CYCLING - BMX
BMX riders in action.
Cycling - BMX
One of the most thrilling and action-packed of all the sports at the Olympic Games, BMX racing guarantees plenty of drama.
In such an explosive sport, where a race can be over in around 30 to 40 seconds, making a good start and achieving the 'holeshot' is crucial.
This term refers to the rider who holds the lead at the first corner and that, along with avoiding the crashes that have become such a feature of the sport, is vital in a successful race strategy.
With so many twists and turns, overtaking can be difficult, and so the rider who leads early on tends to have a significant advantage and goes on to win more often than not.
Those riders who attempt an overtaking manoeuvre run the risk of crashing out - although in such a high-drama sport that is over so quickly, taking a chance can sometimes pay dividends.
Given the speeds involved and the fact that eight riders race wheel-to-wheel around a tight course of around 350 metres, the likelihood of seeing a dramatic coming-together is high.
When the sport made its Olympic debut at Beijing 2008, for example, the story of both the men's and women's finals centred around two crashes.
Latvia's Maris Strombergs took gold in the men's race, but only after three riders crashed out on the second corner.
In the women's final, Great Britain's Shanaze Reade tried to pass eventual gold medal winner Anne-Caroline Chausson on the last corner but clipped the French rider's back wheel and was sent tumbling out of the race.
Such drama and excitement makes BMX racing one of the most popular sports on the Olympic Games schedule with spectators.
Bicycle motocross (BMX) was inspired by the motorised version of the sport, motocross, which became popular in the USA in the 1960s and 1970s.
The profile of the sport grew over the next two decades and in 1993 BMX was fully integrated into the International Cycling Union (UCI) programme, before first appearing in the Olympic Games 15 years later.
The structure of a BMX competition involves an individual time trial seeding round, followed by a series of heats in which riders aim to be one of the 16 semi-finalists.
The two semi-finals see eight riders battle for points across three races to try to qualify for the medal showdown.