Geraint Thomas expects his next three days to be tougher than competing in the Tour de France as he commits to spending 36 hours on a turbo trainer to raise money for the NHS.

The 2018 Tour winner wants to replicate the shifts of an NHS worker as he embarks on three 12-hour stints on the bike with the goal of raising £100,000 to help the fight against the coronavirus.

Thomas has no targets in terms of speed or distance, and no mountains standing in his way, but the Team Ineos rider expects this to be up there with the greatest challenges he has faced – because that is how he designed it.

“I think it’s going to be a lot harder than a Tour stage,” Thomas said. “Just because you’re not racing. I’m just going to be pedalling away in my garage sat in Cardiff. I haven’t got that competitive edge to keep me racing.

“Timewise it’s a lot more – three days, 36 hours, it’s close to eight or nine stages of the Tour. Obviously it’s a lot slower but physically it will be tough and mentally it’s even harder.

“But that’s what I wanted, a challenge.”

With 100-mile rides all part of the day job, Thomas knew he had to come up with something more extreme to raise some serious money, but was eager to do his bit for the NHS in the midst of the pandemic.

“The NHS means a lot to everyone,” said Thomas, who has already raised more than £27,000 via Gofundme without turning a pedal. “We all know someone who works for them in some shape or form and everyone understands the commitment they are making.”

For Thomas the connections are close. His best man is a GP, while his mum Hilary has come out of retirement for a third time to offer her services at the Velindre Cancer Centre in Whitchurch, Cardiff.

“She has retired three times, but she keeps going back again,” he said. “When this pandemic came along, she rang them up and said, ‘Do you want me to come back?’ so she is doing two days a week.”

Thomas has never previously spent longer than eight-and-a-half hours in the saddle – a lap of Majorca during the Ineos training camp in December – and knows he will need plenty of distractions while on a static bike.

He will be logged in on Zwift, the virtual platform that allows others to join in for stints of his ride, while Wales’ record try scorer Shane Williams, 43, has signed up to join Thomas throughout all three days.

“He’s done Ironman stuff before and he was well into it,” Thomas said of Williams. “I’m trying to bully George North into doing it but he’s not having any of it.”

Otherwise Thomas is planning to chat to fans via live streams of his effort on Instagram and Facebook, while catching up on F1 series Formula One: Drive To Survive on Netflix, having decided Tiger King is “a bit weird”.

Thirty-six hours on a turbo trainer is far removed from the Tour itself, with the fate of the race this summer unknown.

With speculation the Tour could now start in August, Thomas said he will continue to work towards competing.

“That’s how I’m treating it, that it’s going to happen,” he said. “I am hoping and praying that it is going to go on, we will all be there and all this will be done and dusted.

“It might not be back to completely normal but at least everyone can sort of move on.

“I would be willing to race whenever really to get the races in. Because that’s what we want to do, we are bike racers, that’s what we do it for.”