South from the Limpopo: Travels through South Africa by Dervla Murphy John Murray 432pp, £18.99 in UKWhen she crossed the River Limpopo, the border between Zimbabwe and South Africa, and reached the black township of Messina in the northern Transvaal, Dervla Murphy astonished two friendly young blacks with her travel plans. "They thought me quite mad," she relates, "an old woman planning to cycle around South Africa!"

I thought so too when I began reading these accounts of three bicycle treks throughout all nine provinces of that racially complex, politically volatile republic.

The international travel writer from Co Waterford was 62 when she set out on her arduous, possibly dangerous, 6,000-mile survey of South Africa before, during and after the 1994 election which established majority black rule where once the white minority had presided harshly over apartheid. I knew she was a courageous veteran explorer of difficult countries, but this time wasn't she undertaking too much?

Apparently not. The fact that she was a woman of advanced years touring in great discomfort in extreme weather conditions on a shoestring budget endeared her to South Africans of all colours and social conditions, especially the poor. As for her vulnerability in places where so many men carried guns, one of the young blacks in Messina was encouraging: "But you'll be safe," he assured her. "Even APLA [Azanian People's Liberation Army] wouldn't attack a mama on a bike!"

In Zimbabwe, she collected the bicycle she had stored there after riding it from Kenya on a previous daring expedition, for another book. She called the bicycle Lear and referred to "him" as affectionately as Don Quixote regarded his Rocinante. In South Africa, until "he" was stolen, Lear enabled Murphy to travel as many as eighty miles a day, even over rough roads, by mid-afternoon. Rapid progress allowed her time to get to know all sorts of people - farmers, shopkeepers, policemen, teachers, politicians, barmen, prostitutes and the innumerable unemployed.

The theft of Lear was initially devastating. Fortunately, however, the thief discarded the panniers in which the manuscript pages of Murphy's work-in-progress were kept, so they were not lost. But Lear was never regained or replaced with a machine of comparable excellence. Here, surely, was a case for easily arranged commercial sponsorship, but evidently that would have been against Murphy's self-imposed rules of austerity. She often ate whatever the poorest locals ate, including pap (mealie porridge) and stew of goat's intestines.

She bought a cheap bicycle with unreliable brakes, no mudguards and tyres susceptible to punctures (Lear's superior tyres cost £150 each), and carried on. She named it Chris, in honour of Chris Hani, the Chief of Staff of the African National Congress and General Secretary of the South African Communist Party, who was assassinated by a right-wing Polish immigrant in 1993. Murphy admired Hani who, she found, was a fearless anti-racist, almost as popularly beloved and respected as Nelson Mandela himself.

She also added a Chris Hani T-shirt to her meagre, androgynous cycling wardrobe, which, with her athletic physique, short hair and lack of make-up, caused some people to mistake her, at first glance, for a man. Red-neck Afrikaners with beer-bellies did not warm to her and her liberal socialist opinions. There were evenings when she had to move several barstools away.

The book was written in diary form, for publication. There has been no retrospective editing to eliminate inconsistencies as her opinions changed. Much of it is engagingly informal. She has a painter's eye for landscapes and skies, a caricaturist's way of sketching men and women she doesn't like. There are repetitious passages of acerbic preachiness. The most dramatic episodes occur off-stage, so to speak, when she trips over a cat at home between journeys and breaks some bones, and when, with her left elbow incompletely healed and without a visa, she has to climb a smuggler's mountainous trail into Mozambique to visit her daughter Rachel.

In spite of all the evils she observed in South Africa, her final overall impression justifies what diplomats call "cautious optimism". She writes:

This country is healthily thirsty for freedom of information and freedom of speech, liberties abhorred and outlawed by the old regime. Nowadays bureaucratic inefficiency is exposed. Educational chaos is exposed. Racial discrimination is exposed. Diplomatic ineptitude is exposed. Political cupidity is exposed. Regularly dirty linen is washed openly on the riverside of public opinion.

Dervla Murphy is said to be bicycling around Ireland now, perhaps heading your way, to write another critical travelogue. It must be said that she is obviously one tough cookie - whose heart is in the right place.

Patrick Skene Catling is a novelist and critic