For the next three weeks these pages will be packed with legions of extraordinary athletes, but be assured of this: there are few you will find as arousing as Rebecca Romero. And that is not because she looks good naked on a bike.

Even for a professional athlete, where character traits such as self-belief, drive, selfishness (not intended as a negative) and courage are necessities on the check-list, Romero stands out. Even fully clothed.

Check out her first date with cycling. She went to the Manchester velodrome for an interview with Dan Hunt, the coach, in early 2006, having retired, aged 26, from rowing in which she was an Olympic silver medal-winner with a better than decent chance of stepping up to gold in Beijing. It takes an unusual kind of personality to walk away from a gold medal, but that is not the point.

She was in Manchester to talk about transferring to cycling. No one had previously gone from rowing to cycling with much success; there was something beautifully preposterous even in the idea. Yet after only two hours, Hunt was convinced that he wanted to give the experiment a go - and he hadn't even put her on a bike.

“We did do the physiological testing afterwards,” Hunt recalls. “But she had come from elite rowing, so the results that came out were what we expected. What struck me was her mindset: very forthright, driven by a need to succeed. Everyone wants to win, but there is a class of athlete who needs it, their emotional input is higher. Winning is everything. In that meeting, I thought: 'Wow! This is one driven girl!' That was the clincher.”

But check out another personality feature that Hunt and others discovered very soon afterwards, a trait that made them all stand back in amazement. Indeed, it was a trait that was probably definitive in ensuring that this outsider could find the back door into a team of world champions and earn immediate respect: in training, she had an extraordinary appetite for pushing herself to extremes of pain.

Hunt said that it was “worrying”, but only worrying as in “astonishing”. Dave Brailsford, the performance director of British Cycling, just chuckled at the subject and struggled to complete the sentence: “In terms of being able to hurt yourself ... boy oh boy!”

Interestingly, Romero herself disagrees. “I always think I'm not tough enough, not hard enough, not disciplined enough,” she said. “I'm aware that I have to be better, that others will be pushing themselves harder and tolerating more. I know my weaknesses, generally it's the drive and commitment every day, the physical effort you have to push yourself through. I am generally a lazy person.”

Hmmm. In which case you wonder how good she would be if she pulled out all the stops. For the moment, though, she is good enough: good enough to be a double world champion, good enough to be going to Beijing as favourite for the women's individual pursuit. No one - certainly not Hunt - had dared to consider that she could come so far so fast.

What is clear is that her gifts go beyond the biomechanics of an elite rower. Britain's cyclists do much of their training by riding on a running treadmill. It usually takes a rider two or three sessions to master this, but Romero did it in under a minute and was riding no-hands after 30.

One of the challenges in the individual pursuit is learning to hold a hard but controlled pace. Hunt hooked Romero up to an iPod that would beep whenever she was supposed to be at the half-lap mark and soon her pace judgment was spot-on. Yet the pursuit, as Brailsford explained, was not an obvious choice. “It isn't a flat-out race,” he said. “It's a controlled effort, right on the very physical limits. It's like slowly squeezing an orange and controlling the squeeze so you keep the juice just to the end. For a non-cyclist, that kind of control for four minutes is a real challenge.”

But again, it is hard to master this technique or pace control without having intense mental fortitude. The desire to race an individual discipline is itself an expression of her personality. No one, least of all Romero, denies that one of the many frustrations she felt in rowing was the feeling of being cooped up in a crew and not able to live or die according to her own successes or failures.

But now she has separated herself from the pack, so much so that she has been chosen to endorse Powerade, the sports drink, and their “InnerGear” concept in her full glory. The image highlights the strength, fitness and power that is put into her training. Call it naked ambition if you like, but check out also the picture and the facial expression of sheer determination.

What is interesting is that, while this extreme personality has been driving her to another Olympics, she has not really had time to stop and consider what sort of personality that is. Connoisseurs of naked cyclists - come on, we know you are out there - will be aware that she is not even the first to cut this pose, that Victoria Pendleton is half a year ahead of her. But Romero had not even considered that she might be on Pendleton's patch.

“I honestly hadn't thought: ‘that's the pose that Vicky did'. I'm not trying to do the same as her,” she said. “We are very different people. She's in a slightly different light.”

Which raises the question: in what sort of light do you see yourself? “That's a tough question because until recently I've never had to think about it,” she said. “I've always been an athlete in the background. It's only recently I've been asked: ‘Who is Rebecca Romero? What do you want to be seen as?'”

And now? “If I have to have an image, for me it's that I am as I am: completely honest. A lot of British athletes go on about how they're happy if they've done their best performance, but I always go on about the fact that I want to win gold and that I'm not happy unless I do. That is me being honest.” She knows no other way.

Team GB competitors at the Olympics will be supplied with Powerade to support training and performance