Shortly after crossing the finish line, Michal Kwiatkowski collapses into a heap. He sits on the asphalt, leans against a fence, and wipes the sweat from his face. While a growing number of reporters gather around the Polish rider, he takes a slug of fluid from his water bottle. He has no eye for the picturesque backdrop of the Col d'Izoard, 2,360 meters (7,743 feet) above sea level. His gaze is empty, but he still has a lot to say.

He had given his all on the stage that just ended, protecting his captain Chris Froome from attacks from the competition, while pulling away from weakening opponents - until there was nothing left to give. At one point, Kwiatkowski swerved to the right, stopped for a moment, collected himself before slowly carrying on. His job on the mountain stages is to set the pace for Team Sky. Kwiatkowski is one of the most powerful classics riders in the world and won the world championship in 2014. He is at the heart of Team Sky's success, in which first-class riders sacrifice themselves in the interest of giving Chris Froome the best-possible chance to win.

The team factor

The plan is working. On the 2017 Tour, the team factor is much more decisive than in previous years. Froome is not as dominant as he used to be. He pretty much controls the race, but he is no longer in a class of his own. At Peyragudes, opponents managed to overtake him on a steep section and he lost the yellow jersey.

"It was a tough moment for us, and then we had to work hard, to put pressure on the opponents to get the jersey back," Kwiatkowski tells DW.

Working as a collective, they would later isolate Italy's Fabio Aru, who had managed to snatch the yellow jersey away from Froome despite the fact that he doesn't have a strong team around him. And having a strong team that makes all the difference: Sky has been dominant not because it has the strongest captain, but because of its outstanding teamwork.

"We ride smart," Kwiatkowski says. "(Romain) Bardet, (Rigoberto) Uran and Aru had to try something to make up time ahead of the time trial. We could just react and control the field."

And this tactic was also in play on the Izoard: Spaniards Mikel Nieve and Mikel Landa, along with Michal Kwiatkowski rode the competition ragged.

"We were just doing our job," says Nieve. "We trained incredibly hard as a team in preparation for this."

"They have the biggest team, the biggest budget, the best riders - they are simply the best at the moment," says Oliver Naesen. Yet again, the Belgian champion, with his French AG2R team had mounted a challenge to Sky - in vain, as it turned out. His captain, Romain Bardet, managed to pull to within just 23 seconds of Froome. However, in the time trials, to be held on the penultimate day, Froome had the upper hand.

"You have to hand it to them. Sky invests a lot in the details and gets the results," says Naesen, who aims to take small steps towards the tip rider in the next few years. After all, the one thing Team Sky can't stop is getting older. 

Lingering suspicion

For now, at least Sky's pre-eminence seems to be assured. With the exception of 2014, when Froome had to retire due to injuries sustained in a crash, the Sky team has functioned like a well-oiled machine. In fact, it has been so good that it has raised suspicions in some circles.

The watt values that Froome is believed to be generating have raised some of these suspicions,  even if these estimates were based on a few assumptions. However, there has been something of a dark cloud over the team since the affair involving a mysterious medicine pack for the then-captain of Team Sky, Bradley Wiggins. The affair remains dubious, despite the team's general manager Dave Brailsford denying any wrongdoing prior to the Tour. More transparency would certainly help the British team improve its credibility on the issue.

This isn't in keeping with the Sky model, though. The strategy of the team, which has an annual budget of 35 million euros ($40.8 million), is based on achieving "marginal gains" aimed at giving its riders an edge on the competition. And they aren't very open about how they achieve this.

Whether it's the equipment, diet or the training - Sky does its own thing and protects some of the secrets of its success as if they were the Holy Grail. When the Tour got underway in Düsseldorf, the competition was taken aback when they discovered that the Sky team's outfits had special aerodynamic cushions aimed to shave a few seconds off their times, and as it turned out, Froome and his teammates were faster than the competition.

They will probably use these outfits again on the penultimate stage, a time trial in Marseille. If everything goes according to plan, Chris Froome will celebrate his fourth overall Tour victory one day later in Paris. And there is good reason to believe it won't be his last, either.