There are over 3,500 kilometers to be covered in the race and brutal climbs such as Mont Ventoux, where British cyclist Tommy Simpson died in 1967, to be tackled in three weeks of lung-busting action.
Such is the severity of the race -- which starts Saturday in Normandy -- the temptation to take short cuts has proved too strong for the likes of disgraced seven-time winner Lance Armstrong -- the most notable of a long list of cycling drug cheats.
But it now appears that the cheaters have fastened onto another ruse to fast track their way to the finish -- mechanical doping.
It involves fitting small, undetectable motors in their bikes, utilized at key moments such as the ascent of the Ventoux or the finish to a stage, to gain that extra edge.
Rumors have been rife for several years that these devices were being deployed, with various unsubstantiated allegations surrounding their use in cycling's top races, including the Tour.
They allow riders to produce extra power or watts for no extra effort or revolutions of the pedals.
Another, more sophisticated and more difficult to detect method, involving special batteries in the rear wheel to get a few extra watts, is also believed to have been developed.
Until recently, this was just hearsay, but in April Belgium's Femke Van den Driessche of Belgium was caught using a motorized device during the European women's Under-23 Cyclocross Championships.
The 19-year-old Belgian protested her innocence, claiming she was using another rider's bike
, but it did not wash and placed organizers of the Tour de France and other sports officials on red alert. She was banned for six years.
"This problem is worse than doping. The very future of cycling is hanging in the balance," French Sports Minister Thierry Braillard told the Journal de Dimance newspaper.
Tour de France chief Christian Prudhomme agreed and announced earlier this week that a series of special measures were being put in place in an attempt to beat anyone contemplating motorized cheating.
The expertise of the French Atomic Energy Commission has even been called upon to design a thermal imaging camera, which will be attached to iPad style tablets.
These will be placed at undisclosed points on the race route in an attempt to act as a deterrent to any motor assisted riders. Organizers are also promising other measures but not releasing the full details as they try to keep ahead of any malfeasance
"Protecting the Tour de France is the most important thing. We now have a real deterrent. The cycling world must form a united front to fight against cheating rather than setting off in a dispersed manner," Prudhomme told reporters.
Brian Cookson, the president of cycling's world governing body, the UCI, said the measures sent out a "clear message" that officials were taking this new threat seriously.
This year's Tour, the 103rd edition of cycling's most famous race, will see the peloton return to the Ventoux, nicknamed the "Giant of Provence," and it is likely to be one of the keys to victory for the leading contenders.
A brutal seemingly never ending climb on unforgiving exposed slopes -- it has witnessed triumph and tragedy in equal measure.
Failure to measure up to the punishing 22.7 km summit finish on Bastille Day July 14 will see the yellow jersey slip from their fingers.
This year's favorite, Chris Froome of Team Sky and Britain, clinched his 2013 victory on Ventoux and has been rehearsing his lines again in preparation.
He will need no reminding that his countryman Simpson met his death on the climb while pushing his tortured body beyond human limits in a bid to win yellow nearly 50 years ago.
There is a monument in memory of him on the way to the top and recreational cyclists trying to emulate their professional heroes often stop to pay homage.
Froome and the other leading hopes such as Colombia's Nairo Quintana and two-time champion Alberto Contador will ride past the spot at sweat-filled speed but will be only to aware of the imposing nature of the climb and its place in cycling folklore.
It's one of the reasons why, despite France being gripped by Euro 2016, its national obsession with La Grand Boucle will not be diminished even though there has not been a home winner since Bernard Hinault in 1985.
Millions will line the route and the summit finishes, where the race is effectively decided, will see avid fans camp out for days to find a viewing spot ahead of the peloton's fleeting arrival.
The Mont Ventoux stage has a special resonance. It will be the 10th summit finish on the "Bald Mountain," so labeled because of the roads and surrounds stripped of greenery with a lunar-like landscape of bare rocks at the top.
One of four summit finishes, the final one to Mont Blanc, and nine mountain stages plus two individual tests against the clock will decide the eventual outcome.
Froome finished fully 29 seconds ahead of Quintana on Mont Ventoux in 2013 and with such a strong team in support is favorite to clinch a third Tour victory this year.
Should he do so, the British rider will become the first man since Miguel Indurain in 1995 to win back to back Tours.
Of course, Armstrong won seven in a row, but was stripped of his victories once the full extent of his doping misdemeanors were revealed.
Saturday will see the 22-team 198-strong peloton begin its 3,535km (2,197m) journey from the UNESCO World Heritage site of Mont Saint-Michel and finish in the Paris three weeks and 21 stages later.
The recent terrorist attacks in the French capital have prompted a massive security operation for both football's Euro 2016
and the Tour.
There has been a state of emergency in place since 130 people lost their lives on November 13 last year, with a French football international at the Stade de France among the targets.
For the Tour, it means special operation gendarmes of the GIGN, France's special forces, will be among over 23,000 police deployed along the route.
They could have their work cut out given the race attracts 12 million spectators, who line the narrow, twisting mountain routes and crowded city streets.
"Ready to intervene at any moment if needed," Bernard Cazeneuve, the French interior minister, has said. "Everyone understands that this year the Tour de France is taking place in a particular context," added Cazeneuve.
Organizers and the French government will be hoping that the iconic final stage, which finishes on the Champs Elysees on July 24, will be taking place without the race having been tarnished by doping -- mechanical or conventional -- and without a major security issue.
The battle for the overall race winner and yellow jersey will have been settled, but the other major jersey, the green of the points winner, may still be in the balance.
Reigning world road race champion Peter Sagan, who is in Contador's formidable Tinkoff-Saxo team, has won it four straight years, relying on consistent finishes on each of the Tour's flatter stages.
German pair Marcel Kittel and Andre Greipel, who won four stages in sprint finishes last year, will also be among strong contenders for the green jersey as well as the prestigious final stage victory.
Britain's Mark Cavendish, winner of the points classification in 2011, claimed four straight wins on the Champs Elysees from 2009-12 but is still searching for a victory on the opening stage.
Cavendish has made crossing the line first at Utah Beach after 188km from Mont Saint-Michel his major goal and with it the honor of donning the yellow jersey of overall race leader for the first time.