"A type of bicycle which breaks down more often than other types."
- The Pedaller's A-Z
Generally, a sport of competition and recreation revolving around the riding of bicycles off-road, i.e. on trails.
These are the three main forms of competition, i.e. The Big Three. Although you may find several others listed at Wikipedia, these are the only disciplines I have ever seen at a sanctioned event (not to say you wouldn't ever find the others at national/regional competitions). For instance, so called endurance events (i.e. 24 hour races) are souped up versions of XC competition.
Cross Country (XC)
These races take place on a varied terrain circuit. Which is to say, courses generally consist of a 5 to 8 mile loop which is repeated a number of times. Most races are somewhere between 20 and 40 miles. Please note that cross country mountain biking is the only discipline present in Olympic competition. When most people think of a mountain bike, they are thinking of a cross country mountain bike.
Pretty much a downhill time-trial. Downhill racing is not for the faint of heart. When was the last time you flew past trees less than a foot away at over 50 mph? The bikes used in downhill racing are completely different beasts than those used in cross country racing and are usually well over 30 lbs in weight.
Dual Slalom (DS)
My favorite discipline. A dual slalom course consists of two identical, man-made, downhill, BMX style tracks with berms and jumps. Most races are over in less than 30 seconds. The bikes used in DS competition are somewhat toned back downhill bikes, i.e. they are lighter and don't have as much travel up front in the shocks (although you could probably do fine with either style of bike). I personally ride my XC hardtail with the seat lowered all the way down when I am competing in a dual slalom race.
These are the two major groups of recreational riders. It is important to note that there is a fair degree of overlap between these two groups. Additionally, many racers may ride alternative disciplines recreationally.
Cross Country / Fitness
Consists of trail riding. If any of you noders out there have never gone mountain biking, or are looking for a great way to stay in shape, I recommend cross country trail riding. While many trails are extremely difficult technically (rocks, roots, cliffs...), there are also many easy cross country trails, which require almost no technical ability.
Free / Street Riding
Involves riding your bike off of high drop-offs and hoping that nothing breaks... again...
Roots of the Sport
The origin of the sport of mountain biking is a testy issue for some riders, as there are several opinions on the true roots of the sport. What follows is a brief rundown of some of the highlights of the sport's early history.
Buffalo Soldiers Bicycle Corps
In August 1896, the Buffalo Soldiers rode from Missoula, Montana to Yellowstone and back--a trip through over 800 miles of wilderness. The goal of the expedition was to test the bicycle for use in transporting gear over mountainous terrain.
Velo Cross Club Parisien (VCCP)
The French Velo Cross Club Parisien (VCCP) was comprised of about twenty young bicyclists from the outskirts of Paris who between 1951 and 1956 developed a sport that was remarkably akin to present-day mountain biking. Their Velo Cross sport had little to do with skinny-tire cyclo-cross racing of the day, and although they did not use mountain biking’s highly inspirational balloon tire, the spirit, purpose, and passion of mountain biking were there.
- MTB Hall of Fame
John Finley Scott
A mountain biker in a world without mountain bikes. He built his own bike known as a "Woodsie" in 1953 and rode the trails on his own. The "Woodsie" featured a Schwinn World Diamond frame, balloon tires, flat handle bars, derailleur gears, and cantilever brakes.
The Cupertino Riders
This is where the modern sport of mountain biking began, in the early 1970's with the creation of the Morrow Dirt Club of Cupertino, California (75 miles north of Marin). While others had "mountain-biked" per se, these guys created a sport that did not die off and survives continuously through to this day (the others mentioned in this roots section represent isolated occurences, not the birth of a sport). The Cupertino Riders modified there bikes by grafting thumbshift operated derailleurs and motorcycle-lever operated drum brakes. In 1974, the Morrow Dirt Club made an appearence at the Marin County cyclocross race. People noticed that they were different, that they rode different bikes, rode with a different attitude.
At the same time, on an old dirt road west of Fairfax (Marin County) guys would haul their klunkers (i.e. heavy and heavily modified bikes) up "to the top of the ridge for the downhill thrill." The road drops 1300 feet in less than 2.1 miles. It has been described as a "twisting, ...precipitous descent." This fire road was called Repack, Repack Road:
...the hub coaster brakes would get so hot that the grease would vaporize. After a run or two the hub had to be repacked with grease, hence the name of the road.
- MTB Hall of Fame
These guys invented nothing short of downhill mountain biking. And when boys of the Morrow Dirt Club paid a visit to Repack in the mid 1970's, their technology once again, left an impression. This time however, one of the Marin County locals took notes. His name was Gary Fisher.
I could go into the early politics of the sport. Disagreements between NORBA and USCF, and ownership bullsh*t, but that stuff is boring. Go read about it somwhere else. All I know is this, almost twenty years to the day after the first DH competition at Repack, XC mountain biking was included in the 1996 Olympic games in Atlanta.
I myself ride mountain bikes for the Mizzou Cyling Team. I love mountain biking. The only thing I don't love is when people haven't ridden the trails in awhile, and spiders have taken over. Now get off your lazy ass and go ride the trails... and get rid of all those spiders for me.