The Briton won team pursuit gold on the track at London 2012 before setting his sights on the road and, in the last few years he has been exploring his potential as a stage racer and possible Grand Tour contender with Team Sky.
After winning the Volta ao Algarve in 2015, he won his first WorldTour stage race at Paris-Nice in 2016 and then won the Tour of the Alps last year. E3 Harelbeke and a stage of the Tour de France also rank among his achievements but he insisted the Dauphiné tops the lot.
"It's the biggest win of my career," he said in Saint-Gervais after pulling on the yellow jersey for the final time.
"It's kind of surreal. It hasn't sunk in yet because I never let myself believe it. I was always thinking about the next day or the next climb but maybe tonight it will start to sink in.
"It's a massive race. I never even dreamt of winning this when I was turning pro with Barloworld and racing on the track. It's just a different life. At that time I was a lot heavier, and it was a completely different focus. Since London 2012, I really focused on the road and improving all the time and this is just an incredible victory for me."
As Thomas admitted, it can sound clichéd when a rider dedicates a victory to his teammates. Thomas produced what was perhaps his greatest climbing performance in the second half of the race, but his win was firstly built on Team Sky's stage 3 team time trial victory, and the subsequent efforts from his teammates – notably the young Tao Geoghegan Hart – to control the race in the face of an onslaught from Romain Bardet's AG2R La Mondiale squad.
"They have confidence in me and I've got loads of confidence in them. They really looked after me, especially today with the two punctures – the guys were really calm and kept me calm. I owe them a lot," Thomas said.
"This victory is just as much theirs as it mine and I know everyone always says that but I've been on that side of things and I know how hard it is and how important it is."
Tour de France and future contract
It's difficult to talk about the Critérium du Dauphiné without the Tour de France creeping into the conversation. Chris Froome would appear to be, on paper at least, to be Team Sky's leader, having won the past three editions of the Tour. However, Thomas, having finished 15th in 2015 and 2016, is angling for a true co-leadership role.
With some degree of uncertainty hanging over Froome, who already has a Giro d'Italia in the legs this season and could even be banned from racing over his salbutamol case, Thomas' Dauphiné victory has sent out a strong message.
"It's obviously a big boost to morale. For sure it's a massive boost to the confidence," he said. "We'll see how it pans out at the Tour. As I've said, in that first week anything can happen."
Thomas will stay in France to recon some of the key stages of the Tour de France with his team before heading back to Monaco for a couple of days' rest. He'll then go on a short training camp before travelling to the Vendée at the start of July for the start of the Tour.
"I'm just going to enjoy the next few days and rest up to get to the Tour in the best shape possible," he said.
But there's also has the small matter of his future to settle. Having toyed with the idea of leaving Team Sky for a greater leadership role in the past couple of years, Thomas is out of contract again and considering a switch of teams for 2019.
He told Cyclingnews at the start of the week that Team Sky were determined to keep him but that he was open to offers from other teams, and that he wanted to decide his future, whichever way, before the Tour de France. [UCI rules allow riders to renew contracts before August 1, but transfers are prohibited before that date. -Ed.]
"I can see it being another team, but at the same time I'm super happy here," he said in his press conference.
"It works really well for me to be in my best shape possible here, I'm used to it and I know how it all works. But there are a lot of other good teams around. I'm happy here, but hopefully, it will all be sorted in the next couple of weeks."
Thomas suggested that if he is to re-sign with Team Sky, having a chance to lead the team at the Tour de France would be one of the conditions.
"It's one of the things I've been speaking to Dave [Brailsford] about," Thomas confirmed.
"As long as I'm good I'll get the chance. You have to have the legs to lead the team, first and foremost, and I feel confident that if I show that in training and racing I'll get the chance to lead the team. This year I've done the programme I wanted and led at all the races, so I'm certainly not unhappy."
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