Perched on the edge of a narrow gravel road with a helmet strapped on my head, I start to think I have made a horrible mistake.
To my left, a sheer 1000m drop into the valley below.
In front a slip has wiped out much of the already narrow pathway.
"Is it too late to change my mind?" I ask the tour guide.
"Yip."
The short, confident reply seals my fate.
And so we're off - a group of gringos (foreigners) on mountain bikes adorned in fluoro orange safety vests racing their way down the World's Most Dangerous Road.
The name was given to the 60km-70km route between Bolivian capital La Paz and popular weekend getaway Coroico by the Inter-American Development Bank in 1995.
It is affectionately known by locals as El Camino de la Muerte (Death Road).
A new road connecting La Paz and Coroico was completed in 2006.
Most traffic now uses that one, leaving the old route to the hundreds of tourists who pay to bike down it daily.
When it was the main highway, the annual road toll for Death Road was believed to be more than 300, a little below that for the whole of New Zealand (350-400) in the past few years.
We had been in La Paz for less than two hours before we were in the Gravity offices booking a tour for the next day.
The company has a reputation for offering the safest, most organised tour of Death Road.
New Zealander Alistair Matthew started the company more than a decade ago and continues to run it as owner/operator.
Bored with an office job in Wellington, he headed overseas for adventure and saw a unique opportunity to turn his love for bikes into a business.
Gravity was the first company to commercialise tours on Death Road.
Luckily for us, Mr Matthew was one of the guides for our tour.
With his long beard, tattoos and laid-back attitude, it is hard to imagine him behind a desk.
The tour began at a coffee shop in La Paz.
A roll-call is taken and the dozen people in our group pile into a van.
An hour later, we arrived at La Cumbre, 4700m above sea level.
Even the fittest were feeling the effects of high altitude.
We were given bikes, helmets, safety vests, pants, jackets and gloves.
Weighing 5kg more and wobbling around atop a bike for the first time in years, we practised on a stretch of paved road.
To appease the gods we sipped a foul-tasting alcohol and poured a little on the front wheel of the bikes.
I wasn't convinced about this preventing accidents but the look on everyone's faces when they tasted the drink was much-needed comic relief.
Then the questions started.
Has anyone ever died doing this? Yes.
Only one with Gravity - a middle-aged American man crashed and fell off a cliff.
No-one was near him and it remains a mystery why he crashed.
There is another common tale among travellers, about a woman who rode off the edge of the cliff, and kept pedalling in mid-air.
Mr Matthew told us the story was partly true.
She was pulling into a rest stop with the rest of her tour group and her brakes failed and she went over the cliff.
Her story highlights one of the major dangers of the road - unsafe tours.
In the 10 years since Gravity started, numerous other tour groups have sprung up.
Some are OK, but others have little regard for safety.
It pays to check out any company and their bikes before handing over cash.
After riding through a drug checkpoint (ironic for a country where the production of coca leaves, the raw ingredient in cocaine, is an economic staple), there is a slight uphill section before the real Death Road begins.
It is unpaved, narrow, windy and steep.
And that's without mentioning the dramatic cliff along one side.
Following heavy rain there had been several serious slips on the road.
The van is unable to follow us down and we are on our own without some of the safety gear or the option to sit out sections of the ride.
It is then we realise the seriousness of what we have signed up to.
With no other option, we lift our bikes on to our shoulders and begin trudging through a section of washed-out road.
A waterfall cascades over our heads as we sink knee-deep in mud and debris.
It is actually quite fun. The ride takes more than five hours.
There are regular stops for water, food, photos and safety information.
We have to ride longer than normal because the van can not get in to meet us at the bottom of the road.
By the end of the day we are down to 1000m above sea level.
We are hot, tired, dirty and feel extremely smug having survived the trip without serious injury.
A few came off their bikes and there were those who had cramp in the fingers from gripping the brakes.
But, overall, we were unharmed and happy to have escaped the clutches of Death Road.
