The young Ernesto Guevara was footloose and fancied free travel. Simon Calder introduces an extract from a new biography of Che; Che's long and winding road to revolution
There he is, that familiar figure gazing out heroically from beneath his trademark beret in the general direction of immortality. "Hasta la Victoria Siempre" reads the equally familiar slogan, "Always towards victory".

You don't have to be dead to be a Cuban hero, but it helps. Fidel Castro, living proof of the triumph of ideological optimism over grim reality, gets only two graven images on the entire island. In contrast, Ernesto "Che" Guevara is everywhere, as much a part of Cuba's political scenery as the face of Jose Mart, the father of Cuban independence.

Cuban history has absolved him. Yet Che was never the son, prodigal or otherwise, of his adopted nation. He was an Argentinian cousin, often distant, who served his revolutionary apprenticeship on the high roads and in the low dives of Latin America - a rebel with a cause.

The catalyst for his first great expedition may have been his sweetheart "Chichina" - Mara del Carmen Ferreyra. A beautiful heiress, she had refused his proposal of marriage and the promise of a trip around South America. Instead, the 23-year-old Ernesto set off with a close friend, Alberto Granado, six years his senior. Their transport was La Poderosa ("the powerful one"), Alberto's nickname for his doddery old 500cc Norton motorcycle.

On 14 January 1952 they embarked from the beach resort of Miramar on a journey that was to be far from heroic. Ernesto's father, Guevara Lynch, provided a revolver that was to prove an unhappy introduction to ballistics. As this extract from a monumental new biography (reviewed below) shows, the two travellers veered between feckless guile and reckless guilt on their rampage around the continent. Part of this adventure is chronicled in Che's own's journal, Notas de Viaje. But his biographer, Jon Lee Anderson, also spent three months in Argentina in 1994, much of it in the company of Che's travelling companion, Alberto.

In death, the name of Che - like that of Christ - has been invoked to serve a multitude of motives.However, Anderson says, "My sole loyalty in this book is to Che Guevara himself; to write what I perceive to be his truth, not anyone else's."

The road was clear to begin their great trek, and the two gypsies sped off. It took them four more weeks, however, to leave Argentina. Before they were halfway across the settled pampa west of Bahia Blanca, Ernesto succumbed to fever and had to be hospitalised for several days; then they returned to the dust and pound of the trail.

By the time they reached the picturesque Lake District in the forested eastern slopes of the Andean cordillera, bordering Chile, their meagre revenues had dwindled, and the two were becoming expert freeloaders, or mangueros motorizados (motorised scroungers), as Ernesto wryly defined it. It became a contest between Ernesto and Alberto to see who could outdo the other in the art of grubbing for survival.

Sometimes, rejected by their prospective hosts, they were forced to pitch their tent. But more often than not, they were successful, finding floor space for their cots in garages, kitchens, barns, and frequently police stations, where they shared cells and meals with an interesting variety of criminals.

Staying for a night in the barn of an Austrian family, Ernesto awoke to hear scratching and growling at the barn door, and saw a pair of glowing eyes peering in. Having been warned about the fierce local "Chilean pumas" he aimed the Smith & Wesson that Guevara Lynch had given him to take on the journey and fired a single shot. The noises stopped, and he went back to sleep. But in the morning he and Alberto awoke to discover that Ernesto had bagged not a puma, but their hosts' beloved Alsatian dog, Bobby. The two escaped, pushing La Poderosa downhill - for she wouldn't start - followed by their hosts' wails, imprecations, and insults.

In the Lake District, they hiked around lakes, climbed a peak - scaring themselves by nearly falling to their deaths - and used Guevara Lynch's revolver to poach a wild duck. At one particularly scenic lakeside spot they fantasised about returning together to set up a medical research centre.

Back in Bariloche after their jaunt, Ernesto opened a letter from Chichina informing him that she had decided not to wait for him. Outside, a storm raged. "I read and reread the incredible letter. Just like that, all [my] dreams... came crashing down... I began to feel afraid for myself and began to write a weepy letter, but I couldn't, it was useless to try." Outwardly reconciling himself to his loss, Ernesto was determined to enjoy the rest of the journey. Writing about their crossing of the Andes to Chile, Ernesto invoked the lines of a poem that began: "And now I feel my great root floating naked and free..."

Entering Chile, they obtained free passage on a ferry across Lake Esmeralda by manning the bilge pumps of the leaky cargo barge it pulled. Aboard, they met some Chilean doctors, to whom Ernesto and Alberto introduced themselves as "leprologists". The gullible Chileans told them of the Pacific territory of Easter Island, Rapa Nui, where Chile's only leper colony existed alongside hordes of sensuous, pliant women. Hearing this, Ernesto and Alberto immediately extracted a letter of recommendation from their new friends for the "Society of Friends of Easter Island" in Valparaiso, where they might secure free ship passages to the island. By the time they reached dry land, they had resolved to add this exotic new destination to their ambitious itinerary.

Their next stop was the Pacific port of Valdivia, where they paid a visit to the local newspaper, the Correo de Valdivia, and came away with a glowing profile of themselves, published under the headline "Two dedicated Argentine travellers on motorcycle on their way through Valdivia". Not ones to miss a good opportunity, Ernesto and Alberto had solemnly reinvented themselves as "leprosy experts", with "previous research in neighbouring countries" - and the unsuspecting Correo reprinted their claims. In addition to leprology, Ernesto and Alberto must have given free rein to their judgements on a wide variety of topics, for the Correo went on to laud them for having, "during their very short stay in our country, penetrated its social, economic and sanitary problems".

Press clippings in hand, which Ernesto proudly called "the condensation of our audacity", they were off again. A day later, La Poderosa took a fall, smashing her gearbox and snapping part of the the steering. As they repaired her in a workshop in the whistlestop of Lautaro, they became instant celebrities as the locals gathered around to watch. They managed to scrounge a few free meals and, after La Poderosa had been patched up, were invited to drink some wine with their new friends.

Ernesto found the Chilean wine delicious, so much so that by the time he and Alberto arrived at a village dance, he felt "capable of great feats". There, having drunk even more, he invited a married woman to dance and began to lead her outside while her husband watched. The woman tried to resist, Ernesto continued "dragging her", and she fell to the floor. After that, Ernesto and Alberto were chased from the hall by infuriated dancers.

With Ernesto at the helm of La Poderosa, they left town, "fleeing places that were no longer so hospitable to us" but only a few kilometres out of town, at a tight bend in the road, La Poderosa's rear brake failed, and then, as she picked up speed downhill, her hand brake failed as well. Ernesto swerved to avoid a herd of wandering cows, and they crashed into the road bank. Miraculously, La Poderosa was apparently undamaged, and, finding her rear brake once again mysteriously working, they continued their trek. But the day was not yet over.

"Backed up as always by our `press' letter of recommendation, we were put up by some Germans who treated us in a very cordial manner," wrote Ernesto. "During the night I got a colic which I didn't know how to stop; I was ashamed to leave a souvenir in the chamberpot, so I climbed on to the window, and gave up all of my pain to the night and the blackness... The next morning I looked out to see the effect and I saw that two metres below lay a great sheet of zinc where they were sun-drying their peaches: the added spectacle was impressive. We beat it from there."

Leaving a lengthening trail of irate hosts behind them, the two continued their escape to the north, but their faithful steed began to fail them. Every time they reached a hill, La Poderosa balked, and finally gave up. It was their last day as motorised scroungers.

A lorry deposited them and the crippled Poderosa in the next town, Los Angeles. They found lodging in the fire station after chatting up the three daughters of its chief. Later, Ernesto paid coy homage to the uninhibited girls as "exponents of the grace of the Chilean women who, whether pretty or ugly, have a certain something of spontaneity, of freshness, that captivates immediately".

The next day they left on a lorry headed for Santiago, lugging the carcass of La Poderosa with them like the body of a fallen comrade.

Extracted from Che Guevara: A Revolutionary Life by Jon Lee Anderson, published by Bantam Press, price pounds 25. Available from bookshops or by mail order to 01624 675137. All rights reserved.