Graphic: long and winding road to victory

The Tour de France turns its back on its recent troubled past today when the 2008 race begins in Brittany, with an opening 197.5km stage from Brest to Plumelec and the promise of a new beginning.

Among the favourites to take the first yellow jersey of this year's race will be Mark Cavendish, the sprinter from the Isle of Man. Irrepressible, on and off the bike, Cavendish spent yesterday lunchtime entertaining photographers with a series of provocative poses outside the Tour press centre.

It may be tempting fate, but Cavendish, whose medical profile is regularly monitored by both his sponsor and, as an Olympic athlete, by Team GB, may be the closest thing to “a guy we can believe in”, to paraphrase the term used to describe Tyson Gay, the American sprinter seen as a leader in the clean-up of athletics. The scepticism remains here, however, at the notion of a totally clean Tour peloton.

Nonetheless, Cavendish's youthful cheek encapsulates the hopes for the renewal of the tainted Tour, an event so mired in scandal and suspicion over the past decade that its prestige has diminished enormously. In the ten years since the Festina Affair first laid bare the scale of corruption, a fierce battle has been fought to save the dignity of the old race. It is not over.

This year's Tour has a new heart-shaped logo, reading “Le Tour Toujours”, and the favourite to rekindle lost affection for a sporting event that was first staged 105 years ago is the steadily improving Cadel Evans, from Australia, who has transformed himself from a tactically naive former mountain biker to an accomplished time-triallist and mountain climber.

Until this season, Evans had not shown the aggression and dominance required to secure the yellow jersey, but his performances this spring, particularly in the Paris-Nice race in March, have indicated his growing maturity as a stage-race rider.

Beyond Evans, come a cluster of nearly men, the most promising of whom, Alejandro Valverde, of Spain, won last month's week-long stage race, the Dauphiné-Libéré, in the French Alps. But the Spaniard's Tour record is uneven - he is as likely to crash out of the race, as he is to win it.

If form dictates that Evans and Valverde are the outstanding favourites, the most volatile contender is Riccardo Ricco, who at 24 has yet to win a leading European stage race. The Italian's attacking climbing style has brought comparisons to the late Marco Pantani, but he seems more likely to concentrate on stage wins than overall victory.

This year's route reflects the mood of innovative optimism. There is no prologue time-trial and the first mountain stage comes as early as stage six, with the summit finish at Super-Besse in the Massif Central. Three more mountain-top finishes come later on a course that Christian Prudhomme, the Tour director, describes as “about tactical intelligence and opportunism, not just brute force”.

If the Tour route has undergone a makeover, then so have the images of some of the sport's leading teams, who have scrambled to shore up the faltering confidence of sponsors. In-house anti-doping programmes are in vogue, with teams spending almost €500,000 (about £400,000) a season on internal testing. The T-Mobile team from Germany have changed into the American-based Team Columbia, while CSC, who were forced to remove Iván Basso, their team leader, from the 2006 Tour because of his connections to the Operation Puerto doping scandal, have become Team CSC-Saxo Bank, with a stringent testing programme run by Rasmus Damsgaard, the renowned Danish anti-doping campaigner.

In the most striking turnaround, Bjarne Riis, the CSC general manager, who was shamed by his admission of using drugs on his way to victory in the 1996 Tour, has become a campaigner for clean sport. “Things have changed,” Riis said. “I know how our team, CSC, is working. We're clean.”

The inclusion of the Garmin-Chipotle team, led by David Millar, whose anti-doping programme has been approved by the World Anti-Doping Agency (Wada), is also indicative of the hunger for change. Garmin-Chipotle have struggled for success this season, but ASO, the organiser of the Tour, has been won over by their ethical stance.

The best efforts of others, however, have not been as well received. Alberto Contador, the champion, will miss the race because of the ban on Astana, his team, whom Contador joined last autumn. The team had been taken over by Johan Bruyneel, the former mentor to Lance Armstrong. He was charged with the task of cleaning up the team's act and his efforts included employing Damsgaard as the team's drugs tsar, but Bruyneel and Contador underestimated the level of anger that ASO had with Astana's old guard, which had presided over a series of doping scandals in 2006 and 2007.

Even so, there are many within cycling who feel that Contador has been unfairly denied the chance to defend his title. “The decision is completely unjust,” Pat McQuaid, the president of the International Cycling Union, said. “ASO say that Astana damaged the Tour last year, but so did four other teams. Riis admitted that he took drugs when he won the Tour, yet his team is welcomed.”

Contador's absence will soon be forgotten, possibly as soon as the first mountain stage on Thursday. In the end, however, all the semantics and feuding will be easily dismissed if, for the first time in a decade, the race reaches Paris untouched by scandal and unimpeded by the intrusion of the French gendarmerie.