Cycling Tour de France doping scandalThe Landis affair may be the one finally to kill the Tour if action isn't taken, writes Shane Stokes

Floyd Landis remains innocent until the analysis of his B sample confirms the positive result, but if he is disqualified it will be the second time in the race's history the final Tour winner lost out.

Way back in 1904, during the second edition of the race, defending champion Maurice Garin was first overall at the finish in Paris. But the Frenchman was stripped of his Tour win when it was shown he had taken a train some of the way. The other riders in the top four - Lucien Pothier, César Garin and Hippolyte Aucouturier - were also thrown out, leaving fifth-placed Henri Cornet as the final winner.

Since then other top riders have been disqualified. Doping is the preferred method of hara-kiri. In 1978, Michael Pollentier was ejected while in the yellow jersey, the Belgian having been caught trying to cheat dope control by using a rubber bulb and tube containing someone else's (clean) urine.

Ten years later, another yellow-jersey wearer ran into trouble. Pedro Delgado - who finished second to Stephen Roche in 1987 - provided a urine sample that tested positive for probenecid, a kidney medication that can also act as a masking agent. The Spaniard escaped sanction and went on to win the race because the substance was not yet on the governing body's banned list.

Across the border, 1988 Tour de France winner Marco Pantani was ejected from the following year's Giro d'Italia (Tour of Italy) while leading the race.

A blood test taken from the Italian climber showed his haematocrit to be over the UCI's maximum limit of 50 per cent. While this is a health measure rather than a positive test, such elevated haematocrit readings are regarded as strongly suggestive of EPO use.

Other scandals to befall the sport include the 1967 death of Tom Simpson - due in part to doping - and the 1998 Festina Affair, named after the team ejected from the race after a car loaded with banned substances was stopped on the Franco-Belgian border. This squad included French favourites Richard Virenque, second in 1997, and the then-world champion, Laurent Brochard.

Earlier this year, Spanish police made a series of arrests in conjunction with the Operación Puerto investigation into blood boosting and doping among cyclists and other sportspeople at a clinic in Madrid. The fallout from this saw three race favourites, Ivan Basso, Jan Ullrich and Francisco Mancebo, prevented from starting on suspicion of being involved.

Also ruled out was Alexandre Vinokourov. He was fifth last year, and while there is no proof he himself doped, his team were implicated in the scandal and were thus ejected en masse.

This scandal and the news about Floyd Landis's positive A sample has meant Dublin's Pat McQuaid has had a tough start to his term as UCI president. McQuaid took over at the helm last September, and he told The Irish Times yesterday the fight against doping is now the overwhelming priority of his tenure.

"Floyd Landis has to be regarded as innocent until such time as the B sample confirms the result. But if that is positive I will be very, very angry," he said.

"I find it hard to believe that guys nowadays would continue to try to beat the system when the system has been proved to be working well. I would also have thought after the start of this year's Tour de France, with all the emphasis and the pressure on doping, that the riders would have ridden it clean."

McQuaid is under no illusions as to what a disqualification of Landis would mean. "It couldn't be any more serious for cycling," he admitted. "It would be a disaster for the Tour and indeed for the sport as well. The situation is intolerable.

"We will have to take some very hard decisions over the coming weeks and months, getting to the bottom of this scourge and get it cleaned up. This is now going to become a personal crusade of mine, I am determined to tackle it. We have to get rid of these guys for once and for all."

McQuaid knows this could be the last chance for cycling to really make amends. The Festina Affair was seen as a catalyst for change, but while there are signs that there is less institutionalised doping, it is clear the expected reformation didn't take place.

The Operación Puerto affair and the likely disqualification of Landis must be the beginning of real and complete change.

Otherwise, 102 years after Garin's train journey caused the first big scandal, the credibility of the Tour may be lost forever.