(Reuters) - Focus on track cycling at the 2020 Tokyo Olmypics:
THE ABSOLUTE BASICS
* There will be six different track cycling disciplines at the Tokyo Games -- individual sprint, team sprint, keirin, team pursuit, omnium and madison.
* Track cycling bikes, unlike those used in road racing, do not have gears or brakes. They use a fixed gear meaning a rider cannot free wheel and has to pedal the whole time.
* Organisers strictly enforce regulations on equipment, but a huge amount of development goes into aerodynamics of frames and wheels and the skinsuits and helmets riders wear. Fractions of seconds can be the difference between gold and failure.
* Olympic track cycling takes place on a wooden oval of 250m. The track is banked to a dizzying 45 degrees.
HOW MANY MEDALS? There are 12 gold medals up for grabs in the six disciplines.
WHAT HAPPENED IN RIO?
Britain ruled the boards in Rio, as it had done in London in 2012, scooping six of the 10 titles on offer.
Only Italy's Elia Viviani prevented a full house for the British men as he edged out Mark Cavendish for gold in the omnium.
Sprinter Jason Kenny won three golds and his future wife Laura Trott won two, as she did in London, to become Britain's most successful female Olympian.
Germany's Kristina Vogel won the women's sprint gold but will not be defending her crown after a serious crash in training in 2018 left her paralysed.
WHAT CAN WE EXPECT IN TOKYO? That is the big question. With no world championships this year, as has been the case in previous Olympic years, gauging form will be harder than usual.
Britain will have a tough time emulating the gold-rush in Rio, especially in the blue-riband team pursuit events where the American women led by Chloe Dygert and the Danish men who blazed to the world title in 2020 in Berlin will be serious challengers for gold.
Britain's golden couple, the Kennys, will be confident of adding to their hauls with Jason requiring one more gold in what is almost certainly his farewell Olympics to move past Chris Hoy's British record six.
The two-rider multi-lap madison race, an event that can be a mystifying one to follow, will return to the Olympic programme for the first time since Beijing 2008 with the women's race making its Olympic debut.
WHEN IS IT HAPPENING? Aug. 2 to 8
WHERE IS IT HAPPENING? Izu Velodrome located in Izu City, Shizuoka Prefecture, 120km away from Tokyo.
HOW DID WE GET HERE? Track cycling has been part of the Olympics since the first modern Games in Athens in 1896, apart from Stockholm 1912.
WELL FANCY THAT
One of the most iconic track cycling events is the keirin -- in which sprinters are paced behind an electric motorcycle known as a derny for the first 5.5 laps of the eight-lap event, reaching 50kph. Once the derny pulls off, the race begins in earnest with a frantic battle to the line.
Keirin is massively popular in Japan where the word literally means "racing". Established in 1948, it attracts large crowds to outdoor velodromes where huge amounts of money are wagered and top riders, who begin at keirin schools dotted around Japan, can become millionaires.
It was added to the Olympic programme in 2000.
(Reporting by Martyn Herman, editing by Ed Osmond)