The forecast for the start of the 2008 Tour de France in Brest, Brittany on Saturday may be clear skies but the race will struggle to escape the low, dark cloud of drug scandals and scepticism.

Despite officials declaring that cycling has turned a corner and that this year's Tour will be as clean as it has been in years, the week preceeding the first stage has been tainted by the conviction of two high-profile stars, indicating the sport is still struggling to escape the stranglehold of cheating.

On Monday Floyd Landis, the American who won the 2006 Tour but was subsequently stripped of the title, had his appeal against a two-year ban for drug-taking dismissed by the Court of Arbitration for Sport.

On Tuesday, Denmark's Michael Rasmussen, who was sacked by Rabobank while leading last year's Tour because he had lied about his whereabouts during doping tests, was given a two-year ban by the Monaco Cycling Federation.

When Lance Armstrong retired in 2005 after seven successive Tour triumphs, it was hoped the event would enter a new, less controversial period.

Despite Armstrong never testing positive for a banned substance, doubts remained over the legitimacy of his supremacy following his comeback from cancer, and he was never a popular competitor in France, whose supporters did not like to see their race monopolised by one man.

But in the days leading up to the 2006 Tour, favourites Ivan Basso and Jan Ullrich were both forced to withdraw because of doping charges.

Then Landis, Armstrong's US Postal Service team-mate between 2002 and 2004, completed one of the greatest comebacks of all time to clinch the yellow jersey, but was later found to have excessive levels of testosterone in his system.

If that cast a shadow over the Tour, 2007's events brought it to its knees. Rasmussen and his team were thrown out of the race a day after pre-race favourite Alexander Vinokourov had also been disqualified. It was known as "Black Wednesday".

This time round there is renewed optimism though.

"There is a real change in mentality wiin the teams, the riders, to ensure that cycling recovers its credibility," said Tour director Christian Prudhomme.

David Millar, who was arrested by drugs police before the 2004 Tour but has since reinvented himself as an anti-doping campaigner, concurs. He now races for Slipstream, which has a strict anti-doping policy.

"It took last year's comical farce on the Tour, the foreboding that the sport would lose all its sponsors and money, to really wake it up," he said.

"I think teams like us, High Road and CSC are seeing the benefit of being ethically viable. It has an economic worth.

"The idiot teams never figured that out before. It was just win, win, win. Now there are two or three teams who are very ethical in their outlook and that is probably going to be a turning point in the sport."

However, it remains almost impossible to predict a winner.

Australian Cadel Evans, who was runner-up last year, is hotly tipped, as is brash Italian Riccardo Ricco, making his Tour debut. Frank Schleck is one of the favourites to win the polka-dot jersey for man of the mountains.

The course has been revamped - another sign the Tour is trying to start afresh.

For the first time since 1967, there will be no prologue to begin the battle. The pack will dive right into the race from the first kilometres of a hilly 195km first stage before fighting it out at the summit of the Cote de Cadoual.

Time bonuses have been abandoned so it could be a tighter, more dramatic race, especially in the mountains where decisive gaps between riders are often built early on. A brutal climb up the Alpe D'Huez on stage 17 has the makings for a classic.

There is one more mountain-top finish and fewer time-trials, which is good news for last year's winner Alberto Contador, but not so for Evans, who is a better time-trialist.

It is inconceivable the Tour will pass without any drug scandals but, after the events of the last two years, organisers and fans will simply be praying the winner wins clean.

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