In a quiet corner of the velodrome that bears his name, Sir Chris Hoy is reflecting on a journey that has been as filled with emotion as any that he experienced in his medal-winning years on the bike.

On an October afternoon last year life changed forever for the six-time Olympic champion when his son Callum arrived into the world 11 weeks premature.

For Sir Chris and his wife Sarra a tumultuous period followed as Callum spent his early weeks in an incubator hooked up to an array of tubes and wires at a neonatal unit near their Manchester home.

Until that point, says Sir Chris, there had been no problems in the pregnancy. "Sarra went in [to hospital] feeling a bit unwell, she had a few checks and they said: 'Right, the baby has got to come out now.' It was completely out of the blue," he recalls.

It was an anxious time but Callum soon began displaying echoes of the same tenacious fighting spirit that made his father a world beater on the global cycling stage.

Their son was allowed home in early December after eight weeks in hospital and has since gone from strength to strength. "He is just over three kilos - almost 7lbs," says Sir Chris. "He was 2.2lb at his lightest, so he's more than three times heavier now than when he was born.

"It's nice because we are starting to see a difference. Callum is beginning to smile, he can focus on you, follow your hand; all the little benchmarks. He certainly has a set of lungs on him and doesn't sit still - he's moving all the time.

"People do say he looks like me, but I think they are just saying that to be nice. He has got slightly darker eyes; they are more like Sarra's than mine."

For Sir Chris, 38, the memories of those early weeks are understandably still palpably raw, but he is able to draw on the positives.

"You didn't think too far ahead - it was day-to-day," he says. "We were incredibly lucky. Callum was quite unusual in that, apart from one minor setback, he had a really consistent, steady improvement in gaining weight. It could have been a hell of a lot worse. You always count your blessings."

When December 27 rolled around - Callum's original due date - the couple made sure they marked his remarkable progress. "We had a bottle of Champagne for Callum, it was a good excuse to open a wee bottle of bubbly after Christmas," says Sir Chris.

Callum gets his middle names from his two grandfathers - David and Robert - but with his arrival coming so unexpectedly choosing a first name led to some hurried, head-scratching moments.

"There were so many things we had been planning to do in that period, even down to his name," says Sir Chris. "We hadn't thought of one because we didn't know if we were going to have a boy or a girl. We had to plan a name last minute and we didn't even come up with a girl's name in the end. Not because we thought we were going to have a boy, but because we couldn't decide on one.

"It's funny because when you start to think about naming your child, whenever you come up with a name, one of you knows someone and it's: 'Oh no, you can't call them that because so-and-so is a pain in the backside' or 'that's the name of my ex-boyfriend.' It's trickier than you think."

With Callum now almost four months old, Sir Chris is settling into the rhythm of family life. "The lack of sleep, as everyone tells you, is the biggest change," he says. "I can't complain because Sarra has been doing 95% of the night stuff. There have been some nights she's had less than two hours sleep and then been shattered in the morning.

"She loves being a mum and is doing so well in dealing with the lack of sleep. The slight complications of having a premature baby does add a dimension to the details of what you have to do as a parent, but it doesn't matter how many books you read or what advice people give, you have just got to learn things yourself. It's gone really well so far."

Edinburgh-born Sir Chris has quickly cottoned on to the perks of fatherhood. "I was driving round the supermarket car park with Callum in the back, it was raining and I was thinking I would have to make a dash in with him when I realised: 'Wait, a minute. We can use the parent and child parking,'" he says, grinning. "That's definitely one of the good experiences of being a dad."

Sir Chris called time on his glittering cycling career in 2013 having garnered an impressive six Olympic and 11 world titles. He has gone on to swap two wheels for four and next year will tackle one the most prestigious car races in the world: 24 Hours of Le Mans.

He will be driving for Nissan alongside fellow Scot Charlie Robertson, an 18-year-old rising star of the motorsport world originally from Aberfoyle but now based in Surrey. Sir Chris raced in the British GT Championship last year and will further hone those skills when he and Robertson compete in the European Le Mans Series which gets under way at Silverstone in April.

It's a steep learning curve but he's found some well-known faces willing to lend support. "I'm trying to get advice from all the different racing drivers I know," says Sir Chris. "In Scotland there is Marino and Dario Franchitti as well as Allan McNish. I'm going to try and bend their ears a bit.

"I'll take any advice I can. The aim is to get to Le Mans next year as well prepared and under-awed as I can because it's a massive event. It would be easy to get distracted by the scale of it all."

Cycling remains a huge part of his life. His eponymous bike range is a growing success and this week Sir Chris will unveil a debut clothing line, HOY Vulpine, at the London Bike Show.

He admits to an occasional pang of missing his former track cycling career, but enjoyed the novelty of being a spectator rather than competitor at the 2014 Commonwealth Games last summer.

Yet, it wouldn't have been the Games without a heroic moment from Sir Chris and that came during the opening ceremony at Celtic Park when Prince Imran of Malaysia, the Commonwealth Games Federation president, struggled to open the baton to read out the Queen's message.

Afterwards Sir Chris likened it to grappling with a Rubik's cube as proud wife Sarra posted on Twitter: "Chris Hoy always opens the jam jars in our house."

He laughs heartily at the memory. "I can't take any credit because I didn't actually open it," he insists. "We all had ear pieces in for the ceremony and I had this little voice in my ear as I got handed the baton saying: 'Right, you are going to have to run up the stairs, we're a bit behind.'

"So I ran up the stairs, heard the voice saying: 'OK, slow down, hand it across' and thought: 'Phew, timed it just right, job done.' I was then looking around, soaking up the atmosphere, when I suddenly heard shouting: 'Somebody help him!'

"[Prince Imran] said afterwards he had gone through rehearsals and knew what he was doing but it jammed. I didn't know how to open it but I tried a bit of 'push this' and 'prod that' and he finally popped it open. I was thinking: 'We got away with that - just.'"

Since Sir Chris retired, his fans are always keen to hear how his famed 27in thighs are faring. "It's not something I measure on a daily basis," he says, tongue-firmly-in-cheek. "I still ride my bike and use the gym so my body weight and shape hasn't changed drastically since I retired.

"I ride my bike most days and while a lot of that is for work in terms of formal testing and product development, mostly it's for fun. If I have a spare hour or two, I will dash out and go for a ride up the hills before I head to a meeting."

And young Callum, when will he get his first bike? The eyes of Sir Chris Hoy glitter with joy. "As soon as he can stand upright I think."

Sir Chris Hoy was speaking at round four of the Revolution Series in Glasgow. Round five takes place in London on February 27 and 28. For ticket information, visit cyclingrevolution.com or call 0844 854 2016