The Australian’s online service reported that Schleck returned an adverse analytical finding—also known as a positive test—for the diuretic Xipamide.
The result is from a sample taken after the 217-kilometer, Stage 13 ride from Saint-Paul-Trois-Châteaux to Le Cap d'Agde.
While diuretics are not in themselves performance enhancing, they have long been used as a masking agent to hide actual doping metabolites by dilution through increasing the volume of urine produced.
It has also been suggested that they aid weight loss, which may help a rider in the mountain stages. However, diuretics reduce hydration levels, which is not a smart thing for a pro cyclist to do.
Besides, diuretics are fast-acting and Stage 13 was a flat stage, putting paid to the weight loss for climbing theory.
While Schleck will not be charged with anything until the "B" sample has been tested, and he was not kicked off the Tour, he was immediately withdrawn from the race and faces suspension from his team, should the second sample also return a positive result.
This will be a bitter blow for a team already struggling with rumours of financial difficulty and unpaid rider salaries.
Although the team’s owner, Leopard SA—a Luxembourg-based company—deny these rumours, it has been reported by CyclingNews.com that Jakob Fugslang is suing for unpaid wages and three other riders have officially notified the UCI of non-payments, also according to CyclingNews.com.
Schleck’s positive test now also casts a shadow over younger brother Andy, who inherited the 2010 Tour de France winner’s jersey when Alberto Contador was stripped of his title for doping. The Schleck brothers are a formidable tag team and their performances are invariably at their best when they are riding together.
Both brothers featured on the General Classification podium at the 2011 Tour—Andy second and Frank third, behind Cadel Evans
While the younger Schleck has never tested positive for any banned substance, the incredibly close relationship with Frank will perhaps forever leave a question mark over his victories—however unfair that may be.
The Schleck name has been a huge part of the Tour’s recent history and this positive test will again seriously damage the reputation of not only the Tour, but cycling in general.
That’s something that the race, and the sport, could well do without.