain biking, usually defined by the terrain, and therefore bikes employed. Styles of mountain bike riding and mountain bikes have evolved rapidly in recent years leading to terms such as Freeride and "Trail bike" being used to categorise mountain bikes. Definitions for the most widely used terms are listed below.

Cross country (XC) mountain bikes are designed primarily around the discipline of cross country racing. Cross country racing with its emphasis on climbing as well as speed and endurance demands bikes that are both lightweight and efficient. In the 1980s and early 1990s XC mountain bikes typically consisted of a lightweight steel hardtail frame with rigid forks. Throughout the 1990s XC bikes evolved to incorporate lightweight aluminium frames and short travel (65 to 110 mm) front suspension forks. Recently full suspension designs have become more prevalent, and the use of advanced carbon fiber composites has allowed bike designers to produce full suspension designs under 10 kg. In recent years 29" wheels have become more popular too, the US men’s and women’s marathon cross-country races were won on 29ers in 2009 and 2010.[5] The geometry of Cross Country bikes favours climbing ability and fast responses over descending and stability and as a result typical head angles are 70–71°. Although intended for off-road use, Cross Country mountain bikes with their emphasis on lightweight construction are not designed for use on the most steep or severe terrain.

"Trail" Bikes are a development of XC bikes that are generally used by recreational mountain bikers either at purpose built "Trail centers" or on natural off-road trails. They usually have around 5" (120–140 mm) of travel, weigh 11 to 15 kilograms (24 to 33 lb), and have geometries slightly slacker than XC bikes, though not as slack as AM bikes. Examples include the Giant Trance, the Trek Fuel EX series, the Specialized Stumpjumper FSR, and others. With less of an emphasis on weight, Trail Bikes are typically built to handle rougher terrain than dedicated XC bikes while having slacker head angles (69-68°) which provides greater stability while descending.





Slopestyle (SS) combination of Dirt and Freeride

Trials 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 7 to 11 kilograms (15 to 24 lb). This makes maneuvering the bike much easier.

A simple dirt jump bike.


Single-speed (SS) 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 "Four-cross" (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 102 mm) 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 to aid in cornering and acceleration.






Modern designs[edit]

A 2002 rigid 21 speed Trek 800 Sport


Main article: Bicycle gearing

From the 1980s to the late 2000s, mountain bikes often had 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 dérailleur 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 in an effort to reduce the weight of their bike. In early 2009, component group SRAM announced their release of their XX groupset, which uses a two-speed front dérailleur, and a ten-speed rear dérailleur and cassette, similar to 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 were only aimed at top-end XC-racers. However, 10-speed has become the norm by 2011 and the market leader Shimano even offers its budget groupset "Alivio" in a 10-speed version.[7] In July 2012, SRAM announced a 1x11 drivetrain called XX1 that does not make use of a front dérailleur for lighter weight and simplicity.[8] In the 2014 Commonwealth Games at Glasgow all leading riders used 1x11 drivetrains.




A full suspension mountain bike
Main article: Bicycle suspension



Disc brakes[edit]

A front disc brake, mounted to the fork and hub
For further information see, see Bicycle brake#Disc brakes. For general information, see Disc brake.


Wheel and tire design[edit]

Most mountain bikes use 26-inch (559 mm) bicycle wheels, though some models offer 24 or 29 inch (520 or 622 mm) wheels, and 27.5 is currently appearing. Tire size can be chosen based on bicycling terrain and size of the person. A larger tire can cause geometric problems for a short rider. Bicycle wheel sizes are not precise measurements: a 29 inch mountain bike wheel actually has a 622 millimetres (24.5 in)) 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.[9] 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. A mountain bike with 29" wheels is often referred to as a 29er, and a bike with 27.5 inch wheels is called a 27.5 mountain bike or 650b bike. 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. Although heavier wheelsets are favored 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 icebikers who use their mountain bikes for winter-time riding in snowy conditions.


Tires also come with tubes, tubeless and tubeless-ready. Tires with tubes are the standard design and the easiest to use and maintain. Tubeless tires often have better performance because you can run them at a lower tire pressure which results in better traction and increasing rolling resistance. Tubeless-ready tires are tires that can use tubes or go tubeless. A liquid sealant is used without the tube to secure the seal to the rim.[10] Popular tire manufacturers include Wilderness Trail Bikes, Schwalbe, Maxxis, Nokian, Michelin, Continental, Tioga, Kenda, Hutchinson Specialized and Panaracer.

A tandem, full-suspension mountain bike



See also[edit]


  2. ^ Jobst Brandt ((1998/2005)). "A Brief History of the Mountain Bike". Retrieved 2013-12-26.  Check date values in: |date= (help)
  3. ^ Berto, Frank J. (2009). The Birth of Dirt: Origins of Mountain Biking. Van der Plas/Cycle Publishing. ISBN 978-1-892495-61-7. 
  5. ^
  6. ^ "Diablo Freeride Park". Archived from the original on 2008-05-03. Retrieved 2008-09-21. 
  7. ^
  8. ^
  9. ^ "Sheldon Brown: Tire Sizing Systems". Retrieved 2008-09-21. 
  10. ^ Campbell, Dan; Charlie Layton (May 2009). "Know Your Rubber". Mountain Bike: 51.