Thomas has not yet decided what that new challenge will be, but he will have plenty of choice.
There is a chance he could stay with Ineos Grenadiers in a new capacity, while there will be no shortage of offers to work in the media.
“Having options is always good,” Thomas says. “I need a purpose. Since I was about 17 or 18, I’ve always been working towards a goal.
“To not be working towards anything would be nice for maybe a month, then I’ll just go crazy, so I’ll definitely have to have some goals.
“I want to do an Ironman. I only run two or three times a year, so that’s something that needs a bit of work! It’s about challenging myself in different ways.”
A future as a triathlete can wait. Once he retires, what Thomas is most looking forward to is spending more time with family and friends, particularly his wife Sara and five-year-old son Macs.
“That’s the main thing, just being around more and not missing events – birthdays, weddings, parties or whatever,” he adds. “I’m looking forward to that side of things.”
Retirement is also bound to bring with it myriad offers to appear on reality TV programmes, although Thomas has been warned off Strictly Come Dancing.
“I reckon the fitness would be the only thing I’ve got. I wouldn’t back myself. Although my parents-in-law tell me ‘please don’t do it, you’ll make a fool of yourself’ and that makes me want to do it,” he laughs.
“That would be the biggest challenge of my life for sure. Maybe I’ve got the hips for it.”
Having completed the 2013 Tour de France despite breaking his pelvis during the opening stage of the three-week race, Thomas has proved that he is ready to test that particular area of his anatomy.
In fact, there are few parts of Thomas’ body that have not been bloodied or bruised at some point over the course of his career, and his physical fortitude has earned him the respect of his peers as well as cycling followers around the world.
Once he has navigated his final Tour de France and one last summer on the road, Thomas plans to bring the curtain down on his career at the Tour of Britain in September.
The route has not yet been finalised but the closing stage could be held in Cardiff, the city where Thomas was born and bred and where he will return to live after retiring.
“It would be epic if that happens. I haven’t really thought about it much, but when I do start thinking about it, it’s going to be emotional. Maybe I’ll shed a tear or two,” Thomas says.
“It would be some way to finish, whether it’s Cardiff or wherever, the Tour of Britain as the final race. It’s full circle, isn’t it? Finishing my career back home.”