It was in the late 1960s that mountain biking first began, when racing down fast on mountain trails, also known as 'Repack races', caught the imagination of biking enthusiasts. The race along with the trail it took place on was called 'Repack', because the twisting, torturous route downhill on Pine Mountain, California, forced the bikers to use the coaster brakes of their bikes to such an extent that the smoking hubs had to be repacked with grease after each run. These races also gave rise to the introduction of mountain trek bikes, or the kind of bicycles that were suitable for the rougher terrain involved in mountain biking. Although initially, it was merely a hobby, mountain biking would soon evolve into an athletic sport, with California being the first place where the sport began. It was in the latter part of the 1970s that bicycle manufacturers started producing specialized mountain bikes. Gary Christopher Fisher, a biking enthusiast who began taking part in track and road competitions at the early age of 12, is credited to have been the first to have created a specialized mountain bike. The mountain bikes of those days had wider forks and frames, along with wider tires. The handlebars of the trek bicycles used for mountain biking have a different design compared to regular bikes. Unlike the curved, dropped handlebars of road bikes, they are transverse-mounted and straight. The first mass produced trek bicycles meant for mountain biking were equipped with 18 gears. It was in the 1990s that the brake being mounted on the frame or hub was universally adopted, along with six bolts used for bolting the rotor or disc to the hub, as well as the system of using two bolts to attach the brake pad assembly or piston to the frame. Also, it was during this time that mountain bikes began to be equipped with front suspension forks, in order to make rough terrain bike riding easier on the arms of the riders. The mountain bikes that are available these days are much lighter and also offer many more options in the design of the suspension. Mountain bikes can be categorized into four classes according to their suspension: 1) Hardtail; 2) Fully-Rigid; 3) Full or Dual Suspension; 4) Soft Tail.

• The Hardtail Mountain Bike: The frame of the hardtail has no rear suspension, although it can come with a suspension fork in the front.
• The Fully-Rigid Mountain Bike: This is a sub-category of the hardtail, which has a fork that is built rigid.
• The Full or Dual Suspension Mountain Bike: As is suggested by its name, the frame of this bike is equipped with both front suspension in the fork as well as rear suspension.
• The Soft Tail Mountain Bike: These models are equipped with some rear suspension, with a frame having less suspension compared to a dual suspension bike.

It was in 2002 that mountain bikes began to come with wheels that measured 29 inches. The larger-sized wheels were created to enable the bike ride over obstacles much more easily compared to the usual 26-inch wheeled bikes. However, experts complain that the larger wheels make the bikes less maneuverable. These days, the technological advances that are being utilized to build the most user-friendly as well as the most stylish mountain bikes have given rise to a competitive business of creatively designed mountain bikes suitable for all sorts of terrain as well as budgets. Innovations in the designs are still continuing, and hence, it is expected that mountain biking enthusiasts will continue to be offered increasingly radical models in the future.