In the course of his round-the-world journey, Ted Simon has never yet been a victim of crime. But he knows plenty of people who have. And, as he reports in his latest dispatch, he now faces his toughest challenge yet: Colombia ...

On Christmas Eve, at this small and pleasant hotel in Quito, two Ecuadorean men checked in. Apparently they spent most of the evening playing pool before going to bed. At three in the morning they came down from their rooms with guns, tied up the night watchman and rather gratuitously beat him, stole what money they could find, took the hotel computers and, as a last-minute inspiration, made off with the balls from the pool table.

I heard about this from Maurice Engels, a long-time Paris Match photographer who happens to be staying here, too. It explained why we had to play chess rather than pool.

He himself had just come out of hospital. A week earlier he was walking in a busy restaurant area with a friend and his dog when they were attacked by a gang of five men. A metal pipe to the skull laid him on the ground. They ripped his pockets open and found all of $10. They missed his passport, but got a very expensive camera for their pains.

Later, in the Red Cross ambulance, Maurice was asked to show his passport, and the paramedics stole the $60 he kept in it for emergencies.

I am quite accustomed to hearing these stories, and have mustered a fair collection of them. When we were filming in Tunis and the crew was unloading equipment on a busy street, a passer-by simply reached down, picked up a case and walked on with it, scarcely even breaking his stride. In Addis Ababa, while I was in a hotel lounge waiting out a student riot, a young Englishwoman came in, badly bruised and bleeding. She had got off a bus with her backpack when several men, taking advantage of the general chaos, had seized and half strangled her, kicked her in the head, and ripped her pack open. When her stuff fell to the ground and they dived for it she was able to break free and run.

In Nairobi, I stayed one night with a friend and his family in a secure compound, but in the morning one of the wheels of his wife's car was gone. A few days later they came back for the other three.

The same friend was driving through Nairobi with his assistant when, at a traffic jam, two men got in on either side of them with Uzis and directed him to drive out of town. It occurred to him that if only he and his assistant could arrange to duck simultaneously the two men would shoot each other, but he couldn't come up with a plan before they were kicked out of their car, and the men drove off with it.

That was the penalty for forgetting to lock the doors. In Johannesburg, by all accounts, locked doors are no protection. Carjackers shoot through the glass, to kill. Just about everybody claims to have been either shot at or to know friends who have, and stories of men marching in from nowhere with guns and shooting indiscriminately are commonplace.

And yet in Johannesburg, as in Quito and elsewhere, people go about their business very much as though none of this was happening, and, of course, most of the time it doesn't happen. The odds are still good enough. And the pickings are good, too. The victims are so much better-off than their attackers, and it is the sharp disparities between rich and poor that provide the good life they lead under siege.

The familiar description of Kenya as a place where one-third of the population employs another third to protect it from the other third is now becoming generally true. In most of the big cities, armies of private security guards patrol the wealthier suburbs and linger outside the banks with machine guns. Most of them, I believe, have had no more training than it takes to strap on their jackets. In Egypt the conscript army is used for the same purpose.

In Peru the police force seemed to be hugely inflated. There were silver Policia Nacional Toyotas stationed at 12-mile intervals all along the Pan-American highway, and transit police stopped me twice for bribes. In Lima, they are trying to contain police corruption by recruiting women. Fleets of very attractive policewomen in flatteringly tight uniforms ride big white Harleys around the city, and are said to be unbribable, but the general view is that their effect is largely cosmetic.

The only serious purpose I can offer for repeating a journey I made 27 years ago is to give some account of how things have changed. I have come 25,000 miles now through Africa and much of South America, and things are falling into place. In all of this territory, people with any kind of means live behind bars. They are, in effect, prisoners of their own device. The amount of protective ironwork around homes is astounding. Most shops don't have doors; they have steel shutters, and the rest have both. The number of people employed as security guards is phenomenal, and I can only wish I had an investment in the flak jacket business.

Without any doubt the most startling change I've seen is in the way crime has become an acceptable way for many poor people to solve their personal problems, and resolve their frustrations.

It seems to me that crime in the good old days was generally either petty, as in the pickpockets my mother was always warning me about, or organised, à la Capone and Kray. To do violent stuff with guns you generally needed some kind of a mob behind you. Nowadays, the crime everyone is scared of is very much a freelance affair, committed by individuals or small gangs, often spontaneously, and often drug-related. One could see this as an automatic consequence of the drift to the cities, which is happening everywhere. Population growth is one cause. Disruption of the countryside by Cold War policies is another. The carrot is the fantasy of urban lifestyles promoted by the media. The rural habits that link honesty to self-respect are easily broken when the city fails to provide a living.

Personally, I date the beginnings of it to the day in 1964 when Kitty Genovese died a long and agonising death in the courtyard of her New York apartment block, and nobody answered her screams for help. Street violence grew and spread endemically across the country. It led to the affluent suburbs, the gated communities, and the ghettos. Now, 30 years later, the rest of the world is catching up.

What is so obviously happening everywhere now is a reorganisation of society according to these principles, and it is difficult to see why the process should stop. The kind of world in which I was raised, where arbitrary violence in public places was almost unheard of, looks more and more now like a brief aberration. It seems quite apt that the United States should have led the way in this, as in all other social changes. In fact, the culture of violence is as much a Western export as the consumer goods that are its object and the weapons that are used to acquire them.

As for myself, I appear to have led a charmed life. I have never felt under threat, either on or off the bike. In fact, none of the crime stories I've heard involves bikers. I suspect that this has a lot to do with the way we travel. Although motorcycles are much more common these days, people who travel long distances on them are still relatively rare. We are not a natural target for hijacking on the road. Because the bikes are so central to our purpose and so valuable in themselves, we take care to keep them safe when we're not riding them. And when we're just walking around, we're unlikely to be carrying much of value to attract muggers.

Well, I hope I'm right. So far I've been depending on it, but I'm about to run into a different kind of situation where none of these factors applies. In fact, I'm about to become very vulnerable indeed. I'm about to ride through Colombia.

Of course, kidnapping is a crime, but not in the eyes of the guerrilla groups that command the territory I will be riding through. And if I needed reminding of that fact, Glen Heggstad has just done me that service. His first words to me were: "I want to convince you to change your mind about riding through Colombia. You could not possibly imagine anything worse than what happened to me."

Two months ago he was riding between Bogota and Medellin on a fine but empty highway when he was stopped by a group of young men in black uniforms jabbing Chinese assault rifles into his ribs. Glen is a big man, 6ft 4ins, and justifiably proud of his physical prowess, but, of course, he was helpless to resist. They seized what they wanted, abandoned the bike, and marched off with him into the jungle, not before firing off a pistol alongside his skull to make sure he understood.

He is reluctant to talk too much about what happened. But I got the general picture: of mock-executions, of starvation, of torture. I also had the thrill of seeing, in a plastic bag, the rather large grub that had hatched under his skin and then worked its way out. The details of his release are still confidential. There were other hostages, and they are still there.

Glen is an American, which inspired their special hatred. He was riding an olive-green bike that could have been taken as military. Many motorcyclists have travelled safely through Colombia from north to south on their way to Tierra del Fuego. I repeat these facts to myself as a mantra. By the time you read this I hope and expect to have arrived safely in Cartagena on the Caribbean coast, ready and willing to take my chances on ordinary crime.

For more information on Ted Simon's journey, go to 'Jupiter's Travels', Ted Simon's account of his original journey around the world, is published by Penguin, price £7.99, ISBN 0140054103.