CYCLING - MOUNTAIN BIKE
A rider in action on the London 2012 Olympic mountain bike course.
Cycling - Mountain Bike
First developed as a past-time for thrill-seeking Americans, mountain biking has quickly become one of the most exciting sports on the Olympic schedule.
Riders display an almost care-free attitude as they race with little regard for their own safety at great speeds on varied and testing terrains.
Challenges come at every twist and turn of a cross-country course and include tricky rock hazards, steep climbs and technical descents - all of this while riders battle for position during a race.
The mass start and first-to-the-finish format means that mountain bikers have just one chance to get it right and this adds to the intrigue for spectators, who are able to get close to the action around a course that consists of both grassland and woodland areas.
The excitement begins right from the very start as riders set off together and aim to get to the front, often resulting in collisions and casualties.
Fifty competitors line up for the men's race at the Olympics and 30 for the women's race, with the first rider across the finish line declared the winner.
With races lasting between an hour-and-a-half and two hours, concentration is a key factor as the finest riders have their bike-handling skills and stamina tested to the limit.
Equally important are the high-performance mountain bikes that are used for competition. They need to be durable enough to cope with the difficult terrain, but still light enough to help with climbing and generating speed.
It was in the 1970s that tough new bikes capable of coping with the most challenging of terrains were developed and this gave cyclists much more freedom to leave the streets and go off-road.
The sport first started in California, USA, but its popularity soon spread to Europe and Australia. Seven years after the first national mountain bike championships were held in America, the first mountain bike world championships were held, in 1990.
Soon after, the sport's growing appeal across the world was recognised when it made its Olympic debut at Atlanta 1996, and it has been staged at the Games ever since.
France's Julien Absalon and Italy's Paola Pezzo have already claimed the accolade of winning back-to-back Olympic titles during their racing careers and are two of the most recognisable names in the sport.