But is the Tour still worth taking seriously as a sports event?
The fall of Lance Armstrong in the past year, along with other dopers who ruined the credibility of cycling and its showcase race, has opened that question to debate like never before.
From the outset in 1903, when journalist Geo Lefevre and his editor Henri Desgrange, hatched the idea of an endurance race around France to boost sales of their newspaper, L'Auto, the Tour has always been part-publicity stunt, part-genuine sporting contest.
Then, as now, it sucked in spectators with the theater both gruesome and inspiring of men made to suffer on bicycles.
And even now, at the sport's nadir, the Tour's essential charms to fans and sponsors remain the same: roads, mountains, the beauty of France and men willing to push themselves to extremes.
The timing alone in July when much of France is either vacationing or thinking about it makes it more than likely that the Tour will be still be around for its 200th edition.
The competition is always colorful if not always believable, a fun excuse for sleepy villages to come alive and a free summer spectacle for holiday-makers. The millions of people who line the route largely don't seem to care how many riders are pumped up on banned drugs and blood transfusions. Just as long as they see the spandex-clad racers zoom by and get a good picnic spot and freebies from sponsors, whose floats precede the riders, tossing out sweets, cheap sunhats and bite-size packs of cured sausage. Tour spectators, surveys suggest, make a day of it, often coming in groups and spending six or more hours by the side of the road.
Their presence and media coverage in a month when other sports, including soccer, are largely dormant means the Tour remains worthwhile for sponsors, which argues for it continuing to hold a special place in athletic calendar.
French lottery and gaming operator La Franaise des Jeux spends €9.5 million ($12.5 million) per year on the cycling team that bears its name. But in French television and newspaper publicity, it recouped nearly that same amount from the team at the 2012 Tour, when its rider Thibaut Pinot finished 10th and won stage eight, said FDJ sponsorship director Thierry Huguenin. Nestle Waters' sponsorship manager, Francoise Bresson, said it spends 3 million to 5 million euros ($4 million to $6.5 million) each year to have its Vittel brand plastered over the end of each day's stage, generating publicity in France and overseas that otherwise might have cost at least 10 times that amount to buy. The Tour makes a profit for its owners, ASO, but the company won't say how much.
"For its 100th edition, it is in rude health," Bresson said in an interview about the Tour. "Doping has no or little impact. The sporting exploits dominate and the festive dimension. In these times of crisis, there aren't that many free sporting events which are a pleasure for the spectators."
Doping also isn't new to the Tour. The intense physicality of the race long encouraged it. As far back as 1924, the Pelissier brothers, Henri and Francis, were telling famed French journalist Albert Londres that they dosed up on cocaine, chloroform and assorted pills.
"In short," said Francis, "we run on 'dynamite.'"
Armstrong might have scoffed at that. Dynamite? Amateurs. By 1999, when he and his U.S. Postal Service teammates hijacked the Tour, riders had become lab rats. Drops of testosterone, shots of cortisone, human growth hormone to help build muscle. Transfusions of blood and injections of erythropoietin, a hormone that stimulates the body to produce oxygen-bearing red blood cells and is used in medicine to treat anemia. Engrained, widespread and relatively risk-free because drug testing was so poor, doping became more of a necessity than a choice in professional cycling.
Scientists estimated at least 80 percent of riders in the grand tours of France, Spain and Italy were manipulating their blood. It became as routine as "saying we have to have air in our tires or water in our bottles," Armstrong told interviewer Oprah Winfrey this January, when he finally confessed, after years of lawyer-backed denials, that he doped for all seven of his Tour wins from 1999-2005.
Those titles have now been stripped from him and not reattributed, blowing a hole in the Tour's roll of honor as large as that left by World War II. Armstrong, his doping peers and cycling's woeful failure to unmask them earlier blew even larger holes in the credibility of the sport and its administrators. The ultimately bogus tale of the cancer survivor who conquered the Tour with willpower and sweat had drawn new interest and fans to what had mainly been a European sport and its most famous race. Now that the U.S. Anti-Doping Agency has jimmied open the secrets Armstrong kept hidden for so long, how many fans have been lost to cycling forever?
"What is disappointing is the amount of people that say, 'You know, look, I've lost faith in it, I don't believe in it anymore. Because, you know, fool me once, fool you. Fool me twice, fool me,'" Jaimie Fuller, owner of sportswear manufacturer and cycling sponsor Skins, said in an interview. "People really felt let down about the fact that it just keeps biting us."
How many riders are still doping? Only they know. Cycling's anti-doping program is more believable than it was when Armstrong was cheating with impunity. Cycling teams, race organizers, the sport's governing body and even the riders themselves fund the drug testing that is arguably more rigorous than that faced by professionals in tennis, the NBA, the NFL or Major League Baseball. Riders in the top tier of teams were tested an average of nearly 12 times in 2012.
But no one is foolish enough to say all dopers have been weeded out.
In May at Italy's grand tour, the Giro d'Italia, Vini Fantini teammates Mauro Santambrogio and Danilo Di Luca tested positive for EPO. Alexander Serebryakov also was positive for EPO in a test in March. Another Russian, Nikita Novikov, tested positive for a muscle-building drug in May. Their respective teams Euskaltel-Euskadi and Vacansoleil are among the 22 riding the Tour.
Optimists say such incidents demonstrate that cycling is now doing more than other sports to confound cheats, not that it has more cheats.
"You only find what you look for," Tour director Christian Prudhomme said in an interview. "When the police catch thieves, we congratulate them. When cycling catches cheats, people say, 'there are still things going on.'"
Fuller said that, "If I had to put numbers on it, my intuition tells me that six or seven years ago it was probably 90 percent of the peloton (that was doping), 80 to 90 percent. Today? I don't know, might be 20 percent, might be 15 percent. Is that good progress? Yes. Is it enough? No."
Some sponsors have already bailed out. Dutch lender Rabobank ended 17 years of cycling sponsorship last October, pulling 15 million euros ($20 million) per year from the team that bore its name. The bank said it was no longer convinced that cycling can clean up.
Auto manufacturer Nissan disassociated its name from another team that used to employ Johan Bruyneel, Armstrong's mentor identified by USADA and his ex-teammates as one of the organizers of systematic doping on their U.S. Postal and Discovery Channel squads.
The HTC-Highroad team folded at the end of 2011. Owner Bob Stapleton told cycling reporters that the investigations into Armstrong and into Alberto Contador, the Spanish rider stripped of his victory at the 2010 Tour for failing doping controls, featured in all his discussions with potential sponsors.
"This has been a hard period for cycling, anyone who denies that is off their rocker," said Jonathan Vaughters, a former Postal teammate of Armstrong's who now runs the Garmin-Sharp cycling team. "The bad news has hit and hit hard, and we've had to deal with it."
"It should have been dealt with a decade ago. It wasn't, so we had to deal with it now. And that's good. I think that sends the correct message, to fans, to the athletes, to the teams that, 'You know what? Even if you think you might get away with it, you won't, because it can come back 10 years later and still find you.'
"The sport has been forced to digest the reality of its past and that's good," he added. "Sometimes you need surgery to get the wound to heal and I think that's been the case here."