A trip to the cinema inspired Chris Hoy to take up cycling and set him on the path to Olympic history.

His mother Carol had taken her son, aged six, to see ET, the Steven Spielberg film about an extra-terrestrial. But Hoy seemed not to notice the lovable alien - he was transfixed by the BMX biking sequences.

Pestered by her son, Mrs Hoy bought him his first bicycle for £5 in a jumble sale in his home city of Edinburgh.

"Within two weeks he'd broken it doing wheelies," she said. "He was so disappointed I had to get him another one for £99 but I told him he had to pay half.

"He waited for his uncle and aunties to have a couple of glasses of wine and then he got the money off them."

Hoy began racing in earnest at seven, preparing meticulously for BMX races by setting up jumps in the garden and practising starts until it was dark. By 13, he had written in his diary of his determination to win Olympic gold, an ambition he has now achieved four times.

Hoy, 32, who shares his birthday with Sir SteveRedgrave, rowed for Scotland as a junior but deciding he was too small to make it on the water, switching full time to cycling at 17. He fitted his training around school work and then a degree in Applied Sports Science at Edinburgh University.

The head teacher at his school, George Watson's College, said Hoy had moved from his BMX obsession to track cycling after an Outward Bound trip organised by the school.

Hoy was made an MBE in 2005 after winning gold in Athens in the "kilo" sprint, an event that was axed for Beijing, forcing him to change to new disciplines with spectacular results. His dedication is legendary, training even on Christmas Day.

He was cheered to victory today by his mother, 60, his father David, 62, his sister Carrie, 35, and his girlfriend Sarra Kemp, 28, an Edinburgh lawyer.

Ms Kemp said: "He is such a gentle giant, but it is a very gladiatorial sport and he looks quite scary in his helmet."

Hoy's father said it was too soon to speak of his son rivalling Redgrave as Britain's greatest Olympian. But he added: "Chris is still young and will be there in London 2012, so let's wait and see."