In the Irish writer Flann O’Brien’s wonderful novel, The Third Policeman, two of the characters – Sergeant Pluck and Gilhaney – have a lengthy discussion about various aspects of the bicycle. Part of it goes like this:

“I do not believe in the three-speed gear at all,” the Sergeant was saying, “it is a new-fangled instrument, it crucifies the legs, the half of the accidents are due to it.” “It is a power for the hills,” said Gilhaney, “as good as an extra pair of pins, or a diminutive petrol motor.”

Now, it may just be that Sergeant Pluck has gained a lot of adherents in recent years, or it may be simply the cyclical vagaries of fashion, but there’s no doubt that single-speed bikes are enjoying a big surge in popularity right now. Any bike store I’ve been to in the past couple of years has a number of single-speed machines on offer, which certainly wouldn’t have been the case a decade ago. And it’s equally clear that these bikes are intended as street machines, aimed squarely at urban cyclists. So what’s it all about? And are you with the Sergeant, or Gilhaney?

Over the years, more and more gears became available on bikes. From the early two- and three-speed hub gears to the 15-speed systems of today, from the pre-derailleur chain shifter to the current maximum of eleven sprockets on the rear block, it’s been nothing but increase.

But there’s always been something fundamental about a single-speed bike – its simplicity, its lack of fuss – and I think that this helps explain its enduring presence in the marketplace, and its current popularity. After all, when you’re riding round town, with no long journeys involved, what would you really do with, say, 24 gears? How many would you use? Judging by a lot of cyclists I’ve seen in various cities, not more than three! So, it’s not such a great step down to only having one.

In addition, if you have but the single gear you’ll never find yourself stopped or stuck in the wrong one – how could you be? Setting off from the lights, cruising, quick sprints – they’re all comfortably handled by the one gear available. Not great if you live somewhere with big hills, I guess, but how many of us do? I regularly rode a single-speed bike round a city with plenty of short, sharp hills for a few years; once you get used to putting in the extra effort the hills are OK. I doubt the same would apply to long, arduous climbs, but then you don’t find those in many cities.

My own single-speed bike also has a fixed wheel, which brings it even closer to first bicycle principles. But that’s something to write about another time.

In the meantime, if you haven’t read The Third Policeman, get hold of a copy. It’s well worth it.