The question no cyclist can escape: Why should we believe you're clean?

NARBONNE, France -- British sprinter Mark Cavendish, his face ruddy from sunburn, exertion and exhilaration, sat with a microphone in his hand, silent for almost a full minute, clearly wrestling with conflicting emotions.

Cavendish had just won his third Tour de France stage by doing what he does as brilliantly as anyone in the world: shooting the gap at the front of the peloton like a kayaker slipping between boulders in boiling whitewater, then firing the afterburners to finish ahead of the dozen or so riders who are in his class.

His performance is extraordinary for a 23-year-old competing in his second Tour. Associated Press writer Jamey Keaton was within his rights to ask the very personal question on the mind of everyone who has witnessed it, just as the Team Columbia star was within his rights to take the time to compose himself before answering it.

Why should we believe any rider is clean, including you?

"In any aspect of life, I think you're going to get people who think they're cleverer than the system," Cavendish said finally.

"I don't want to tarnish the sport I love. Maybe the people resorting to doping don't have the passion for the sport that I do."

Cavendish, along with overall Tour leader Cadel Evans of Australia and many other riders, directors and managers in the race caravan faced this discordant music Thursday thanks to the latest, and in many ways most aggravating, revelation of a positive doping test result at the 2008 race.

French police escorted 24-year-old Italian climbing specialist Riccardo Ricco from the Stage 12 start in the small town of Lavelanet after the national anti-doping agency announced an initial positive result for what is being referred to as a "new generation" of the blood booster erythropoietin (EPO).

In a mannered touch, a gendarme in the group that came to collect Ricco actually knocked at the door of the Saunier Duval team bus rather than kicking it down, SWAT-style. (As the officers waited for him, one remarked to a reporter, "Everyone has to make a living.") Another officer put his hand on Ricco's shoulder to prevent him from bumping his head as the rider ducked into a team car, and he was swept away to boos and hisses from the crowd. Ashen-faced team officials announced they were pulling the team from the race. Saunier Duval's roadies reracked the bikes on top of their cars and that was it.

It was all very familiar for anyone who's been following the Tour lately, but the 168 riders and their entourages who rolled away from the start line that day couldn't help but feel as if they'd banged their heads against something much harder than a car roof.

"This one hurts," Team Columbia owner Bob Stapleton said from a car following the peloton that day, the wind rushing over and blurring his words. "It's painful. It's getting under my skin. It's a question of attitudes and values."

The substance tentatively identified in Ricco's system is known as CERA, or continuous erythropoietin receptor activator. Like most doping agents, it's a medication intended for healing purposes that has been twisted to suit the shady side of sport.

CERA was developed to treat anemia in people with kidney disease and has a longer half-life than "regular" EPO, which means it's effective in once-monthly injections as opposed to weekly or even more frequent ones.

In other words, a new generation of drug for a new generation of dopers. It does make you wonder about the supply chain. Do young riders spend hours surfing the Internet in search of the latest thing? We think not. Someone, whether it's black marketeers from pharmaceutical companies or the witch doctors and trainers who attach themselves to athletes like literal leeches, spreads the word in the peloton. "Hey, got something new for you. They're not onto it yet." Someone, somewhere, persuaded riders that the longer-lasting action of CERA would give them an invisible tailwind.

Cycling followers often refer to the races within the race at three-week Grand Tours. The sprinters have their own competition, the climbers theirs, the under-25 riders theirs. Apparently, there's now another competition where no standings are being kept, for good reason. The private sector labs that develop medications like CERA are cooperating with anti-doping agencies in finding ways to detect their altruistically intended products. It could bring down the gap between the cheaters and the testers.

But as Cavendish and Stapleton alluded to, the truly remarkable thing about Ricco's transgression, if proven, is its breathtaking arrogance and selfishness. Ricco, second in the Tour of Italy and a double stage winner here, openly professed his admiration for the tainted career of late 1998 Tour winner Marco Pantani. During the climb of the Col d'Aspin in Stage 9, Ricco accelerated away from the strongest and most experienced men in the race at such a rapid rate that it instantly raised questions about whether he was doping. His teammates Leonardo Piepoli (fired by Saunier Duval for unspecified reasons Friday) and Juan Jose Cobo looked similarly out of place in their show of strength on the Hautacam climb a day later.

"The unfortunate thing is that we are learning that things that look too good to be true are too good to be true," Garmin-Chipotle's David Millar observed in a sentiment shared by most in the peloton, with or without Millar's complex history of doping sin and redemption.

It's hard to imagine how Ricco or anyone can delude himself into thinking he can get away with this behavior given the increase in the amount and precision of testing and the much harder scrutiny that -- like instant exit polls at election time -- now immediately follows explosive performances like his.

Garmin-Chipotle's team physiologist, Allen Lim, quietly crunched numbers after the stage that showed how unlikely Ricco's ascension rate was, and he was not alone. While such analyses in and of themselves are not evidence, at the very least they will attract the searchlights of anti-doping authorities who are unabashedly targeting prime suspects.

On an emotional level, it's also hard to imagine the level of cynicism, denial and risk addiction it would have taken for a dirty rider to be unmoved by the pre-Tour meeting called by race director Christian Prudhomme, a man partial to bombast who nonetheless excluded media from this particular gathering.

Garmin-Chipotle owner Doug Ellis was there. "He made a very strong appeal, saying, 'This is our sport, our monument to take care of. Everyone has the power to bring it down,'" Ellis said. "I like that message. I believe in that message. But for self-interest, people are bringing down an institution that's bigger than any one guy's win or his career.

"What are they thinking?"

Much has been written about the commitment of teams like Columbia, Garmin-Chipotle and Team CSC-Saxo Bank to the anti-doping cause and their independently monitored blood profiling programs. But perhaps the smartest thing these teams have done is find honest ways to appeal to the same base competitiveness in elite athletes that sometimes leads them to cross ethical lines.

What separates these riders from the rest of us is not only their physical gifts but their incredible capacity to drive, motivate and discipline themselves. If a rider believes he has an edge, he does; so each of these teams has gone to extremes to experiment with innovative training methods, equipment and psychological support. CSC-Saxo Bank owner Bjarne Riis instituted offseason survival camps to bond his riders. Columbia has brought in strength and biomechanical coaches from other sports and has its riders sit in inflatable cold plunge pools after stages. Garmin-Chipotle riders don ice vests while warming up for time trials and pull on compression space boots and helmets after stages to promote better circulation.

No detail is too small for the concept vetters on these teams. It all adds up to a process that should be a lot more satisfying than living in the clandestine world of injections, transfusions and drips.

Ricco might have to wait a while to find out what that's like if he's convicted, treated like a common criminal by the French justice system (he faces a maximum $5,000 fine and two years in jail for use and/or possession of doping substances) and suspended from cycling for the mandatory two years. But it all starts with wanting to ride straight and win clean. If team directors could predetermine that predilection, they would, but that's one area of human chemistry no test can plumb.

Cavendish noted after his wheel-length win that he wasn't able to open up the kind of margin he had in his first two stage victories. "It shows how tired I am," he said, without show or self-pity. That is supposed to happen to mortals over a three-week race, no matter how fit they are.

The Olympics-bound sprinter had a close call early in Stage 10, when, riding on the flats through a wooded area, a soccer ball rolled out onto the course. Cavendish and Garmin-Chipotle's Danny Pate crashed as a result but weren't seriously hurt.

"It's a beautiful sport," Cavendish said. "With the pleasure comes the pain."

That pretty much sums up the state of the Tour and cycling right now: grim pleasure in watching the incremental steps toward progress, pain at the knowledge that a certain number will refuse to go along.

Bonnie D. Ford covers tennis and Olympic sports for ESPN.com. E-mail her at bonniedford@aol.com.