How to get your heart racing

In 1991, while wondering whether it was wise to turn down a PhD to write novels instead, I was zapping through TV channels and found myself transfixed by a bunch of boys on bikes. The sight was compelling and slightly ridiculous. Why would men want to scale mountains in blistering heat by bicycle for a job, when most normal people would rather ski down them? I had no idea what they were doing, why they'd even want to be up that mountain. I was hypnotised by all the Lycra, the brawny bronzed limbs, the tanned faces razored by pain and contorted with suffering.

I became a bike bore overnight, soon to denounce any friend who didn't marvel at men whose hearts can pump at over 190 beats per minute yet be brought down to a resting pace at which most people ought to be dead.

I decided against the PhD in favour of writing novels, turning deaf ears to anyone who dared suggest I find a proper job. In January 1996, life became a fairy tale. My books became the subject of a bidding war between five publishers. Sally, my first novel, focused on sex and sin in Highgate, Chloe, my second, on love and debauchery in the UK at large, and Polly, my third on lust and iniquity in England and America. I enthused that Cat, my fourth, would centre on the Tour de France. At that point, the deal almost fell through. Cycling? In France? Men with shaved legs and silly helmets...? Suddenly, expressions were ominously blank - as was the cheque for the advance. I had my work cut out, popularising a sport that carries little weight in Britain while persuading publishers that the best way to do this was by writing a feisty romp based around it.

Though I'd have preferred to have discoursed on the entire 1989 tour, on 8litre lung capacities, the gradient of Mont Ventoux and the mighty, five-times Tour winner Miguel Indurain, I gave them what they wanted to hear. I reasoned this was a sport with teams called BigMat, Chicky World and OilMe; with riders called Eros and Angel. And, of course, thighs with an 80cm diameter. "Lashings of Lycra!" I declared. "Big bulges and bigger egos! A squadron of beautifully muscled, glistening thighs!" Smiles spread, contracts were signed and I had the go-ahead to indulge my passion for cycle sport by making it the setting for a novel.

Finally, it was time to infiltrate the professional cycling fraternity. I proposed to write a story about the world's most mesmeric sport - the world's most taxing, spectacular sporting event, the Tour de France - a mainstream novel to widen the appeal of a sport misunderstood in Britain.

Initially, I came up against the same resistance as I had at the publishers. A feisty romp about the Tour de France? Written by a female who prefers riding horses to bikes? Bribery seemed my only option and soon enough I had a healthy trade in fictitious seduction scenes in certain chapters....

A year later, I am a citizen of Planet Tour. I joined the 180 riders, the world's elite, at Le Puy du Fou theme park in the Vendee region three weeks ago. They set off to race 3,690km across France by bike. I've been following them by press car. I'm exhausted. The Tour de France has an entourage of 3,500 people: the Garde Republicaine motorbike squad; 1,500 vehicles including trucks 15m long; a fleet of helicopters; 13,000 gendarmes and 15 million roadside spectators. Days of the week have become Stages. Home is a succession of one-star establishments, none reached before 10pm. Sleep is a precious commodity, directly proportionate to the thickness (or paper-thinness) of the walls. There's a new language to learn. To talk lucidly about Ludo Dierckxsens of Lampre Daikin or Javier Pascual Llorente of Vitalicio Seguros in a conversational way still requires a certain confidence.

The Tour de France. La Grande Boucle. Hell on Two Wheels. Twenty teams participate yet only one man can win. In the peloton - the generic name for the multinational river of bright energy, the colour splash of Lycra, the 180 pairs of pumping thighs - there is only a mere handful of serious contenders for overall victory. The Maillot Jaune. The Yellow Jersey. The Golden Fleece. It is worn by the rider who completes the race in the fastest time - who can cope with the sprint mayhem of the flat terrain, the intense power required for the three individual time trials against the clock - and the mountains. Up the Alps and over the Pyrenees. In heat and in sleet. There's the Green Jersey too, for daily consistency; also the Polka Dot Jersey, for King of the Mountains. However, the majority of the peloton have no goal, no desire for a jersey; they are content to be domestiques. They are selfless workhorses, riding under a seemingly derogatory term, which defines the caste system in road-racing. To be a domestique is not an apprenticeship, it's a role. If your leader requires water, give him yours. Shield him from the wind. Be his lead-out man in sprints, peeling off at the last moment so he can reap the glory. In the mountains, offer him your slipstream and enable him to conserve 10 per cent more energy. If his bike should fail him and speed is of the essence, give him yours - it is probably set up to his measurements anyway.

This is a sport of triumph over adversity, man against mountain. The rider set to wear the Maillot Jaune on the podium in Paris is 27-year- old Lance Armstrong of the US Postal Team - returning to the Tour de France having fought testicular cancer. This year, the Tour de France is something of the proverbial phoenix, having risen from the debacle of last year's race when drug scandals and sabotage saw it rechristened the Tour de Farce. This is the sport with the most dope controls and longest list of banned substances. If a rider drinks over five cups of coffee, he risks being in breach of the caffeine limit. Armstrong has just had to defend his integrity when it was revealed the cream he uses for saddle sores contained traces of outlawed corticoids.

In the press corps of 1,000, I am one of only six women. It's been fairly trying. Fighting for your ground, not just for quotes, at the media scrum at the finish line. Facing banks of bottoms at urinals in the toilets. There is only one female team doctor and one female soigneur (the saintly support staff who care for the riders' every needs - from massage to hauling their suitcases from hotel to hotel) on the race.

On the Continent, professional cyclists are national legends. Ask any European for their heroes and a cyclist's name will trip off their tongue. In France especially, the Tour defines the country's calendar and culture. It is the Greatest Sporting Show on Earth. It breaks bodies and spirits as well as records. And it's beautiful to watch - an adventure, a soap opera, a piece of theatre unfolding against a stunning backdrop. More than anything it is a journey which touches deeply all those who experience it. For those who stand for hours by the road for a 20-second flash of Lycra or religiously watch it on TV. For those, like me, who trawl the kilometers by press car and the brave men who experience the lie of the land, the traumas of every millimeter by bicycle because that's their job. Vive le Tour!

Freya North's novel 'Cat' will be published by Heinemann in November.