Olympic track gold medalist Geraint Thomas has transformed into a brilliant climber to help Sky's Froome deep into the Tour's mountains.

TOULOUSE, France (VN) — Perhaps the biggest surprise of this Tour de France isn’t that Chris Froome is wearing the yellow jersey, but that Geraint Thomas is climbing with the favorites deep into the mountains.

The 29-year-old Welsh rider has been Sky’s last man in three stages across the Pyrénées, and rolls out of a trio major mountain stages fifth overall, 4:03 back.

Thomas is taking it all in stride.

“I am feeling good, and morale and confidence is high. I am just buzzing off that,” Thomas told reporters. “Everyone is buzzing off Froome. He’s confident; he’s strong. We’re hearing that on the radio. It gives everyone a boost.”

In three decisive stages across the Pyrénées, Sky is making its presence known in the peloton. The team lines up over the climbs, with riders such as Luke Rowe, Nicolas Roche, and even Ian Stannard taking early pulls. Richie Porte and Thomas have been the final riders pacing Froome up the final climbs.

In Tuesday’s first summit finale, Froome surged away to victory, but Thomas was able to come home sixth, two minutes behind Froome, and one minute behind second-place Porte. There were no major shakeups Wednesday, and Thomas once again was solid over the Col du Tourmalet and in the final up Cauterets. The story repeated itself up the brutal steeps of Plateau de Beille on Thursday, but Porte peeled off with about 5km to go when Nairo Quintana (Movistar) took a dig, leaving Thomas to pace Froome to the line.

Froome’s acceleration, moments later, drew out of Quintana and actually dropped Thomas, but Froome eased up against a steady headwind, and the leading nine trailed in behind Alejandro Valverde (Movistar), with Thomas staying a surprising fifth overall.

“I see myself up there on GC. I’m just buzzing off of it. I could have a bad day at any moment, so I am not taking it for granted. We’re just digging in for Froomey,” Thomas said. “We’re trying to keep Froomey’s advantage intact.”

It’s important to point out the real heavy lifting so far in the Pyrénées has come from Porte, not Thomas. The scrappy Tasmanian has been the Sky rider leading the pace up the meat of the final climbs, chasing down the moves, with Froome and Thomas tucked in behind.

The team is saving Thomas, and protecting his strong GC position as an added weapon in the inevitable tactical drama that’s bound to unfold in the closing 10 days of the Tour. In short, to get to Froome, his rivals will have to go through Thomas.

Some are wondering how Thomas, who races well across the pavé of Northern Europe, including victory this year at E3 Harelbeke, could be climbing so well. Thomas said he’s been on a steady progression since leaving track racing behind for good after taking gold on the boards at the London Olympic Games in 2012.

“Since leaving the track, I certainly feel like I am improving in the hills; 2013 was a bit of a year out, with the pelvis [injury], but it’s nice to see a progression. Hopefully I can continue,” Thomas said. “One of the week-long stage races, I want to win one of them. Three weeks? That’s a different kettle of fish. We’ll see just how it goes.”

Some draw comparisons between Thomas and Bradley Wiggins, another track racer who packed the power, lost weight, and became a grand tour contender. Wiggins, of course, won the 2012 Tour. Could Thomas go as a far? He’s had steady progression in stage racing, winning the Volta ao Algarve this year and finishing second at the Tour de Suisse ahead of the Tour.

“Through the classics, I put on a bit of weight, in the cold, and you do one race a week, you need fuel during the race. I’ve lost a bit weight coming here,” he said. “I am feeling really good. Morale is really high. The confidence is high, especially after [Tour de] Suisse, it all adds up.”

Thomas’s and Team Sky’s strong Tour has inevitably drawn comparisons to the infamous “blue train” of the U.S. Postal Service team, and classics rider George Hincapie, who often pulled deep into the mountains, and even won a stage high in the Pyrénées. Those results were erased when Hincapie admitted to doping as part of the U.S. Anti-Doping Agency’s case that brought down former seven-time champ Lance Armstrong.

“I am happy with how I am going, how the team is working,” Thomas said. “I know I have a clear conscience, and that’s all that matters.”