The climb up the feared Col du Galibier was the hardest day for Thomas during his Tour ride in 2005 - it awaits once more on 19 July
What is it about Geoff Thomas, France and audacious efforts?
To football fans of my generation, Thomas is probably most readily remembered for his attempt to chip French goalkeeper Gilles Rousset from 30 yards out when through on goal in 1992.
It could have booked his place in England's side for that year's European Championship, it could have been the passport to a big-money move, it could have been one of the most talked-about international goals of recent vintage. Instead, it went off for a throw-in.
When I asked Thomas recently what he was thinking prior to attempting his unlikely lob - a question I had shouted at the screen 15 years ago - he smiled and said: "What was I thinking?
"I'm not sure but I suppose I was hoping to score a great goal for my country at Wembley. It would have been the type of goal people would have talked about for months.
"I used to hate people going on about it the whole time. (David) Baddiel and (Frank) Skinner gave me terrible stick for it on television, I think it affected my form.
"But I love it now. If that's what people remember about me, so be it. The way I look at it is that I was in the position to take that shot, playing for my country at Wembley.
"The funny thing is I had a few one-on-ones with keepers before that and afterwards and I always slotted them."
From anybody else that would not have sounded "funny" at all - poignant, sad, bitter even, but not funny.
Because the fraction of a second before he connected with the ball that night was the high-water mark of what had until then been a pretty life-affirming footballer's fable.
From quitting his better-paid job as an electrician at 18 so he could chase his football dream, to leading Crystal Palace to a 4-3 FA Cup semi-final victory over Liverpool (a team that had beaten them 9-0 earlier that season), to forcing his way into the England team, Thomas's career was not short of fairy-tale moments.
Thomas during last year's charity replay of the 1990 FA Cup final
Then came that "chip". The tough-tackling midfielder did not play for England again, despite never being on the losing side. The following season was a struggle. His first marriage broke up, Palace were relegated and his father died of cancer.
But when Thomas said he was able to see the funny side of this possibly pivotal moment in his life I believed him. I believed him because his father's death was not the last time Thomas was touched by cancer.
In June 2003, a year after his playing career finished, Thomas was diagnosed with chronic myeloid leukaemia.
I had lost track of Thomas's post-chip exploits - an injury-jinxed decade after Palace's relegation saw him play for Wolves, Forest, Barnsley, Notts County and Crewe - but I remember reading the news and thinking how sad that was for a player I remembered as a genuine leader and under-rated footballer.
Eighteen months later and Thomas's name was back on the national media's radar and once again it was a bold attempt with a French flavour. But the opponent was not a Frenchman, it was the entire country, its snow-capped heights in particular. And his weapon was a bike not his boot.
This time, however, fortune did favour the brave - and there can be few braver than a man who attempts to ride the route of the Tour de France six months after completing a year and a half of life-threatening treatment for leukaemia.
In some ways I wish I had discovered cycling earlier - I love it
And now, two years on, the 42-year-old Thomas is going to do it all over again - 21 days in the saddle in the middle of the French summer, covering 3,550 kilometres and climbing 21 seriously steep summits.
Not bad for somebody who was given only a 30% chance of living beyond 41 just four years ago.
His first crack at the Tour, which was inspired by fellow cancer survivor Lance Armstrong's yellow jersey exploits, raised over £170,000 for research into leukaemia and other blood cancers.
When Thomas told his consultant he was thinking about riding the Tour for charity, his doctor replied: "Geoff, normally at this stage of their recovery people ask me if they can go swimming."
The doctor had a point. Thomas's legs, by his own admission, were "just bones", and he did not even own a bike.
But showing the kind of determination that helped him fight back from the 27 operations he had during his football career, Thomas got himself ready for the Grande Boucle inside six months.
"When I did the ride in 2005 I wanted to prove to myself that my life wasn't going to be controlled by leukaemia," explained Thomas, whose hero Armstrong won a record seventh Tour de France in a row that year.
Thomas was a regular in England's midfield in the run-up to Euro 92
"It was a payback for all those people that helped me get through the treatment but it was also a personal thing.
"But this time my focus has changed. I have a lot more knowledge about cancer and I really want to help.
"I think people that have experienced cancer know it's a life-changing thing. It stops you, it drags you down, but it also makes you realise what is really important."
In 2005, having reached the Tour's traditional finish on the Champs-Elysées, the really important thing for Thomas was to get off the bike.
"After the last ride I was like Steve Redgrave when he quit rowing," he said.
"I told everybody to shoot me if they saw me near a bike. I didn't go near one for about six months."
But a strange thing had happened to him on those long climbs in the Alps and Pyrenees, he became a cyclist.
"The truth is I became very attached to my bike," Thomas admitted.
"In some ways I wish I had discovered cycling earlier. I love it. I would like to organise races in the future.
Armstrong must be a driven guy to put so much time into his foundation - it's awe-inspiring really
"I love the team ethic you find in football but you get that in cycling too. And the thing I really like is that when you come to the bottom of a big climb it's all about you."
So another French revolution was always on the cards for Thomas, it was just a question of when. He had planned to do it again in his fifth year of remission but the Tour's start in London this year was an open goal he had no intention of missing.
And having spent the last few months setting up the Geoff Thomas Foundation - another Armstrong-inspired brainwave - he is ready to launch himself into a heroic bout of fund-raising.
"I want to reach people that haven't been touched by cancer too," said Thomas, who will be joined on his ride by five other cancer survivors.
"I want them to know that there is something out there that can help them if they are ever unlucky enough to experience it.
"It's like the Lance Armstrong Foundation. You don't think of illness when you think of that, you think of something more fresh and alive."
The foundation's aims are to raise money specifically for the development and delivery of new treatments to patients with blood cancers. Five centres have been identified - Birmingham, London, Manchester, Nottingham and Oxford - and the immediate goal is to pay for a clinical trial nurse in each of them.
At £30,000 each, this kind of expertise does not come cheap. But as Thomas has discovered, beating cancer is largely a numbers game.
Thomas was honoured at the 2005 Sports Personality of the Year show
"The technology is catching up with cancer but it takes a lot of money and expertise," said Thomas, who starts his 2007 Tour with a prologue in Hyde Park on Monday 9 July.
"The sad thing is that in terms of getting the latest treatments to the patients, we are trailing other countries at the moment. We have fallen into the second tier.
"There are people who got into trials five years ago for new drugs that would not be here now otherwise. There are so many more that could be helped this way.
"Getting new drugs on the market takes a long time. It's all about finance. Money makes everything work quicker."
Thomas is realistic (and modest) enough to admit that he lacks the tin-rattling muscle of a Sir Ian Botham - "I can't just click my fingers and get Marks and Spencer on board" - but he knows from personal experience that he can make a difference. And the fact that he can is imperative enough for him to try to do so.
It is perhaps fitting that a footballer who was most famous for fluffing a shot should become famous as an ex-footballer for making the most of his second shot at life.