GAP, France – Through the picturesque countryside and the strenuous mountain climbs, suspicion rides along with the cyclists at the Tour de France, despite the largest anti-doping sweep in years on the eve of the fabled race’s start.

“It’s not because there was a big kick to their ant hill that we can let ourselves think it’s finished, and that everything has been solved,” said Jerome Pineau, a French rider with the Bouygues Telecom team.

The house-cleaning right before the July 1 start removed some of the top favorites from the first Tour of the post-Lance Armstrong era. But some experts don’t believe the recent doping expulsions will remedy the sport’s doping culture revolving around suspect doctors, unscrupulous team coaches and riders hoping for an extra edge.

And if there’s any time when riders may be tempted to rely on blood doping to boost performance, some experts say, it’s now – as the Tour heads into the final mountain stages with several cyclists still in contention for the famed yellow jersey.

That’s just what happened to nine riders after their names emerged in a doping probe centering on a Spanish doctor. The doctor, Eufemiano Fuentes, was arrested in May after Spanish police seized drugs and frozen blood at a Madrid clinic.

“I’m sure there are still other Dr. Fuentes’ in the world,” Pineau said.

The best-known riders often face the most scrutiny.

Ullrich had 10 anti-doping controls by various agencies while training for the Tour, but even with such controls, the cat-and-mouse game is likely to go on.

“It’s human nature to try to cheat the system. It happens in cycling, it happens in business,” said Australian Michael Rogers of T-Mobile. “You can’t control everyone.”