The 1st downhill time-trial race took place in Fairfax, California on October 22, 1976 on a fireroad now referred to as Repack Road, due to the need to repack the single rear hub brake after a descent. The bikes used were based on beach cruisers that had a single rear brake that worked by pedalling backwards. A mechanism came into operation causing a conical metal (bronze?) brake shoe to be wound on a thread into a conical metal hub. To prevent a metal to metal brake from snatching it was always filled with grease. Heavy use of the brake during the descent would cause the brake to over heat, melting the grease till it drained from the hub and required repacking. Ten riders descended 1300 feet of Repack in about 5 minutes. The first bikes used for descending were known as "klunkers" or "paperboy bikes": coaster brake cruisers using balloon tires first imported to America by Ignatz Schwinn.By 1979, two organizers and competitors of the Repack downhill, Charlie Kelly and Gary Fisher founded the company which named the sport, MountainBikes. As mountain biking grew enormously during the 80s, downhill riders continued to use either rigid or limited suspension travel (under 2 inches) bicycles, and purpose made downhill bikes were not made until the 90s. Some of these innovations included dual crown suspension forks and disc brakes , as well as very elaborate frame suspension designs.

Dirt Jumping evolved alongside bmx racing from its birth. Dirt Jumping is similar to BMX or Mountain bike racing in that the rider jumps off of mounds of dirt . It differs in that the jumps are usually much larger and designed to lift the rider higher into the air. Additionally, the goal is not to complete the course with the fastest time, but rather to perform the best tricks with the best style. Trails are most often hand built, with attention to detail. A mountain bike built for dirt jumping tends to have a smaller frame than what is used for other disciplines. Running singlespeed is very common, as is using only a rear brake. In modern times, using single or dual disc brakes has replaced the use of only one rear V-brake. In general, a mountain bike dedicated to dirt jumping will have 24" or 26" wheels, a gear ratio of approximately 60 gear inches (~36:15 on a 24" rear wheel or ~36:16 on a 26" rear wheel) and rigid or 80-100mm travel forks. An 'all-round' bike used for dirt jumping will more likely have 26" wheels, a 30-36 teeth chainring with a wide-ratio cassette and a short- to mid-travel fork. Mountain bike dirt jumpers are usually split on the basis of wheel size because the wheel size dictates the shape of the takeoff to an extent. Dirt Jump bikes are made by a variety of companies. A couple of the most commonly purchased bikes for the general purpose of dirt jumping include the Kona DirtJump series (Kona Shred, Scrap, Stuff, Cowan), the P. series by Specialized (P.1, P.2, P.3, etc), Norco Dirt And Street Series and Transition's Trail-or-Park bike. Giant also has a StreetTrailPark line that is suitable for jumping, the STP 0-3 series.

Mountain bike trials , also known as observed trials is a discipline of mountain biking in which the rider attempts to pass through an obstacle course without setting foot to ground. Derived from motorcycle trials , it originated in Spain and is said to have been invented by the father of Ot Pi , a world champion motorcycle trials rider. Pi's father had wanted his son to learn motorcycle trials by practising on an ordinary push bike.

Trials riding is an extreme test of bicycle handling skills, over all kinds of obstacles, both natural and man-made. It now has a strong — though small — following worldwide, though it is still primarily a European sport. Skills taken from trials riding can be used practically on any bicycle for balance, for example controlled braking and track standing , or balancing on the bike without putting a foot down. Competition trial bikes are characterised by powerful brakes, wide handlebars, lightweight parts, single-speed low gearing, low tyre pressures with a thick rear tire, distinctive frame geometry, and typically a lack of seat.