The priest manages a small, inscrutible smile as he clambers on to our bus. "Lord, protect your children on their journey," he said in querulous Spanish, making a long sign of the cross over our heads. "If it be Your will, help them reach their destination." Then he sets off again.
It's not exactly a vote of confidence, but then the World's Most Dangerous Road hardly merits one. This land-based equivalent of the Bermuda Triangle has been awarded its title by the Inter-American Development Bank in 1995 after 26 vehicles plunged from its barrierless, veritgo-inducing ledges in 12 months. Unfortunately, the road from La Paz to Coroico, a charming village on the other side of the Cordillera Real mountain range, still provides the only access to the fertile and impossibly hilly Yungas region.
In the absence of funding to erect barriers, Bolivians pragmatically enlist the help of any deity available before setting off. As we grind up the approach road from La Paz, our driver thoughtfully recruits Pachamama, or Mother Earth, on our behalf. With his foot still on the accelerator, he half-leans out of his window and squirts the customary offering of neat alcohol from the plastic bottle, aiming for the front tires.
I prefer my tires to have tread on them, which is why I'm about to get off to do the main 40-mile stretch by mountain bike. It was the poster in our hotel that swung it. "Gravity Assisted Mountain Biking," it read. "It's downhill all the way!" For a determined non-athlete such as myself, there was a certain allure about freewheeling so far downhill. "And if you're going to die, at least you get to steer yourself," adds a lanky Yorkshireman, as 15 of us unload our hired bikes from the bus and strap on helmets.
La Cumbre, the menacing and wind-harried starting point for our journey, is cloud-bound at 15,500 feet, the ice air thin and hard to breathe. "In the next five hours," says Alistair, our New Zealand guide, "we will descend nearly 12,000 feet in to steaming sub-tropical jungle." "A few pieces of advice," he adds, as we prepare to go. "Check your brakes regularly. Yell if you're overtaking someone... And whatever you do, keep your eyes on the road, or you'll be airborne in no time."
The first eight miles are easy. A wide, tarmacked road leads us snaking down the sides of rocky valleys. Buses occasionally roar past, honking in clouds of black exhaust fumes, full of incredulous Aymara villagers shaking their heads or laughing darkly. The slopes below us, only occasionally visible through holes in the clouds, are steep but grassy, dotted with the odd llama or simple wood dwellings, vaguely alpine. It's easy to pick up speeds of 30 to 40 mph on this coasting stretch. I find myself whizzing along numb-faced with my brother Mark, close to the front. We are beginning to feel invincible when the tarmac runs out.
At first I'm too busy trying to steer my juddering bike round crater-like potholes and vindictive dogs to notice the crosses. But as the road narrows and steepens, these simple memorials become too regular to ignore. They sprout in terrifying clusters at sharp corners, and form the only barrier or caution sign between us and oblivion.
In 1983, a lorry driver, Carlos Inde, set a macabre record by veering over the precipice, killing himself and 100 locals crammed into the back of his truck. Last Christmas eight Israeli and two Dutch backpackers plunged to their deaths in a rented jeep. We stop our bikes at a red plastic flag marking one of the most recent accidents and peer over. Nearly 3,000 feet below, half obscured by the foliage and wisps of cloud, lies the flattened cab of a lorry, toy-sized from this height. I feel suddenly dizzy and step back.
CUT TO THE CHASE: Show me the photo slideshow of the World's Most Dangerous Road!!!
It's not hard to see why accidents happen. Much of the road is blasted into the side of the sheer cliff faces, and large parts of it aren't even wide enough for two vehicles to pass. Until last year, one vehicle had to back up, often inches from the edge of the road, to allow the other to squeeze past.
(Note: This system has been removed, the La Paz to Coroico road is now pretty much devoid of traffic for the "dangerous" part, as the new road has been opened and most traffic takes that) The government has introduced a 1-way system by which downhill travel is in the morning, and uphill traffic travels after 5 pm. Although this has reduced collisions, it has increased the average speed on the road as freight drivers rush against the clock. Add this to the constant problem of drivers nodding off, and drunk driving around festival time, and this is still South America's most notorious white-knuckle ride.
As the road narrows and greenery grows ever more lush, I find myself cycling through a waterfall. I veer outwards to avoid a stream running down the center of the road. Almost instantly I am inches from the edge and looking down on clouds. I am just wobbling back to the center of the road when my brother Mark hares past, whooping like a maniac. A lorry follows, coating me in dust.
I spend the next mile angrily catching up, until I see Mark's red bike jolt suddenly and his figure cartwheel over the handlebars. When I arrive he is crawling from the middle of the road, with blood spreading from a scratch on his forehead. "Want to go the rest of the way in the support bus?" Asks Alistair, after testing him for a concussion. Mark takes a look at the bus, which has just pulled up behind us, rattling worryingly. He mops his brow, straightens his handlebars and pedals off, rather more slowly this time. Around the next corner, we finally glimpse our destination. After hours of clenched muscles and rattling teeth, we see Coroico, a small town of white adobe houses perched on a sunlit hillside; it has the aura of the Promised Land. For a further hour we hairpin down the sides of forested valleys, cheered by local children who point and giggle as we scud through the roadside settlement of shacks.
We are, admittedly, a comic spectacle. We shudder to a halt with our panda faces, splattered with water, earth and dust which has baked to a crust, leaving only the white shape covered by our sunglasses.
Crawling on to the bus for the 4-mile uphill road into Coroico, we reflect on our journey through a haze of exhaust and exhaustion. In five hours we have descended nearly 12,000 feet through three different climates and several stages of purgatory. By the time we hobble on to the hotel terrace with a cold beer that afternoon, we will have almost certainly convinced ourselves that we enjoyed every minute.