The accused: Is Lance Armstrong’s life built on a lie?

Lance Armstrong, sporting hero or drug-taking cheat? As the allegations fly, Simon Usborne says that there is an empire built on empathy at stake, not just a few yellow jerseys

Lance Armstrong during the 2003 Tour de France (Reuters)

A video posted to Lance Armstrong's website in 2009 shows the cyclist training for the Tour de France on the fearsome Col de la Colombière, one of the great climbs. Drenched in sweat and panting as he takes on the steepest section before the summit, Armstrong is seen overtaking a small boy riding with his father.

"What's your name?" Armstrong asks, slowing slightly. "Liam," replies the boy, who is eight years old. Liam wears the yellow and black of Livestrong, the foundation Armstrong set up after surviving testicular cancer. He also sports a yellow wristband, one of 80 million Armstrong has sold for a dollar each, and rides a bike like his hero's, except it's so small the tubes that make up its frame are almost as thick as Liam's little legs. "You know I could barely catch you," Armstrong tells the beaming boy.

I'd forgotten about the clip until last week when I watched an investigation into alleged doping by a man who is a role model to millions. Rumours of drug-taking have surrounded Armstrong like a cloud of mosquitoes for much of his career but he has always strongly denied them, often by means of lawsuits. Now the biggest threat to his reputation - and legacy - has come with stinging accusations by a former teammate. Tyler Hamilton told the CBS News show, 60 Minutes, that, among other things, he and Armstrong had taken the blood-boosting drug EPO together. Armstrong denied the allegations, his spokesman accusing Hamilton of inventing the story to get a book deal. Last week, his lawyers demanded an on-air apology. 60 Minutes refused, insisting its story was "truthful, accurate and fair".

I've always been fascinated by the Armstrong myth. He survived a cancer that ought to have killed him and, thanks to talent, grit and a Hollywood life story, joined the ranks of the few who become bigger than their sport. His total domination of the Tour de France, the world's greatest race, earned him many fans as well as detractors, some of whom accuse him of leeching the romance out of a beautiful sport. A French philosopher called him "Robocop on wheels, someone no fan can relate to or identify with", but for many there was something irresistible about his story.

Buying into the myth also means rejecting the rumours. I've always believed they were sticks jammed by incredible witnesses into the spokes of a one-man brand that has energised a sport and raised almost half a billion dollars. But those allegations, more details of which later, have shaken my belief. That's when I remembered Liam. At a time when celebrities argue the case for being famous yet fallible, Armstrong is the paradigm example of a role model. Tiger Woods was guilty of cheating, if of a different sort, but arguably his greatest achievement outside his sport was to inspire people to like golf and buy things. Armstrong has built an empire of empathy on a foundation of greatness, inspiring millions to ride, "live strong", and raise money in his name. But can a man's achievements be great enough to stand in the face of claims that they rest on lies? If it all came tumbling down, how would Liam feel?

Lance Armstrong has a big heart. If you're an average man, your heart isn't much more than half the size of Armstrong's. When resting, it beats 32 times a minute (yours beats twice as quickly) climbing to 200 beats per minute when he's really pushing it. It means he can get oxygen to his muscles more efficiently than almost anyone else. His thighs, meanwhile, are disproportionately long, making excellent levers, and he carries less fat than a whippet. He is built to ride and, after modest beginnings, developed a brain that was wired to win.

Born in 1971 in a Dallas suburb to a single mother and an absent father he later described as "a DNA donor", Armstrong would astonish cycling coaches as a teenager with his natural ability, yet frustrate them with a lack of discipline and respect. But talent was enough and, aged 23, he became world champion and the youngest rider to win a stage of the Tour de France.

Two years later, he felt a lump in one of his testicles. Surgeons removed it but by then cancer had reached his lungs and brain. More surgery followed as well as chemotherapy so powerful it permanently damaged his kidneys and burned the inside of his skin. Doctors gave Armstrong a "minority chance" of seeing out the year. He survived, of course, and soon reached for his bike, whereupon something changed. Before his illness, he relied on talent rather than proper training or teamwork. His gift was rare but was never enough to make him great. But, as the cyclist's former coach, Chris Carmichael, told the New Yorker magazine in 2002: "When [Lance] came back, he just went into a different zone. He works as if he is possessed."

What followed led Armstrong to call cancer the best thing that ever happened to him. He won the Tour de France a record seven times in a row between 1999 and 2005 before announcing his (temporary, it turned out) retirement. Riding the Tour, which covers more than 2,000 miles in three weeks, has been compared to running 20 marathons back to back. Armstrong conquered the world's most gruelling test of endurance year after year with fried kidneys and one testicle. A feat like that will get you attention.

In 2009, I travelled to Avellino near Naples to watch a stage of the Giro d'Italia, or tour of Italy. It wasn't long before Armstrong's return to the Tour de France. Before the start, in a sunbaked car park, fans and media were free to walk between the team buses and catch glimpses of riders. Armstrong'steam bus was besieged. For a giant, he is surprisingly slight, the crowd the only clue as to the stature of a man who revolutionised cycling. Armstrongdrew unseen levels of media interest and sponsorship to a sport that had rarely been seen as glamourous and, as the millions poured in, cycling came to revolve around its biggest star. Ned Boulting joined the Tour as a reporter for ITV in 2003. "We all relied on the Armstrong brand to sell products, earn riders their salaries, or journalists their place on the Tour because most broadcasters were only interested in Lance," says Boulting, who shares his experiences in his book, How I Won the Yellow Jumper. "He dragged an enormous economic slipstream that was hard to escape."

It would not be in the sport's interest were the Armstrong myth to crumble. Nor would it be in the interest of Livestrong, which raises more than $50m a year and helps hundreds of thousands of sufferers around the world. Armstrong's first, best-selling book, It's Not About the Bike: My Journey Back to Life, published in 2000, has helped countless more. I met Nick Dodds last summer at the Etape du Tour, the amateur stage of the Tour de France, in which thousands of riders take on a gruelling mountain stage days before the professionals. In 2003, Dodds, who works for Sky, had been given a copy ofArmstrong's book while he was being treated for testicular cancer. "I devoured it in half a day," he says. "It taught me that I could focus on the negative and not solve the problem or, in the midst of this dark cloud, find something good."

Geoff Thomas wasn't remotely interested in cycling during a career in football that included nine caps for England. He read Armstrong's book days after being diagnosed with leukaemia in 2003. "It inspired me to look beyond the illness and made me want to pay a little back," he says. Thomas, 46, was moved by Armstrong to set up the Geoff Thomas Foundation, which has raised more than a million pounds. In 2005, he rode the entire route of the Tour de France, winning the BBC Sports Personality Helen Rollason Award for his efforts. At the ceremony, Armstrong sent his congratulations via video link from his home in Austin, Texas. "He probably didn't know me from Adam but it was a nice touch," Thomas says.

Armstrong is big on nice touches, as Liam discovered in France. Both exchanges were filmed (the French encounter from the rider's team car) andArmstrong looked good. His harshest critics accuse him of using charity to help burnish his image. But he launched his foundation in 1997, before he had much to lose - before the Tour victories, the millions and the celebrity girlfriends (Armstrong, 39, has five children under 11 by his ex-wife, Kristin, and current partner, Anna. In between those relationships he found time to date Sheryl Crow and Kate Hudson). What the cameras don't see is the speeches, the handshakes, the lobbying or the hospital visits. Few would doubt his intent or ability to inspire.

Which brings us back to those mosquitoes The day after the Hamilton interview, Armstrong tweeted: "20+ year career. 500 drug controls worldwide, in and out of competition. Never a failed test. I rest my case." But Hamilton had gone further, alleging that Armstrong had indeed tested positive during the 2001 Tour of Switzerland, but that the UCI had suppressed the results. Armstrong's lawyers strongly deny the allegation. The rider's lawyer told the Independent: "A record of all positive tests recorded during that race demonstrates that Mr Armstrong did not test positive. The UCI also denies the allegation, saying Armstrong had "never been notified of a positive test result by any anti-doping laboratory", and that it "reserves the right to take any measures it deems necessary against Mr Hamilton or any other person".

Hamilton also claimed George Hincapie, whom Armstrong has described as being "like a brother", had given evidence to an ongoing federal investigation into doping allegations against Armstrong. Hamilton said Hincapie had also admitted taking EPO with Armstrong. Hincapie denied talking to 60 Minutes and has refused to comment on the investigation. Armstrong's lawyers later released a statement accusing 60 Minutes of also attacking Hincapie'sreputation: "We are confident that the statements are inaccurate... and... unreliable."

The federal investigation is being lead by Jeff Novitzky, the relentless agent who blew open Balco, the company that supplied drugs to athletes including the US sprinter, Marion Jones. When asked to comment on the federal investigation, Armstrong's lawyer, Mark Fabiani, told the Independent: "Lance has said that... his focus is [now] on his family, the Livestrong Foundation, his business ventures and other causes... He's hired people to handle the enquiry, and he's moving forward on all the other fronts."

Whether or not Novitzky finds anything in his pursuit of Armstrong - and we may not find out for months - the range of opinions on sporting blogs include many who find his repeated denials ridiculous.

And yet many others believe him. When I emailed Dodds asking to speak to him about Armstrong, he replied: "I do hope you aren't going to write anything nasty about Lance! It would make a change if someone actually chose to defend him." Dodds compares Armstrong to Alberto Contador. The Spanish rider tested positive for a banned substance he claims to have been present in beef he ate on the way to winning last year's Tour de France. His fate was due to be decided today but the case was delayed until August, freeing up Contador to defend his title next month. "If that were Lance, the press would be having an absolute field day," Dodds says.

Armstrong stirs fierce loyalty in those he's touched - and they are legion. They say he is unfairly targeted by spiteful journalists. They say his accusers are discredited by their own admissions of drug taking or, in some cases, a desire to sell books, one of the accusations levelled at Hamilton. Leave the guy alone, they say. But Armstrong deserves the greatest scrutiny because of what he stands for. And if, as he insists, he's innocent, the myth lives on. As American rider Greg LeMond put it in 2001: "If Lance is clean, it is the greatest comeback in the history of sport. If he isn't, it would be the greatest fraud."

When you ask believers how they would feel if Lance were to be found guilty of doping, there is always a pause. Dodds, 40, admits it would be a "huge slap in the face" but adds: "Lance's message about cancer would be no less valid. If he doped and indirectly it helped him win and that indirectly helped save a life, it's a price worth paying." For some, Armstrong is bigger than the crimes he's accused of. "If Lance were a cheat, it wouldn't mean anything to me," Geoff Thomas says. "When I read the book, it was what I needed at the time and it got me to where I am today. What I have has gone beyond him - he was just the trigger."

Armstrong was never a hero to me but as someone who admired him and bought the story, I'd be disappointed if it turned out it to be too good to be true. It would be a sporting fall from grace to dwarf all others and I struggle to believe some of those he inspired would not feel a little cheated. In the meantime,Armstrong, who announced his final retirement from professional cycling in February, will turn 40 in September. He's returning to next month's Tour not to ride but to supports his old teammates. Liam will be there, too. He's still in France, living and riding in Provence with his father, William Flannagan, who brought the family from its home in California. When I ask William how he would feel if Armstrong were found guilty, he also pauses... "When Lance biked up to us in the Alps it was like he was the modern Achilles or Nike," he says. "But he's not a god, he's human." Flannagan takes the phone away from his ear to ask Liam, who is now 10: "Would you still see Lance as a hero if he was caught doping?" Again, the pause... "Yeah," Liam can then be heard saying, before adding, "But not as much."