A familiar sense of disarray descended on Le Tour after pre-race favourite Alexander Vinokourov tested positive for blood doping. A sample taken from the Kazakh rider after his winning performance in a time trial stage showed traces of another person’s blood, a technique used to increase an athlete’s resistance to fatigue.

MSN Video - Le Tour: Vinokourov fails a drug test

As Vinokourov and his 8 Astana teammates immediately withdrew from the Tour, the sense of depression surrounding the race was about to intensify. Some riders, openly prepared to make a stand for clean racing, staged a brief sit-in on the start line of the 16th stage. Tellingly, controversial race leader Michael Rasmussen refused to join them. The Dane was jeered by fans in the wake of being dropped from Denmark's national squad for missing two out of competition drug tests. Hours after he powered to victory at yesterday's mountain finish, Rasmussen was sacked by his Rabobank team and quit the race, a sure sign his sponsors did not want to be associated with a discredited champion likely to be booed all the way to Paris.  

These events are another sad chapter in the history of Le Tour and the drug pedallers that have stained its credibility. Last year’s winner Floyd Landis was stripped of victory after testing positive for testosterone. 1997 winner Jan Ullrich was sacked by his T-Mobile team after being implicated in the Operation Puerto doping investigation. The cynicism surrounding cycling success is such that seven-time time Tour winner Lance Armstrong was subjected to a spiteful campaign by French newspapers suggesting he too had doped despite never once testing positive in his career.

Winning without glory

Without doubt, another world sport seriously affected by use of performance enhancing drugs amongst its leading performers is athletics. Most notoriously, Ben Johnson’s dominance of men’s sprinting in the late 1980s was brought to an abrupt halt after the Canadian tested positive for anabolic steroids. But making an example of the disgraced Johnson didn't stopped the cheats. In 2006, Olympic 100 metres champion Justin Gatlin failed a drugs test and was subsequently banned for 8 years. Twelve months earlier, sprinters Marion Jones, Tim Montgomery and Brit Dwain Chambers all failed tests after their association with California’s Bay Area Laboratory Co-operative (BALCO) was revealed. The founders of the clinic implicated the athletes after pleading guilty to charges of steroid distribution and money laundering.

Echoes of the BALCO scandal also permeated the America's most loved sport; baseball. Barry Bonds, arguably the sport’s biggest star, is poised to pass one of American sport's holy grails, baseball's all-time home run record. Bonds has never tested positive for steroids and, at the time he is alleged to have taken them, they were yet to be outlawed in baseball. But when a BALCO chemist admitted that Bonds had received performance enhancing drugs from his lab, the San Francisco slugger’s many achievements were forever tainted in the eyes of the American public.

For the millions that obsessively participate and watch sport in all its forms, the suspicion that the outstanding achievements that inspire us are not genuine is the greatest threat to historic events like the Tour de France and the Olympic games.

Have your say: can Le Tour's reputation recover?

But despite the short term shame generated by Vinokourov, Rasmussen and their ilk, the fact that the organisers of Le Tour are now proving consistently successful in rooting out the cheats offers some hope that, in the long-term, cycling’s biggest and most gruelling spectacle has some chance of regaining the trust of the millions of people who support it.