How many bicycles do you have? How many do you want to have?
For many people, just the one is enough - a hybrid bike, say, fit for most purposes. Or, maybe two or three, for different activities – one for the road, one for the mountains.
But for others, accumulating bikes becomes a hobby, a passion – or something that just seems to keep randomly happening.
There are, of course, on "the ideal number of bikes to own".
The first is N+1, where N = the number of bicycles you already have.
This calculation must be balanced against the possibilities of S-1, where S = the number of bicycles that will result in your partner moving out.
"How many bikes do I have? Thirty-one!" Amy Gillett Foundation chairman Mark Textor told me this week, without a moment's hesitation.
Off the top of his head, there's two electric bikes, a trike, a velomobile ("for Alice Springs to Darwin next year"), some old trackies, a Slingshot road bike with a cable for a down tube, various mountain and road bikes, a collapsible Bike Friday, a unicycle he's learning to ride ("it's very difficult"), a "clown" bike, some recumbents and a tandem. Oh, and two Brompton foldable bikes ("why I've got two is beyond me").
About 10 are in storage, including some ex-Tour de France Pinarellos, but Textor says the rest are mostly good to go, needing little more than fresh air in the tyres.
One of his special interest is recumbents – the bike that looks like it's crossed with a La-Z-Boy chair.
"If you've got a long, open ride and you're by yourself, you're bonkers if you didn't ride a recumbent," he says. "You can go all day, and you're fatigued, but you're not hurting. That's why you get hooked on them. They're comfortable and they're bloody fast."
He keeps a Brompton handy for his business trips as a pollster and political strategist, saying that a bike is the fastest way to get around cities like London and Milan.
Textor says he has always had bikes in his life - he raced competitively from a young age - and seldom gets rid of an old one. At home, bikes are "all over the place, it's just ridiculous, tyres everywhere, bikes folded up".
Another bike agglomerator is Neil Irvine, a cycling author whose name can be spotted on various Lonely Planet cycling guides.
"The house is pretty much full now, I'm having trouble finding anywhere to put the Lynskey," he says, referring to his latest titanium-frame purchase.
Like beloved family pets, the more popular ones get to live with the humans. "Twelve in the house," he concludes, after tallying up the various vehicles used by his family of four, before rattling off a list of kids' bikes, mountain bikes, utility bikes and retired frames stored in the garage … "that'd be another nine, plus the cargo trailer".
Irvine is spared the dangers of "S-1" as he met his wife while working for a cycling organisation – they left their wedding reception on a tandem, and have toured extensively together, often with their children in tow.
One and only
On the opposite end of this scale is a mate of mine who had just one bike for two decades while racking up massive distances, including touring in Spain, France "about four times", Scandinavia and multiple visits to New Zealand.
"It just went so well," he says of his 1993 Giant Yukon mountain bike with slick tyres. "When parts would break I'd get them replaced, but it felt comfortable, a steel frame, solid and reliable."
He recently bought a Trek hybrid, and now tends to rent bikes at travel destinations to beat luggage costs, but says he'd probably still favour the Giant for any further trips.
As for me, I've got two bikes – a road bike and a touring/commuting/utility bike (oh, wait – plus an old frame in storage).
I feel I'm protected from the risks of random purchases, when you stroll into a shop looking for new socks, and come out with a new bike – being ridiculously tall, I struggle to find bikes to fit me. And living in a small apartment, I'm not sure where I'll put another bike.
Still, a friend on the other side of the height equation has accumulated five bikes with non-standard 650c wheels, and packs them neatly into the corner of a garage-less home using pulleys and wall brackets. Where there's a will, there's a way.
I've been resisting the lure of mountain biking, but lately the concept of two-wheeled wilderness experiences, without the eternal whooshing of passing cars, has become increasingly attractive. Maybe just one more bike, and that's it ...
How many bikes do you have? How many do you want to have?
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