Until a couple of years ago, I lived one block away from an uncontrolled T-junction. On the other side was a small co-op supermarket, which was my closest shop. Getting to it was a very short journey on foot.

I don't drive - by which, I mean I can drive, but I wisely choose not to. I was last behind the wheel of a car in 1991, returning a rental to Boston airport, and only really drove in total for about a year before that, after passing my test in 1983, on the third go.

It became clear that death would have less sting-a-ling-ling without me on the road, absent-mindedly going into the back of three parked cars, attention distracted by an election sign on a lawn. Thanks to astigmatism and terrible depth perception, I could never judge whether or not I had a large enough gap to change lanes.

So I am, by choice, a pedestrian; a user of public transport; and late at night, having been mugged half a block from my front door a year ago, taxis.

Thank God I moved, because getting to this shop could be a heart-stopping dice with death. T-junctions are a nightmare for a pedestrian to cross because you have to look to your left, and also behind you, before you step off the pavement.

The cars coming from the rear can't see you until they are close to the turn and they don't always indicate if there's no traffic behind them. To this difficulty has been added a new, frightening dimension: The cyclist, the most morally pure of road users, the ethical standard-bearer for healthy living, a challenge to climate change and the ones who are starting to completely terrify me for their unpredictability and aggression.

An incident from that T-junction illustrates the problem. The road is a busy one, wide enough for two lanes of cars in each direction. Two lanes of drivers saw me hovering on the pavement and slowed to allow me to cross. I got to just past the first set of cars, when up through the centre came a cyclist, barrelling along at high speed, hunched over his handlebars, causing me to jump out of the way to avoid him, trip and go down flat on my face in the middle of the road.

This sight didn't deter the cyclist, who disappeared up the road, while two motorists got out of their cars to help me. No chance of getting the cyclist's number plate, of course. They don't have them.

Why did he (there are female cyclists in London, but not as many) do this? I assume because he was trying to evade the cars, which is reasonable, given how many cyclist deaths are caused by larger vehicles. But pedestrians are not vehicles and cyclist safety is coming at our expense.

We are their most vulnerable competition, yet treated as if we don't exist. Cyclists are behaving in ways that pedestrians cannot predict, or understand, or modify our behaviour to take into account. It's an act of often-misplaced trust that they will do what they are supposed to do.

Here is a traffic light. My sense is that drivers tend, overwhelmingly, to stop at them, but in a normal day of pedestrian road use, I can repeatedly observe cyclists running red lights and also coming up onto pavements, scattering screaming passers-by. A now-quaint cycling accessory, the bell, seems to have gone completely out of fashion - I can't remember the last time I heard one, or saw a cyclist putting his arm out to indicate.

I can't ride a bicycle. As a child, I begged and nagged for one. I lived in a quiet suburb and cycling around the neighbourhood would have been safe and healthy. In the early 1960s, it was a normal rite of passage for 10-year-olds to receive a bike for their birthdays, but I never did.

The reason for this was that, a decade earlier, my father had knocked over a cyclist. The accident had been deemed the bike-rider's fault and Dad was exonerated. "Cyclists are a menace on the roads," he would shout when I pleaded with him for a bike. So, I never learnt to ride one in childhood and when I tried, as an adult, the falling off was too painful.

Now, I find myself turning into my father, muttering, "cyclists are a bloody menace on the roads", or at least, London roads, which are choked with competing types of traffic, HGV vehicles being the most intimidating, and pedestrians the most nakedly at everyone else's mercy.

I'm aware that many - maybe most - cyclists are law-abiding and stop at red lights and don't speed through T-junctions when pedestrians are crossing, or ride on pavements, and that even terrible cyclists don't kill pedestrians. But as Father Ted remarked about paedophile priests: "Say, if there're 200 million priests in the world and 5 per cent of them are paedophiles, that's still only 10 million."

The percentage of a***hole cyclists may be a minority, but it's a minority large enough to make crossing roads an exercise in guesswork as to whether the one coming towards you recognises that you even exist.

Not that pedestrians are without our daily transgressions. Walking diagonally across intersections, stepping out into traffic, wandering around with headphones on so we can't hear cars coming: All of these are hazards to other road users.

But only cyclists proclaim themselves to be standard-bearers for an ethical higher calling and mode of being, more suited to a lycra-clad cult than simply a mode of transportation.

Having complained about cyclists before, on Twitter, I'm geared up, so to speak, for the assault that's going to come at me from the cycling lobby. I've mercifully evaded, so far, the Twitter mob in full pitchfork-wielding frenzy; have not been called, as the two women candidates in this summer's Labour leadership contest were repeatedly, a "witch" or "c**t".

Still, I have the expertise to know what to do with trolls, which is mute, don't block . Trolls assault complete strangers in order to get a reaction. They're attention-seekers and I know, to my cost, the consequences of engaging with that type. I once tried to get a blogger to correct something he had written about me that was simply factually inaccurate, an endeavour which went on, fruitlessly, for years.

Trolls collect their blocked badges with pride, the distinction of possessing a voice so threatening that the powerful are trying to close it down. Being blocked by George Galloway, or Louise Mensch, or Alastair Campbell is a mark of speaking truth to power.

The mute button is a far more subtle weapon, since the person on the other end doesn't know that they have been muted and goes on tweeting at you, often for years on end, in a state of complete invisibility.

To be silenced is one thing, but to be ignored for your irrelevance is quite different, and more suited to those tweeters with seven followers, and a death's head and a pair of crossed saw-tooth knives as their avatar.

Though I am Pollyannaish enough to believe that that would never be the assumed identity of a cyclist. I'm sure you're all lovely when out of the saddle.

THE GUARDIAN