The men behind, and in front of, cycling's best rider

Nothing explains better why American cyclist Lance Armstrong is favored to wear the leader's yellow jersey in the Tour de France when it ends later this month than the fact that he was not wearing it Thursday.

That honor belonged to his US Postal teammate, Victor Hugo Peña, after a stunning display of cooperative cycling in a team time trial Wednesday propelled US Postal riders into the top eight places on the fifth day of the three-week race.

Teamwork, at which US Postal excels, will be the bedrock of Mr. Armstrong's record-equaling fifth consecutive Tour de France victory, if indeed he manages that feat, say cycling experts who watch more than just the stars who steal the glory of success.

"What's unique about cycling is that you are working together, like a team in football or any other sport, but only one rider actually wins," says Steve Bauer, a former Tour de France competitor. "One guy will step onto the podium in Paris, but the whole team deserves the accolades."

Still, riders in the nine-man teams competing in the Tour know their jobs and keep their priorities straight: to help in any way they can to push their strongest team- mate as high up the standings as they can.

When a French TV interviewer suggested Wednesday evening to George Hincapie, a US Postal rider, that he and his colleagues would now try to keep Mr. Peña at the head of the 196 strong pack, Mr. Hincapie was blunt. "The plan stays the same," he said. "We work for Lance."

Nor was Peña, the first Colombian rider ever to wear the legendary Tour de France yellow jersey, under any illusions about his ambitions. "I'm the consequence of what the team did right," he said. "For the moment I have the yellow jersey, but I will be passing it on."

What the US Postal team did right on Wednesday was to share the load evenly among its members, all of whom are powerful riders in good form. And in cycling, the load is pole position.

A rider out on his own, or leading the pack, bears the full brunt of any wind. Just traveling through still air, he is putting out 30 percent more energy to pedal at the same speed as a rider behind him, enjoying the benefit of his slipstream.

That means that the rider in front of the pack effectively "pulls" the train of cyclists behind him, setting the pace that best suits his team until a rival decides it is time to try to take control.

Each of the 20 teams in the Tour de France has one or two riders capable of winning, if not the overall race, a day's stage, or one of the special jerseys reserved for the best hill climber and sprinter. Those team leaders can count on assistance from their workhorse colleagues to protect them and pull them through the long slogs that make up much of the 2,218-mile race.

"Over days and days, energy expenditure is extremely important," says Mr. Bauer. "For Lance Armstrong, it's a question of conserving, conserving, conserving until he has to put it out" on critical stages in the Alps and Pyrenees.

At different times in the three-week race, Armstrong's support riders will play different roles. Some will ride ahead of and alongside him, protecting him from head winds and from other riders who might bump him in the crush of the peloton, or pack.

Others will stay toward the front of the peleton, keeping an eye on the leaders and chasing down any breakaway groups that might threaten Armstrong's overall race position by getting too far ahead of him in cumulative time. Others, still, will husband their strength until the mountains, where they are especially strong and can help pull their leader up the hills.

That was how Armstrong won the crucial first mountain stage in last year's Tour. One after the other, teammates Hincapie, Jose Luis Rubiera, and then Roberto Heras charged up the Pyrenees ahead of everyone else, carrying Armstrong in their wake and breaking the opposition with their pace. At the finish line, Heras could have won the stage, but his job was not to win: it was to block the one rival still keeping up so that Armstrong could cross the line first.

That kind of sacrifice "can be difficult," says Bauer, a Canadian rider who wore the yellow jersey 14 times during his career. "But the riders are professional, they have a job to do, and they are paid for it. Heras is still riding with Armstrong this year, so he must believe in his role."

If support riders are not allowed to claim the glory, they do share in the winnings.

Different teams have different ways of splitting up the season's prize money - some split it equally between all riders, some share it according to how many days a man has raced; others pay out extra to those who compete in the most prestigious races. But the more races your star teammate wins, the more money you earn.

Some riders' sense of sacrifice takes them to extremes. In critical situations they have been known to give up their bikes to leaders stranded by a flat tire. American Tyler Hamilton, lead rider for the Danish CSC team in this year's Tour, refused to drop out even when he broke his collarbone on the first day, so that he could help push teammate Carlos Sastre into a higher placing in the team trial.

And sometimes, teams break apart. Bauer remembers how in 1986 his team split down the middle between its French riders, who wanted to work for fellow countryman Bernard Hinault to help him win a record breaking sixth Tour, and the rest, who thought it was Greg Lemond's turn to win. In the end, Mr. Lemond triumphed, becoming the first American to win the Tour.

Rarely, though, does one team contain two potential Tour winners. The US Postal team has unusual strength in depth, "and on any given day, several of them are as good as Lance," says Bauer. "But over the whole Tour, Lance is king."