You can tell when you are getting old – it's when people start telling you how young you are looking.

Just as the picture with this piece will soon be replaced with a more realistic image – assuming all the light bouncing up from the zimmer-frame doesn't ruin the picture – so it is prudent to assume a more aged version of the subject will also be emerging, as this seems to be the way of things.

Given that universal truth, the latest news from our freewheeling Mayor of London, Boris Johnson, on uptake for the first RideLondon event next year has proved hugely cheering.

The Mayor reports that, just five weeks since he presided at the official RideLondon launch in Westminster, more than 25,000 cyclists have applied to take part in the RideLondon 100 bike ride – the challenge race which will cover a similar route to the Olympic road race course as it winds its way out from the Queen Elizabeth Olympic Park and out into the hills of Surrey before returning for a capital finish.

Johnson, of course, is already an experienced urban cyclist. As it happened, I saw him wheeling in to the Westminster launch venue on the appointed day, just seconds after the passing of the Horse Guards, in all their vivid pageantry and pomp, who were presumably trotting off towards their eventual ceremonial destination of Buckingham Palace.

In the circumstances, the Mayor's arrival had a distinct feeling of After The Lord Mayor's Show about it – especially as he had turned up at a side entrance.

"Hi de hi", he announced to the one official in a attendance as he dismounted, his suit straining only slightly as he did so. And then the blond barnet had disappeared within.

Walking round to the main entrance, where several camera crews and photographers were waiting for something or someone, I was passed by a harassed man who might possibly have been another official who had been expecting the Mayor's arrival at the front entrance but had just heard the Mayor in question had slid in by a side door.

Or he might just have been a man in a bad mood.

Anyway, Boris was his usual charming-whether-you-want-to-be-charmed-or-not self at the launch. On reflection, his humour works in the way a skilfully applied rubber hammer works upon the knee, triggering a series of involuntary reactions.

Boris Johnson launched RideLondon with the help of double Olympic gold medallist Laura Trott

He's got a range of verbal tricks – and it has to be said, a sensational turn of phrase. But then he's bringing a second runway at Stansted Airport back into the reckoning...wrong, wrong...must be resisted...must try...must...

One of his favourite hammer applications works something like this: "Good morning...if that's the phrase I'm looking for..."

I know, I know. On paper – sorry, on screen – it doesn't look like anything. But when Johnson delivers this particular verbal riff he does something with his chin and his eyebrows and, I don't know how or why, one finds oneself chuckling. It's in the timing, I think. It's almost sinister.

Do I digress? I fear I do.

So Johnson has announced that 25,000 cyclists – a third of the eventual maximum total – have taken the plunge and committed themselves to the 100 miles race. He, indeed, confirmed his own intention to take part in the race when he answered questions at the launch.

Before we go any further, and just to prevent any misunderstanding, may I just say that I have no intention of doing the same thing.

I cycled at university – and, as I believe I have previously asked, if anyone knows the whereabouts of a bike marked F144 and last seen – locked – outside the Pike and Eel pub in Cambridge, in 1979, then I will be very happy to hear the news.

I have cycled intermittently since, most recently on holiday this summer, and there is no escaping the big drawback of this sport, which I believe can be summed up in just two words: sore arse.

Running is better than cycling. It's just a fact. And I am currently preparing for a second bash at the Virgin London Marathon next year.

But certain facts have to be faced, and in physiological terms it has to be admitted that cycling is less wearing on joints and – well joints mainly – than proceeding on foot. Which means that, like a range of mountains viewed beyond the nearest range, the RideLondon 100 race, a kind of London marathon on wheels involving riders good, bad and indifferent, lies beyond the foot race so inspiredly and inspiringly established in the capital in 1981.

Not yet, but at some time in the near future, I hope to embrace it. I will probably start with the eight-mile RideLondon Freecycle first, however.

Mike Rowbottom, one of Britain's most talented sportswriters, has covered the past five Summer and four Winter Olympics for The Independent. Previously he has worked for the Daily Mail, The Times, The Observer, the Sunday Correspondent and The Guardian. He is now chief feature writer for insidethegames.