There's an inescapable appeal to the Tour de France - the scenery, the pageantry, the suffering of the riders, which somehow appears romantic. It is one of sport's greatest spectacles, particularly when the roads turn heavenwards in the high mountains. Unfortunately, it also provides many of sport's darkest secrets and worst villains.If you haven't already thought "oh, that annual gathering of the cheats", then you're in a minority yet to be affected by the cynicism that cycling has earned through countless doping scandals.The Tour's history is punctuated by cheating. Started in 1903 as part of a newspaper "conflict", the first race was enormously popular, but inspired such passions that rival fans beat up riders, some of whom also tried to sabotage their opponents to win the substantial prize money.Doping soon followed, in the form of wine and strychnine (used in pesticides, but which apparently dulls pain). World War 2 delivered amphetamines to keep pilots awake, but they were handy for cyclists needing to override fatigue and pain. Blood doping, and then EPO, which improves oxygen delivery, replaced those stimulants in the early 1990s, and we've been fighting to escape that orbit ever since.Yet, despite all this, the Tour retains a sense of wonder. Ten years ago, I attended my first Tour, and followed the race around, riding many of the final mountain climbs along with thousands of other enthusiasts.I stood on the legendary climb of Alp d'Huez, along with allegedly a million others to watch an individual time trial, and I confess that when Jan Ullrich and Lance Armstrong rode by, I ran alongside and cheered loudly, even though I knew then that they were pharmaceutically enhanced.Perhaps there is something about the Tour that allows for this cognitive dissonance, the ability to enjoy the spectacle while retaining the knowledge that all is not as it seems.The 2015 Tour de France will be no different. It brings together the best four cyclists of this generation - Vincenzo Nibali, Alberto Contador, Chris Froome and Nairo Quintana. We expect attacks, aggression and fireworks, assuming they all navigate the first 10 tricky days of the ride.It is impossible to call, with each having claims on their Tour prospects. Behind them, a group of five or six challengers lurks, waiting for a breakthrough, and so this Tour, more than any in recent memory, is worthy of newspaper column centimetres for the right reasons.Yet there's still that nagging shadow, and for all the talk of change since Armstrong's era, I fear what has changed is not the principle, nor the practice of doping, but rather the methods. Advances in anti-doping, though not perfect, have certainly been made.Extra scrutiny, both from anti-doping authorities and an increasingly aware and alert media and public, have steered what riders can get away with in a different direction.Rampant doping has been replaced by micro-dosing to fly beneath the anti-doping radar, and clever drug combinations to help riders lose weight and recover faster are used.Wealthy and ambitious teams are venturing into the grey areas for every advantage. It's as if "blunt force" doping has been replaced by surgically precise doping, resulting in performances that now approach those of the doping peak. You can decide if that's a positive development or not.Despite this, I eagerly await the racing with the enthusiasm of my 2004 self. It's the Tour, after all. As for a prediction, your guess is as good as mine, but if Nibali is back in his whistling-up-the-mountain 2014 form, he's an outsider - bookies have him fourth - worth a flutter. But then, who'd bet on cycling?..