Thomas, who won Olympic gold medals in 2008 and 2012 as well as the Tour in 2018, has previously trained with Cameron Wurf, a former pro cyclist turned triathlete.
And, speaking during an interview at Nytro, a triathlon company in California, he says he hopes to try an Ironman event, which consists of a 2.4-mile swim, followed by a 112-mile bike ride and a 26.22-mile marathon.
“I used to swim as a kid and did a few triathlons,” he said.
When I retire from professional cycling I definitely want to do an Ironman, or maybe even a few. I'll do the Wales one first, I've heard the bike course is quite hard so that could play in my favour.
The Team Ineos rider, who turns 34 in May, also suggests he plans to continue cycling for ‘three or four years’.
"I think I'll need something when I stop, because if I stop in three or four years... this is my 14th year now, so I could end up doing 18 years as a pro.
“Then before that I did two years as an amateur, and as a junior, cycling is your life then as well, so it's 20-odd years where that's all you do and that's all you think about, and you've always got a goal within two or three months
“To stop and not have anything would be tough, so why not an Ironman?”