The bug had been playing havoc with his preparations for the Tour de France, which rides out next Saturday for three weeks of torture. Add to this the fact that his team, GAN, who face extinction if a new sponsor is not found by 1 September, had been struggling, too, recently losing their world No 1 ranking, and it would have been understandable if he had elected to remain incommunicado. But Britain's most successful cyclist is not that kind of man.
"Yesterday was a catastrophic experience, but you get to the point where you're full up - you think, `Come on, I'm already on the floor, it doesn't matter if another three, five, 10 things go wrong'."
Indeed, apart from the medical problems, he had dropped his water bottles, leaving himself with nothing to drink in 30C temperatures, been forced to change bikes when his gears packed up, and then had more gear trouble on the replacement bike as the finish was nearly in sight. The day we met there had been no catastrophes, but he had still slipped back by nearly a minute and a half.
In 1994, he speculated that in three years' time he would be physically capable of winning the Tour de France, but as we sat in the dining room of his team's hotel in the mountain-ringed town of Digne-les-Bains, the capital of Haute Provence, with the Tour imminent, he was understandably more circumspect.
"If somebody says something once then that becomes the absolute truth. The Tour de France is the biggest race in the world, so I'm trying to be at my very best. But there are 200 guys trying to do the same thing."
Last year, his third time out, he finished 39th, processing the Champs- Elysees for the first time. In 1995 he had lasted 92 seconds, crashing in the rain on the Prologue time trial and breaking his collar-bone and ankle. On his debut in 1994, when he was only trying the Tour on for size, he took the yellow jersey on the first day and pulled out honourably on the 11th. At the age of 28 - he is 29 in August - what's required for him to fulfil his potential?
"I need to be consistent daily. That's the big challenge. And that's not easy."
His preparations have been thorough. Like many of his colleagues he uses the SRM system, an on-board computer - below the saddle, in fact - which records speed, pedal revs, his heart rate and his power output. In the first few races of the season he is monitored constantly, providing him and his coach, Peter Keen, with information that enables them to perfect his training programme.
As the season progresses, though, the highest-grade information comes from simply listening to his body. "Now, it's a case of `you can do it or you can't'. It's all on feel."
In fact, though any sporting activity requires a baseline of physical fitness, in the end, isn't winning all in the head?
"Yeah, absolutely. The first ingredient you have to have is legs. And after that you have to know how to use them. If you use your team early, chasing small breakaways and so on, just having the strongest legs won't be enough. If you don't have the head you waste the legs."
David Hemery has famously spoken of having run the Olympic 400 metres hurdles final in his head hundreds of times beforehand. Does Boardman do anything similar?
"For something as intense as a Prologue, yes. I have a terrible memory generally, but I know each bend and I can picture how I'm going to ride it. I've climbed all the mountains on this year's Tour and made notes on each climb - where it's hard, where there's a false climb. I've done seven days, nearly a thousand kilometres - not necessarily all of every stage, but all the mountains."
Though he comes across as eminently well-balanced, it's clear that Boardman has the same kind of "tunnel vision" that Linford Christie has spoken of. In fact, he does not regard himself as the sanest person around.
"I'm fanatical about trying to be the best. I think you'll find that other riders may be mentally more healthy than me. I'm very intense about what I do, it absorbs all my thinking time, and my family pay the price."
For many riders, the only way forward is to head for the Continent, eke out a living as an amateur and hope to get spotted. Boardman turned pro relatively late, by which time he was already a family man, and it grieves him greatly to leave his wife Sally-Anne and four children on the Wirral.
"For months of the year I spend two days at home, then go away for nine days, two days at home, go away for 10 days. The children are growing up and I'm not there. They don't wait for me to come home to grow up."
And even when he is there, he is still a monomaniac. "I'm only physically there - mentally I'm somewhere else. Luckily I have a very good wife who accepts the way I am, and I make an effort to do things with the kids, spend some time with my wife - and I'm better at it now.
"My son Edward is dyslexic, though it's not a massive problem these days. He goes to a fantastic school 800 metres away, eight or nine children in each class, like a big family. And he gets special help. It's good to be able to afford to do things like that." And what if his his kids wanted to go into cycling? He smiles wryly and leaves a measured pause. "I would advise them to do something else."
With a distribution company importing Adidas products, and other investments in the pipeline, Boardman is preparing for the day when he will be doing something else.
"Hopefully by the time I finish my career I'll have, say, five different interests. That's the plan. It seems to be going OK at the moment."
And how long does he give himself in the sport?
"Four more years. Five more absolute tops. I prefer it like that - I've got four years and I have to make it work. I know when it stops and I can be intense because I know when the end is. I've always been an extremist - I have to do everything 110 per cent. And it probably means that my career will be shorter than other people's."
Perhaps the route Boardman took into professional cycling gives him a perspective not shared by many of his fellow pros. After his success in the Olympics and the world championships and with the world hour record under his belt, he effectively entered the ranks as middle management, without the need to put in the miles as a domestique, the fetcher and carrier, the man who gives his all for his team leader. But it was still a shock to the system.
"In the first couple of months I didn't think I'd make it. But I had no choice. I never really wanted to turn pro because I could see all the 200km races, 90 to 110 race days every year - it's a very hard life and it didn't appeal to me. But as an amateur I'd got to the stage where I couldn't do a lot more. I could stay where I was and wait to go backwards, or turn professional and try and go forwards. When that became clear to me I didn't really have a choice. I tried to think of it as a challenge and not a problem."
British sporting emigres are notorious for their inability to embrace Continental culture, but Boardman, who took French lessons as soon as he'd decided to turn pro, had no such problems.
"The culture I like. They're a lot more sociable here, they spend less time watching television, more time talking. Sometimes that can be irritating, when it takes two hours to have a meal and you just want to go bed. But the food's better, the quality of life's better, there are less cars. And they have more respect for what I do for a living. In fact I can't think of a reason not to live in France, but home is home for all its faults."
So does he feel he's the proverbial prophet without honour in Britain?
"I think it's a shame, but it's not something I've really thought about. Wouldn't it be great if all this" - he spreads his hands wide to indicate the whole carnival that exists around cycling across the Channel - "existed in England? Perhaps that's why les etrangers do well when they come to Europe - they've really had to make sacrifices to be here. Most riders have to go to an amateur club, live in apartment on their own, not speaking the language, and that's hard."
Once the small matter of the Tour is over, he has to sort out his future, and if GAN is not replaced as principal sponsor, he will be on his way, with the Spanish glamour team, ONCE, among the favourites to snap him up.
If he does move, it will probably not be as team leader. Would he mind that?
"No. I often think I'm in this position more through circumstances than because I'm right for it. It was great for me when Greg LeMond was here, and it would be nice sometimes to have someone to take a bit of the pressure."
LeMond, whose premature retirement in 1994 accelerated Boardman's development, was a big influence on him, as is Roger Legeay, GAN's team director. But as a youngster was he inspired by anyone?
"I never had heroes. I just aspired to be where the best were. That might sound arrogant. I've already done some things - world champion, Olympic champion - it's already been OK - but there's still some things I think I'm capable of. I'm not finished yet. You don't know where the top is till you start on the descent."
And so he wrapped things up and went back upstairs to recharge. It was rest he patently needed, as became clear the next morning. The Dauphine Libere pulled out of Digne on its way to Briancon, over two of the toughest climbs in France, the Col de Vars and the infamous Col d'Izoard. But Boardman had blown up before either of these two massive obstacles.
As I sped past the feeding station at Barcelonette in one of the team cars, I saw him by the side of the road, pedalling in the opposite direction to be picked up, forehead and eyes screwed up in discomfort. Though a television camera was stuck three inches from his face, he accepted it with as much good grace as anyone who has been to hell and has not yet come back can muster.
I met him by chance outside his team hotel in Briancon later, on his way to pick up a helicopter back to Lyons and then back to the Wirral and the family. "How do you feel?" I asked, superfluously. He took a long, deep breath. "Shite," he said.
The impression I had taken away with me the previous day was of a man driven but incredibly decent. Later, I found out what a good bloke he is. He had had an arrangement to be photographed after the stage to Briancon in a Rochester Classic T-shirt to publicise the race over here in August, and I assumed that his premature exit would have put paid to that. However, when the photographer due to snap him in his T-shirt, Graham Watson, approached him at the finish and apologised for taking a standard post-race picture of him looking unwell, the first thing he said was, "That's OK. Now what about the Rochester picture?" The man of the road is still the man in the street.