Cycling is a collection of habits and muscle memories, learned in childhood - usually with the help of stabilisers - that are never wholly forgotten. After all, we encourage people to revisit a long-neglected activity with the expression, "It's just like riding a bike."
For me, freewheeling has been second nature for as long as I have been riding. I have also always favoured a conventional multi-geared bicycle: it makes sense on downhills to click on to the smallest rear cog and blast along, and to choose a low gear for going up. Integral to this is the ability to glide along without pedalling.
Why would anyone give up their gears and revert to the kind of primitive, one-speed-fits-all machine, used more than a century ago when the Tour de France wasn't even a gleam in the eye of its first director, Henri Desgrange? He resisted the use of variable gears, fearing it would detract from the heroic efforts of his racers, one of whom, Octave Lapize, branded race officials "assassins" after dragging himself and his gearless bike over the Pyrenees in 1910.
Nowadays, cycling magazines are full of breathless reports on the latest electronic gear shifters. But there's a growing place, too, for single-speed bicycles, similar to those of the Desgrange era. Until recently, the sole preserve of city bike messengers, the single speed fixie and its anti-establishment style is spreading.
Commercial models are mostly sold with a flip-flop rear wheel - and two brakes. On one side of the axle is a standard freewheel that still allows you to coast along: anathema to the hardcore fixie. On the flip side is the true solitary fixed sprocket whose movement is married to that of the wheel.
A fixie is a relatively cheap proposition. Most prêt à pédaler bikes sell for around £500. There is a growing range from the big manufacturers, including Specialized and Trek. Independent companies such as Pearson of Surrey, Condor and Surly have their own take on the affordable single-speed. If you're after maximum street cred - and have the mechanical know-how - you can take the DIY path, converting your existing bike into a fixie for £100-£200.
Since the first rule of the fixie is "Don't even think about freewheeling", adapting to riding one is not easy. Try coasting downhill: you'll end up with your legs twisted into a reef knot.
If you're worried that repeatedly using a fixed back wheel could cause knee problems, opinions differ. William Pearson, of Pearson, says the key to slowing down is to "put your legs into neutral" and use the front brake. Debra Rolfe, development officer for Britain's largest cycling organisation, the CTC, has never encountered anyone with severe knee injuries in her many years as a fixie rider. She thinks "the claim that riding a fixed gear causes knee problems is a bit of an urban legend". But Chris Juden, CTC's senior technical officer, urges caution, especially to those with ageing joints. "Pushing too hard on a high gear is a known cause of trouble," he says. "Riding fixed is not for anyone who has a tendency to knee problems".
Deciding whether it's healthy is one thing. Is it legal? The law says bikes should have two brakes, one for each wheel. You'll see many city couriers escaping through the chinks in jammed- up traffic with only one brake lever on their handlebars. The CTC says there's no clear definition of how braking systems should operate. So, at a pinch, these riders could argue that their front brake, plus the fixed back wheel, actually amount to the required two braking mechanisms.
Fixie riding is purer, smoother and more organic, according to the enthusiasts. You have to read the road more carefully and regulate your pedal speed accordingly. Because your legs and the cranks are in perpetual motion, you and the bike feel merged like a single organism, just as Flann O'Brien described in his surreal masterpiece, The Third Policeman.
Mechanical reliability and low maintenance are the other big pluses.
Going down steep hills is probably best avoided, though. The sharper the incline, the faster your short fat hairy legs, to quote Eric Morecambe, will be spinning.
I'm a convert to "singledom", but for now retain the ability to freewheel. There's nothing quite as liberating as manoeuvring through rush-hour traffic without having to bother about gears. Getting through a gap means pedalling harder - simple. I'm well on the way to shaking off the freewheeling habit altogether. My new fixation with the fixie is swiftly turning into a full-blown addiction.
