The return of Lance Armstrong has caused mixed feelings in France [EPA]

Two new books on Lance Armstrong have also just been released in France.

The seven-time champion is back from retirement, four years after his last victory.

Teammate Alberto Contador, the 2007 winner and a top pre-race favourite, returns after Astana was not allowed to compete last year.

They are allies, but could become rivals too.

Gruelling race

The race starts with a challenging 10-mile prologue in Monaco, the tiny principality in southeast France.

The pack will then head out along the Mediterranean, through the Pyrenees, across central France, into the Alps and then up the fabled Mont Ventoux a day before the July 26 finish in Paris.

Riders will dip into Spain, Switzerland and Italy during the 2,140-mile trek and face 20 major mountain climbs during the three weeks.

Tour designers have spiced up the route and revived some rules from the good old days in hopes that fans will have something - anything - to get their minds off the drug use that has marred cycling's premier event in recent years.

Judges from UCI, the sport's governing body, will be back, a year after they were kept out because of a bitter spat with Tour organisers over doping that has now been patched up.

The UCI has rolled out its "biological passport'' anti-doping program, in which samples were taken from 840 professional riders to determine their body chemistry profiles.

Any suspicious fluctuation from those levels could lead to penalties, even if no specific substance turns up in tests.

Clamping down

France's anti-doping agency, the AFLD, says it is going to target suspicious riders, rather than focus on random tests used in previous years, and will test for an unspecified new drug.

The agency has also been authorised to freeze samples taken during the Tour.

This allows them to be tested in the future for drugs that haven't yet been identified as performance enhancers.

"We know there are some particular substances and methods, and we are going to try to detect them, sooner or later,'' said Pierre Bordry, head of the AFLD, which helped nab six cheats at last year's Tour.

"There are things that aren't found in blood, but I'm not going to give an example, because I've learned over the years the people who advise athletes on doping adopt their programs based on drug-testers' mindsets,'' Bordry said.

For Armstrong, who famously insisted he was the world's most-tested athlete during his glory years and has never tested positive, the welcome back to a still largely suspicious France may not be warm.

Just weeks before the Tour's start, two books - "La Grande Imposture'' (the Great Impostor) by anti-doping doctor Jean-Pierre Mondenard and "Le Sale Tour'' (The Dirty Tour) by Pierre Ballester and David Walsh - have come out in France to capitalise on the media frenzy over the American's comeback.

Both books lay out repeated suspicions about Armstrong over the years, though neither breaks significant new ground.

Controversy

Doping allegations have already depleted the field this year: Spain's Alejandro Valverde, the winner of the Dauphine Libere stage race and the top cyclist this year in the UCI rankings, has been forced to sit out because he is banned in Italy - which the Tour visits on July 21 - over doping allegations.

This Tour also offers some blasts from the past, including a team time trial in Stage 4 - the first since 2005.

Injecting a taste of yesteryear from when riders didn't enjoy high-tech communication, Tour organisers have banned the use of earpiece radios in the 10th and 13th stages - a controversial move that will alter strategies by stripping riders of their coaches' advice during the stage.

Armstrong's long-time mentor and coach, Astana team manager Johan Bruyneel, hates the idea.

"On the radio ban in 2 stages of the TdF?'' Bruyneel wrote on Thursday on his Twitter page.

"I absolutely disagree. What's the benefit of returning to the prehistory?''

But Bruyneel should be comforted by the team time trial, because his Astana squad has four of the world's best riders: Armstrong, Contador, American Levi Leipheimer, and Germany's Andreas Kloeden.

Alberto Contador is Armstrong's greatest rival [AFP]

Other innovations include an uphill finish at the moonscape-like Mont Ventoux in the next-to-last stage - an effort to dangle sporting suspense all the way up to the traditional cruise on Paris' Champs-Elysees for the finish.

Mont Ventoux's inclusion almost seems tailor-made for Armstrong, who has called it the toughest Tour climb "bar none'' - and one he has never won at cycling's showpiece event.

With Valverde out, the smart money will be on Contador. He sat out last year because Astana was barred from racing because of a doping scandal in 2007.

Other pre-race favourites include fellow Spaniard and 2008 Tour winner Carlos Sastre; Cadel Evans of Australia, runner-up last year and in 2007; and Denis Menchov, a Russian who won the Giro d'Italia in May.

Other riders with outside shots include Leipheimer, Kloeden, Sastre's Saxo Bank teammate Frank Schleck and American Christian Vande Velde, the leader of Garmin-Slipstream who crashed out of the Giro with two broken ribs.

And even though he's 37, and consigned by Bruyneel to be a support rider for Contador at least from the start, Armstrong can never be counted out.

He finished a strong 12th in the Giro, and his rivals know that the man once known simply as "The Boss'' has an unparalleled ability to dominate minds in the pack.