THE MARATHON BY BICYCLE: THERE ARE nine million bicycles in Beijing, and I was having a hard time finding just the one.

Like being lost in an ocean without a drop to drink. The thought of actually stealing one did cross my mind before I made one last inquiry at the Hotel Tibet.

"You want rent bicycle?" the Olympic volunteer asked and led me around the back toward a mountain of bicycles all seemingly locked together. He pulled one out from the side: "Bicycle!"

Like many people, I was under the impression the bicycle was the best way to get around Beijing. It is - if you're willing to risk life, limb and a nervous breakdown.

Just 50 metres from the Hotel Tibet I was starting to wonder if cycling the Olympic marathon route was really a good idea. Had I taken out travel insurance coming here?

But there's a pleasant breeze blowing and it's the coolest morning in Beijing all week as I head off in search of Tiananmen Square and the thin blue line that marks the 26.2-mile route - along which early tomorrow morning Paula Radcliffe hopes to finally realise her Olympic dream.

The first rule of cycling in Beijing is that there are no rules. It's organised chaos. There are bicycle lanes on every street and there's no running order. Just hold your line. Don't panic. It's operation freeflow with the emphasis on free.

Beijing is one great bicycle circus: bicycles piled-up with cardboard boxes, loaded with rolled-up mattresses, with dogs on handlebars; old ladies on big bicycles; small men on three-wheelers; foldable and rusted bicycles.

I soon realised not one us was wearing a helmet. Every approach to traffic-lights was like a bunch sprint in the Tour de France. Buses drive at you instead of beside you - it appears the bicycle never has the right of way.

But once you get used to this, the bicycle is the best way to get around Beijing.

During the city's first building boom - 600 years before the current one - Beijing was laid out symmetrically on a north-south axis. In the centre is the former imperial residence of the Forbidden City. North is Jingshan Park, where the last Ming emperor is said to have hanged himself, and beyond that the Bell Tower, which for centuries told Beijingers the time.

In 1958, when the Communists expanded Tiananmen Square at the southern gate of the Forbidden City, they placed the Monument to the People's Heroes on the same axis, in the centre of the square. It's here, the city's most symbolic location, the marathon route begins.

It's symbolic too that Beijing chose the 28-acre site at the top of the north-south axis to build its Olympic Green, underlining the importance of the venue. It's 10 miles north as the crow flies from Tiananmen, yet the marathon, naturally, takes the scenic route.

On leaving the square, the race first heads east, then south toward the Temple of Heaven, the largest altar in China, covering a massive 273 hectares. It's just three miles into the race, but some runners will likely say a quick prayer.

Truth is I didn't go this way. Clouds were gathering over the dense Beijing skyline, and with the obvious threat of rain, I needed to take a short cut. So I effectively skipped the first 10 miles of the course and rejoined it as it returns through Tiananmen and turns west towards the new National Grand Theatre, a seriously impressive structure.

After returning north, the course swings west again, out past Beijing Zoo, Zizhuyuan Park, and up towards Peking University.

Okay, so I skipped this part as well. It started to spit rain and my bicycle was actually in rag order. The handlebars shook, the chain creaked; I felt like dumping it at one of the bicycle graveyards you find next to most metro stations.

I'd have taken the metro or even a taxi if I had not been so determined to at least make it to the marathon finish. So I followed the slipstream of cyclists heading north for what felt like an hour, breathing in vast volumes of God knows what before rejoining the thin blue line of the course as it crosses the Fourth Ring Road and heads for the Olympic Green.

Here, all roads are shut off to traffic, and I could almost freewheel the last mile or so up toward the Bird's Nest. It's a spectacular climax to what will surely be a brutally tough race, particularly with the heavy heat set to return this weekend.

I felt I deserved to cycle a lap of the stadium as just reward for my efforts, but the armed guards at the gate were having none of it.

Back at the Hotel Tibet, I returned the bicycle to the Olympic volunteer and said, "Thanks a lot." It was only when walking away I noticed how badly my legs were wobbling, and I couldn't tell if this had resulted from the exertion of the ride or just the sheer terror of it.