Cycling BMX Women's BMX Final - London 2012 Olympic Games

A look back at the London 2012 Olympic Games...

Mariana Pajon women's BMX Gold medal winner dominated her three semi-final runs in awe-inspiring fashion, led the eight-rider strong field after the first bend and never looked back. New Zealand's Sarah Walker took silver and Dutchwoman Laura Smulders claimed bronze while local hope Shanaze Reade settled for sixth. She finished just behind Caroline Buchanan of Australia, the BMX time trial world champion.

The first national mountain bike championships were held in 1983 in the USA. But the sport quickly grew in popularity in Europe and Australia. The first mountain bike World Championships, recognised by the International Cycling Union (UCI), were organised in 1990. Olympic recognition followed and mountain biking made its debut as an Olympic discipline at the Atlanta Games in 1996, with a cross-country event for men and women. The programme has remained unchanged ever since.

It was in 2008 in Beijing that BMX made its debut on the Olympic programme. BMX is one of the fastest and youngest cycling disciplines. Its principle is simple: eight riders compete on a track filled with jumps, tight bends and obstacles.

Brooke Crain honors injured U.S. teammate in Olympic BMX final

Photo shows Brooke Crain at the starting gate of the women's Olympic BMX final, she flashed a message written on her glove. Three letters: "A-M-V."

This was her personal tribute to Arielle Martin-Verhaaren, the 27-year-old rider who suffered serious injuries when her bike chain broke during her last training run for London on July 30.

Martin suffered "severely lacerated liver and collapsed lung in the resulting crash." as reported by Salt Lake Tribune, " Her injuries made it too dangerous for her to join the team in London, even as a spectator. After three surgeries, she's still hospitalized.

It would have been Martin's first Olympics; instead, it was Crain's, as the U.S. team's designated alternate. It could have been Martin racing in the final of the London Games' women's BMX competition in Olympic Park; instead, it was Crain.

Racing against the world's elite riders, Crain had the slowest time in the final, finishing in eighth place at 40.286 seconds. Mariana Pajon of Columbia won gold at 37.706, after rolling through the heats.

Crain, 19, discovered she was replacing Martin the night before the team was leaving for London. She would have flown over with the team anyway, lodging with them and soaking up the Olympic experience. But now she wasn't a tourist  she was a competitor for a medal.

During the seeding heats, Crain's Olympic dream appeared like it might end. On the last straightaway, her back wheel clipped a hill.

Her torso plowed into the ground, her body lifted up and then slammed to the ground a second time. She was helped up off the course, but eventually rode off slowly on her bike. U.S. team officials later said she was sore but anticipated she would race in Friday's semifinals.

The crash nearly taketh away, and then the crash giventh in BMX: In the second semifinal race, a huge collision of riders around the first turn left just three racing towards the finish line. One of them was Crain, who placed third in the race to bolster her chances to advance. One of the riders caught in the mayhem: Alise Post, a U.S. rider many expected to advance.

Despite the crash, Post was third overall entering the final race of the heat.

That's when disaster struck for the 21-year-old rider: With four hills to go before the finish, Post crashed her bike and needed to be helped from the track.

She finished eighth; Crain was third in the semifinals.