"So what we're gonna do now is one of the most important safety techniques in Bolivia," says Matthew as he unscrews the cap on a small plastic bottle. "We're gonna share a little bit of a blessing with Pachamama who is the Bolivian earth goddess."
He takes a swig and pours a splash on the ground. He instructs all of us to do the same.
"Pachamama's gonna be happy with us," adds Matthew. "She's not going to need a blood sacrifice today."
He smiles. I take a swig and wince. Nothing like a little rubbing alcohol to get you going.
The ride begins gently enough. We will cover 60 miles and drop from almost 16,000 feet above sea level to 5,000 feet, traveling from the high planes of the Andes through the clouds to the subtropical jungles that lead to the Amazon. The first 15 miles are paved, which gives us all a chance to get used to the bikes and the terrain and the traffic. Trucks and cars barrel past us, but with the steep mountain road in our favor, we zip past the slower vehicles.
It is not the kind of day they show you in the travel brochures: We are cycling through dense fog, cold sleet and pelting rain on a wet slippery road. The thin air means it takes a huge amount of effort just to catch your breath.
Even going downhill is hard work.
Thankfully, there are regular stops, giving the laggards a chance to catch up and Matthew a chance to brief us on the adventures ahead.
"The bad news is we're at 11,400 feet above sea level here, which means there's very little oxygen," he says. "You are gonna find it tough on this section, it's about 3 miles, 3½ miles of pedaling mostly uphill."
Some bikers opted for a free ride uphill aboard the bus, but most came here to push the limits, and that's exactly what this grueling stretch of road does. Human legs were not designed to pedal bikes at this altitude. The muscles in my legs scream for oxygen as I inch up the hills.
For Stuttard -- or her legs -- it was too much. I pass her as she is walking her bike up the hill.
"There was no oxygen in the air," she tells me at the summit. "I just couldn't breathe. I was really, really tired. I had to get off my bike and walk."
But she hasn't lost her sense of humor. "Shame," she says in her English accent with a little smile. There is no shame. This about testing limits.
The fun part ends with the pavement. We turn off onto a narrow, rutted road and stop for another briefing.
"Just around the corner, it's going to get one-third as wide, a little bit bumpier, slipperier and muddier," warns Matthew. "And the really good news is, off to our left, there will be anything from a 300 foot to about a 1,000 foot parachuting option for the next 42 kilometers or 30 miles."
There's that irony again. But we have to take him at him at his word. The thick fog obscures our view of the treacherous drop. All we can see is the pelting rain and the road covered in a muddy slime.
"The good news is that because the drop is on the left-hand side, we get to ride on the left-hand side. We affectionately call it the scenic side," says Matthew as he instructs us to suppress our instinct to cling to the safe side of the road when we encounter cars. "The reason we ride on that side is because all of the vehicles have their steering wheel on the left-hand side. The road is so narrow that the driver has to be able to stick his head out the window to make sure the wheels are on the road."