My quest to become a MAMIL (Middle-aged Mum In Lycra)

"Are you all right?" asked a kindly woman, pulling up in an old Fiat. They are like that in Richmond Park.

How I came to be punishing my legs and emptying my head around London's favourite cycle circuit was the result of having accepted that challenge of our age — the charity cycle ride. Ours is to Brussels via Amsterdam and Harwich, a 280km three-day jaunt, in the company of a group of Mamils — middle- aged men in Lycra, a breed sharply on the rise, according to a report last month by retail analysts Mintel.

It's all for a good cause (see below) but by the time I'd embarrassed myself in front of the Fiat lady and the deer, I was beginning to doubt if I was really up for it.

I sought help from a trainer with a reputation for getting results — Steve Halsall from Fitness 12 Retreats — who made me wear a heart monitor for three days and keep a food and exercise diary. A 1cm thick report came back full of pie charts and graphs, the most perturbing of which were entitled "stress and recovery'' and "waist girth" — no love handles allowed with these purists. Steve tactfully explained that I could be a bit fitter (when he asked if I was supple and I said I could touch my toes, he burst out laughing), adding that I wasn't replacing enough carbs while training, and my cadence was poor — ie the speed at which I pedalled. Instead of gently turning those wheels around like the London Eye, I had to drop my gears and spin, baby, spin. Who knew?

Back I went to Richmond Park, a veritable Mamils' parade at the weekend, and doubled my circuits from three to six, a total of 41 miles. One Saturday at 7am, I trailed after a colleague to Box Hill, a 45-mile three-hour round trip I had agreed to without fully considering the name of our destination. Still, even on the vertiginous ascent, when I was spinning like a mad woman with the bike virtually at a standstill, I never actually got off it.

In the meantime, I kept acquiring extra kit — gloves, wrap-around glasses, a proper cycling jacket, another long-sleeved top and a Garmin on-bike computer to keep me amused with speeds and calorie counts during the long hours of training. As any cycling widow knows, to be married to a cycle addict is to have the family's disposable income seriously depleted — just check out the forthcoming Cycle Show at Earls Court (October 8-10, cycleshow.co.uk), showcasing acres of the latest equipment, including the carbon fibre Pinarello Dogma Di2 bike, the £11,000 new toy for Mamils with money to burn.

Immersed in the callipygous world of long-distance cycling since June, I've learned three truisms: lingerie and Lycra don't mix — girls follow the boys in going commando and it's really rather liberating; life on a bike means you are often freezing, boiling or starving, sometimes all three (after 90 minutes cycling, your stored glycogen is gone and your body starts attacking fat cells) and finally that exercise endorphins are as addictive as any drug. Racing down that wooded hill by Kingston Gate is one of life's inexplicable joys you just want to keep repeating.

Not that there'll be many hills to whizz down on our trip to Brussels, as ours is apparently the flattest route possible to Europe. By the time I reach the EU capital, I hope to have mastered the art of cycling and sightseeing without falling off.

I may even have earned myself a variation of the Mamils' monicker — middle-aged mum in Lycra.

Jackie's Cause

The 100 cyclists, including London architect John Pawson and restaurateur Jeremy King, set out next Friday, September 24, to raise money for the Wellington £1 million Appeal, to be divided between the International Red Cross and Juvenile Diabetes Research Foundation. My five-year-old son Joe was diagnosed 18 months ago with type 1 diabetes, a chronic condition that requires pricking his fingers up to eight times a day and giving him a further four injections of insulin just to keep him alive.

During a recent 6am attempt to squeeze blood out of him, he pulled his hand away and said: "Anyway, you are supposed to be finding me a cure!"

"I'm trying," I said, "it costs a lot of money."
"How much?"

"Millions."

"Oh, but I don't have any dollars," he said disappointedly.

Luckily, the researchers in Cambridge who are working on our great hope for Joe — an artificial pancreas that will improve his life expectancy — take sterling.

If you'd like to make a donation, go to justgiving.com or jdrf.org.uk/donate