In his books about cycling, cancer, fame and family and how they have intertwined to make him who he is, Lance Armstrong, the seven-time Tour de France winner, delves into fine detail about the roles his top teammates played on his champion Tour teams.

He talks about how the riders on his squads became as close as family and how George Hincapie, his road captain and longtime lieutenant, grew to know him the best.

“There have been times when I’ve practically lived out of the same suitcase with George Hincapie,” Armstrong said in “Every Second Counts.”

“In cycling we’re on the side of a mountain for weeks, in small hotel rooms, sharing every ache, and pain, and meal. You get to know everything about each other, including things you’d rather not.”

Those things he and Hincapie learned about each other are now at the center of yet another doping scandal involving Armstrong’s Tour-winning teams.

Because Hincapie is considered a credible and reluctant witness, his testimony could be the most damaging evidence against Armstrong, who is accused of doping and playing a key role in a vast doping conspiracy.

According to people with knowledge of the case, Hincapie has told the U.S. Anti-Doping Agency about systemic doping on Armstrong’s teams.

“There are certain riders who, you know, ooze respect, and George is one of them,” said Stuart O’Grady, an Australian rider who has raced against Hincapie for more than 20 years. “I don’t think anyone dislikes George. He’s just an all-around nice guy.”

The details of what Hincapie, 39, told antidoping authorities remain a mystery – though it could become public if Armstrong’s doping case goes to arbitration. Armstrong’s lawyers have filed a federal lawsuit to stop the antidoping agency’s case from moving forward with punishing him. He faces a lifetime ban from Olympic sports and the loss of his Tour titles.

If Hincapie does testify, his story has the potential to be one of the starkest, most jarring revelations in a sport known for its code of silence regarding doping.

Out of all of Armstrong’s teammates, Hincapie is likely to know more about the behind-the-scenes activity on their squads than any other rider: He was the only one to be by Armstrong’s side for every one of the Tour victories.

Joe Papp, a former pro cyclist and convicted steroid trafficker-turned-antidoping advocate, said Hincapie’s word will be “unimpeachable” and “will finally lead people to the point where they don’t believe Lance is innocent anymore.”

Armstrong, who has denied ever doping, did not immediately respond to a request for comment.

At first, Hincapie did not come forward voluntarily to provide information about the doping on Armstrong’s teams, said two people involved in the investigation.

He was given a subpoena to testify to the grand jury in the federal investigation of Armstrong for doping-related crimes, an inquiry that lasted two years before closing last February. Instead of testifying before the grand jury, Hincapie cooperated with the inquiry and gave sworn statements.

He then provided evidence about the systematic doping on Armstrong’s teams to the antidoping agency, which last month charged Armstrong with doping and playing a key role in the doping scheme.

If Hincapie admitted his own doping while helping uncover the principals in a larger doping plot, he could receive a reduced ban from cycling – perhaps six months, or even no ban at all, rather than the usual two-year ban for first-time offenders. If he is asked to testify before an arbitration panel and declines, however, he could face a stiffer punishment.

Because Armstrong has never officially failed a drug test – he tested positive at the 1999 Tour for banned cortisone, but later produced a doctor’s note for it – testimony like Hincapie’s will be crucial to the antidoping agency’s case against him and several team officials who are also charged with doping violations.

The agency said it had 10-plus riders whose testimony would bolster its case, but what sets Hincapie apart from some of those other cyclists who have given evidence – like Floyd Landis and Tyler Hamilton, who have admitted to doping and taking part in the doping conspiracy – is that Hincapie has yet to admit publicly that he had used performance-enhancing drugs.

Those who know Hincapie say he is likely tormented about his role in the case. They say it goes against everything ingrained in him as a gregario, which, in cycling terms, is a rider who sacrifices himself in the service of the team leader by doing things like sheltering that rider from the wind or protecting him from attacks.

Bob Stapleton, Hincapie’s former team owner of the HTC-Highroad squad, said it would be “a terrible conflict” for Hincapie to speak out against a teammate.

“He’s a guy who fundamentally wants to do the right things, but he is also fantastically loyal,” Stapleton said. “But when George talks, people are going to listen. You’re talking about the most liked and most respected American cyclist, maybe ever. We called him Captain America, for all the good reasons.”

Hincapie’s life has had a fairy-tale ring to it. As the son of Colombian immigrants, Hincapie grew up in Queens and was inspired to race bikes because his father, Ricardo, had been a competitive cyclist.

His father, who worked in the cargo department of United Airlines for more than 30 years, never made it big. But George Hincapie went on to become one of the most accomplished riders in U.S. history.

He is a five-time Olympian, a three-time national road champion and is currently riding in a record 17th Tour. As a self-sacrificing worker bee, he has helped three riders – Armstrong, Alberto Contador and Cadel Evans – win Tour titles.

In a documentary about Hincapie called “A Ride With George Hincapie,” Armstrong was asked what he considered Hincapie’s best attribute. “I’d have to choose loyal,” he said. “He was loyal to me as a team captain, he was loyal to me as a friend.

“He’s probably one of the nicest humans to walk the planet.”

In 2002, Hincapie and his brother, Rich, started a now successful cycling apparel company, Hincapie Sportswear. They employ several of their relatives in the company’s factory in Colombia. A year later, Hincapie met his future wife, Melanie Simonneau, on the awards podium at the Tour when she worked as a hostess there.

“The Tour brought me everything,” he said in June when announcing that he would retire this fall.

At this Tour, when Hincapie was asked about Armstrong’s doping case, he did not confirm or deny his involvement, simply saying: “I’m sad he is going through this. He’s done so many things for the sport. His accomplishments are incredible.”

Hincapie and Armstrong first met when they were scrawny teenagers headed for the national team. They became teammates on the Motorola squad in the mid-1990s and stayed together on the U.S. Postal Service squad and, finally, on Discovery Channel squad, on which Armstrong won his final Tour, in 2005.

Throughout it all, Armstrong was the frontman and star. Big George Hincapie, at 6 feet 3, 165 pounds, was the ever-present teammate who often paved the way to Armstrong’s success.

He was the ultimate setup man. His job was to pull Armstrong through the flats by riding in front of him and then deliver him to the bottom of the mountains, where the team’s pure climbers would take over.

Davis Phinney, the first American rider to win a Tour stage, said he remembered seeing Hincapie at the 2004 Tour, leading the Postal Service team up a climb in the Pyrenees. The image of Hincapie at the head of the pack, toiling as sure as a machine, has stayed with him.

“When we saw those guys go by, with the speed that they carried and with George out front just giving his all for the good of the team, setting up Lance perfectly for what was a stage victory, it was just so impressive,” Phinney said. “But that was George. What made people like him even more was that he did it all in the service of someone else.”

While the five other Americans on Armstrong’s victorious 1999 Tour team eventually left for individual success, Hincapie remained at Lance’s service.

“I’d do anything for the guy; he’s like a brother to me,” Hincapie said in 2009, during a break Armstrong had taken from the sport. Armstrong also has called Hincapie his “best bro in the peloton,” a guy to whom he spoke at least every other day.

Now, though, Hincapie – the only rider mentioned by name on the dedication pages of both of Armstrong’s main books – says they haven’t spoken “in a while.”

Jon Brand contributed reporting from St.-Jean-de-Maurienne, France.