I am a frightful cycling snob. I scoff at casual cyclists who know no better than to puff along in the wrong gear, bereft of lycra, with soggy tyres and the saddle set too low for efficient leg extension. They neither know nor care about their best times between home and the office, or that some pedestrians and wind-blown KFC wrappers are moving more quickly than they are. They even seem content to queue like saps with the tin-box traffic, never taking to the pavement or jumping a pointless red light, and bouncing along in the gutter when the traffic starts to move. They probably don't even shave their legs, at least not for cycling purposes. Some of them dismount for steep hills.

I don't shave my legs, if only because my calves aren't as exquisite as they once were. In all other respects, I like to think I've earned my cleats. When I started commuting to work by cycle, it wasn't enough to equal the journey time by bus or car. I was finally in control of my commute and wanted to beat the opposition. This meant getting my heart and my sweat glands pumping, which is incompatible with cycling in office clothes unless you like to work alone. So began the lycra revolution. Before I knew it, I'd bought a nice road bike and started clocking up the rural miles, neurotically competing against my own averages and revelling in the speed, freedom and calves like sculpted marble.

Then I lost a big argument with a small hatchback on a fast country road and have spent the last year recovering from a broken back. Even as I flew through the air, I acknowledged that my time had come. I'd had so many near misses with traffic in my cycling life that sooner or later one of them was bound to get me. Cycling in the city, I defended myself aggressively; keeping pace with the traffic, taking as much space as I could to discourage silly overtakes, slapping rear wings to frighten drivers who'd stupidly cut me up, gingerly taking to the pavement when traffic was just too crammed or dangerous to cycle through. On roads with a theoretical 60mph limit, the defensive options are more limited. The fact is that most cyclists have good reason to defend their road-space aggressively.

Cycling etiquette is back in the news following the brutal shopping bag attack by an 84 year old baroness and pedestrian on a defenceless young cyclist. Apparently, he'd piqued her ire by running a red light. Whether he nearly collided with her or not I can't say; but she should be commended for her athleticism.

Legally she was plainly wrong. Sadly, we're not entitled to mete out instant retribution for breaches of the Road Traffic Act. If we were, the roads would soon be jammed with blood-drenched wreckage and police tape. Morally, things are less clear. If the buffoon struck her or nearly did, he deserves the death of a thousand Waitrose prawn & mayo sandwiches. If he was nowhere near hitting her, she really should find something better to be irked by: considering where she works, how hard could that be?

Most cyclists would confess to running red lights. When I'm cycling home from work at 1am and I come to an empty junction on red, I cheerfully ignore the signal. Illegal, certainly; but immoral? It would be lunacy to think this way in a car, which is heavier, faster and easily lethal to others, whereas a cyclist tends only to be lethal to himself.

If I were reported for jumping a red on my bike, I'd have to hold my hands up and take my fine. Many road traffic offences are offences of strict liability. To be guilty of speeding, for example, you only have to be shown to have transgressed the speed limit, regardless of your knowledge or intent, how competent you were, or whether you were the only vehicle on a three lane stretch of motorway on a bright sunny day (not that I'm bitter).

Which brings me to the irksome suggestion that cycles should be registered as cars are so that marauding cyclists may more easily be brought to justice. There are plenty of cyclists out there who deserve to be harassed; scallies bowling pedestrians aside on BMX's, eco-terrorist cycle couriers who would rather crash any number of lights than change gear; sluggards on borrowed mountain bike who just won't get out of the way of faster cycles. We should therefore let PC's and PCSO's harass them using good sense and discretion, in the same way that we used to have traffic cops to harass not just speeders, but the incompetent motorist in all his guises. The fact that the application is lacking doesn't mean the law isn't there.

As a motorist, I am a potential milch cow, liable to faceless sucker-justice if I happen to trip a speed camera, whatever the circumstances. I say sucker-justice because I've registered my car, insure it and pay my road tax; those who do none of these things often have little to fear from automated enforcement. If cycles were registered, wouldn't this principle just be extended wholesale? And how exactly would escalating the cost and bureaucracy of cycling tempt people out of their cars and the cardiac wards and help save the planet?

Surely we should just recognise that grand dowagers may sometimes be entitled to swing a bag at a miscreant, and cyclists may sometimes be entitled to make vulgar gestures at the law.