I was desperate to get a black and gold Raleigh Super Burner when I was six but the price was £105, which felt like a million. My parents said they’d contribute half if I raised the other, to teach me the value of money and hard work. What I did was wait until guests at my parents’ dinner parties had drunk a few glasses of wine, then I’d walk in – ready for bed in my dressing gown – and show them a catalogue and say: “This is the bike I’m saving for, but I’ve only got £2.50 so far.” They’d give me fivers and I had the Burner in no time.

Mum was a nurse and worked night shifts, but cooked all our evening meals and breakfasts. Once she went to Greece but was terrified that me, Dad and my sister would get malnutrition and not survive her absence. So, a microwave appeared and she home-cooked and froze two weeks’ worth of hearty meals. I remember her saying, “Wait for the ping, then eat.” Without Mum knowing, during many of her night shifts, Dad and I would use the wooden kitchen table we ate meals at as our workbench, rather than strip down my mountain bike in the dark outside. There were hanging lights we’d raise up and the bike could go upside down on the table. Each time there’d be mud, grease and oil everywhere, but we’d elaborately clear up the mess and then I’d take the bike – gleaming – to my bedroom and fall asleep gazing at it. Sometimes, Mum would spot a smear at breakfast and ask, “How did that get there?” and we’d say, “We’ve absolutely no idea.”

If I smell a burger stand I get nervous. It takes me back to BMX tracks as a kid. The best burgers were made with round fried sausage meat. But I’ll smell any greasy burger and suddenly have the sense I’m at an event and it’s a big weekend. I particularly remember the smell of burgers and bratwurst drifting across Cottbus Velodrome in Germany.

On Friday nights, Dad and I would travel in the Citroen estate from Scotland to maybe the south of England for a race meeting, with a cooler box, prepared by Mum, of a weekend’s worth of Mars bars and sandwiches. Each sandwich was wrapped in foil, so the contents were a lucky dip. But if it was, say, cold sliced sausages with tomato sauce it would soon get soggy, which would be much better to discover on Saturday rather than Sunday.

I worked in the shop Recycling in Edinburgh – rebuilding rusty bikes – to get my finances together to buy parts to make the best bike for my next season. But I’d spend half of every day’s wages at the nearby deli. I probably only raised £500 that year because their fresh-cut meats, salami, salads and rolls were incredible. From the moment I arrived at work I’d be thinking about lunch.

I transferred from doing physics and maths at St Andrews to sports science – when it was brand new – back at Edinburgh. I thought, if the guys I’m racing against don’t know about this stuff, I’ll have advantages, get ahead. It was the start of looking for all the possible ways that I could up my sport performance: what and when to eat for specific sports, and when, where and how to gain muscle mass and the importance, beyond carbs, of proteins, amino acids, hydration and all these things. It’s not about having calories, it’s about having useful calories.

Before I got into sprint racing, when I was road racing, you’d see me eating at the saddle all the time. A lot of the time from the back pocket – suitable for bananas, little gel sachets and energy bars. The less chewy, the easier it is to concentrate. When passed from the roadside, in disposable musettes, there’s weight reduction over the course of the race. But when you skip eating, after two hours of really intense cycling, your body’s tank of glycogen is on empty and it’s not a matter of slowing down but being barely able to move. It always looks comical but it’s dangerous and not pleasant. I once remember the feeling, when out training for a world championship medal, that all I wanted to do on the bike was sleep.

The worst thing you can do in sport is change your routine right before an event, rather than in training. I was violently sick the first time I took massive scoops of sodium bicarbonate alkaline with my food before a race. It was to help neutralise the lactic acid my body would produce around the 20-25-second mark. What alkaline does is delay, for a second, the onset of a very painful sting from the acid. As I won my first championship gold medal by just 1/1,000th of a second – 15mm – in Copenhagen in 2002, it was quite a factor.

You get dope-tested after a race and have to be available for an hour each day. On top of that there’s random urine testing. It’s sod’s law but usually the testers arrive early in the morning and almost invariably just after you’ve flushed your first pee of the day. It’s unbelievable, uncanny. You press flush and it’s ding-dong. So they’ll stand waiting for ages while you drink coffee, desperately trying to urinate again.

I arrived, exhausted from a 24-hour flight, at a training camp prior to the 2000 Sydney Olympics. I slept deeply for a few hours then woke up incredibly hungry. I went downstairs and ate 15 Danish pastries, one after the other. It was ridiculous but they were so fresh and the most amazing things I’d ever tasted.

Athletes are obsessional about food. I used to have 6,000 calories a day. Nowadays, life seems to revolve more around our kid’s food. He was 11 weeks premature and so tiny when he came out. So it’s a salvation whenever he has a good meal – if he eats well – and a joy when he gets into a new texture and taste.

I was seen scoffing a double cheeseburger and fries and a McChicken sandwich at 4am in the Olympic village in Beijing in 2008. At any Olympic village there’s a massive long dining hall with cuisines from every continent, with a McDonald’s at the end, with no one in there. But as the three weeks pass and athletes finish their races, McDonald’s becomes busier and busier, and by the end everyone wants some real dirty burgers to scratch the itch.

I think Sydney was the only Olympics where we weren’t allowed alcohol in the village. So, on the day of the closing ceremony, we went out to an off-licence with empty sports drinks bottles to fill them up with vodka and Red Bull, but Jason Queally didn’t bring a bottle and so went rummaging around in a litter bin in the street. Athletes walked past saying: “Isn’t that a gold medalist?”

I was in La Paz in Bolivia for a just a few days to attempt to break the speed record on the highest cycle track in the world. I stayed in the top-floor apartment in the Ritz Plaza Hotel, laying on my bed for the first 24 hours on oxygen. Then when we held a party and I had a few beers I suddenly thought my head had been put in a vice. Altitude plus alcohol. It was the most unbelievably horrendous migraine imaginable.

In the 18 months prior to the London Olympics I had wine on just four occasions – Christmas Day, New Year’s Eve, the last night of the World Championships, and my birthday. The hard part, now that I’ve retired from competition, is that there’s no reason not to drink wine, and I do enjoy my reds. When I was a kid, my dad used to talk about wine and I thought, “God, it’s so boring” – such a cliche, a middle-aged man talking about wine. I don’t know what happened to me but I just love the stuff. And I remember back in school, the careers computer suggested I become a brewer.

My ultimate food hell was in Moscow in 1996. We were served lukewarm soup looking like dishwater with a lump of meat. I had a few disgustingly sour sips then tried to chew on the lump, which was pure bone, so I spat it back into the bowl. The waitress walked back over, put my bowl on a trolley, and served it to a member of the Czech team. I thought: “Christ, what nationality got it before me?” For four weeks afterwards, I stuck to sardines and Wagon Wheels.

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