Yet, his ride to victory was faultless, almost inevitable, right from the moment when Dave Brailsford, in the midst of the investigation of Chris Froome’s elevated salbutamol level, asked him to prepare for the Tour as Team Sky’s leader.
Throughout this season, Thomas batted aside questions about Froome and other issues affecting his team, repeating that he was in his own “bubble”. His progress towards the Tour was relatively serene, the only significant setback a below-par performance in the mountain time trial at the Tour de Romandie. Subsequently, the Welshman has hardly made a wrong move…
Critérium du Dauphiné prologue: The 6km out-and-back course from the centre of Valence was fast, but relatively straightforward. Chasing the best time set by team-mate Michal Kwiatkowski, Thomas was steaming towards victory until he reached the 180° turn back towards the city.
Coming into it too fast, his bike slipped away from him and Thomas slid across the road and into wire fencing. It could have been the end of his Tour hopes, but he escaped with road rash and a slight dent to his Dauphiné hopes.
Dauphiné stage to La Rosière: Wearing the yellow-and-blue leader’s jersey as the race headed to its toughest summit finish, Thomas employed the tactic that would serve him so well at the Tour.
Harried by Romain Bardet and Dan Martin, Thomas responded to attacks but held himself in check until he was inside the final kilometre. His surge added a few seconds and some bonus time to the cushion Sky’s success in the team time trial had already provided. Overall victory was confirmed the next day.
The Tour’s opening week: While all of his major rivals, apart from Primož Roglič, lost significant time due to crashes, punctures or other technical mishap, Thomas breezed through the first nine stages.
As Roglič lost significant ground in the TTT, where Sky were right on the heels of victors BMC, Thomas went into the first rest day as the best placed of the overall contenders.
Stage 12 to Alpe d’Huez: Thomas confessed at the end of the race that this stage was critical to his success.
After a stalemate between the favourites on the first stage in the Alps to Le Grand-Bornand, Thomas took the yellow jersey at La Rosière, employing the same tactic that had served him so well at the Dauphiné, controlling attacks until the final few hundred metres, before bursting away to climb the stage win.
The attack came late because Thomas wanted to preserve his resources for the 5,000 metres of vertical gain that would take the Tour to Alpe d’Huez. Reaching the summit with the other contenders confirmed that Thomas was a genuine challenger for the title.
The beautifully-completed manoeuvre coming out of the final turn that enabled him to sprint clear to secure back-to-back summit victories was as a sign of a rider at the very top of his form.
Stage 17 to the Col du Portet: Untroubled at the tricky climb up to Mende on stage 14, this 65km “sprint” to the Tour’s highest point was the Pyrenean equivalent of the day to Alpe d’Huez.
Sprinting clear of Tom Dumoulin and Primož Roglič for third place and four more seconds was significant, but more so was the time he gained on team-mate Chris Froome.
Now almost two minutes clear of the defending champion, who was still second on GC, Thomas put an end to the constant questions about who was riding for who at Team Sky. Now everyone, including Froome, was riding for Thomas.
Stage 19 to Laruns: There was still some talk among Thomas’s rivals that the Welshman might yet collapse, reminders that he had never previously finished higher than 15th in any Grand Tour. These thoughts may have buoyed up the other favourites, but they were completely without foundation.
Once Thomas had completed the high-speed drop off the Col d’Aubisque, the Tour was won. With a buffer of two minutes going into the final time trial, Thomas had relegated rivals to a battle for the lower steps on the Tour podium.
The yellow jersey was his.