Bolivia boasts a number of record statistics. At 3,660m, La Paz is the highest de facto capital city in the world (Sucre is the official capital), and Lake Titicaca, at 3,811m, is the highest navigable lake.
Within the context of cycling, the Alto Irpavi velodrome in La Paz, at 3,417m, is the highest and fastest in the world, and the venue for Arnaud Tournant's 2001's kilometre record of 58.875 seconds, which Chris Hoy missed by the narrowest of margins in 2007 on the same track.
And the Vuelta a Bolivia features the highest stage in the UCI road race calendar: at 4,496m above sea level, La Cumbre towers the best part of 2,000m above its nearest European rival.
Gregorio Ladino, last year's winner, explains its effect. "The heat is OK - it's normal for us. But it's twice the altitude of Colombia here. The lack of oxygen just makes it incredibly hard."
As altitude increases, air pressure decreases and, with it, the amount of oxygen. So, at 2,500m, roughly the highest point in the Tour de France, there is 25 per cent less oxygen than at sea level.
At 4,500m, this decreases further to 59 per cent, a deficit which, unless you are used to it, is going to stop you in your tracks. Fredy Gonzáles, two-time winner of the Giro d'Italia's king of the mountains competition, gives his verdict: "It's very, very hard to ride at this altitude if you don't have the conditioning or experience. It's totally different. You're giving 100 per cent and the bike just doesn't respond. I think you can take three or four minutes out of other riders when, at a normal altitude, it would be maybe 30 seconds or a minute."
Today's start lies at 3,815m, and the sun bears down on the teams as they make their preparations. A group of young boys look on from a ledge above the road. We're in the highlands now, and their clothes show it: the thick jackets and tall hats they are wearing are typical of the region.
Some of the Chilean riders pose for photos with them. It's a harsher, more barren place; the air is dry and thin. La Cumbre looms 60km down the road and more than 600m higher, but with an 80km flat run in to the finish, it's unlikely any one rider will be able to survive alone.
Once again, there is no doubting what the local wonder has planned for the day. Soliz sets about distancing himself from the peloton with a devastating attack at the base of the first of the stage's three climbs.
Boyaca's Mauricio Neysa and Bolivian Juan Cotumba follow in dogged pursuit as they reach the final climb to La Cumbre, but the aptly named "Volcano" is in his element, flying up this beast of a mountain like it was just another hill.
I jump out of the car at the summit and scramble up the ridge above the road to find a vantage point for some pictures, and I'm still gasping for breath several minutes later as Soliz cruises into view.
Another minute or so and the first group appears, but the rest of the riders are spread out as far as the eye can see and beyond. As the last of them finally come past, I run down and grab a lift in the broom wagon.
Two of the Chileans have abandoned and sit opposite me, dazed and exhausted. One of them, Carlos Miranda, stood on the podium the day before in third place.
"It's just too hard - we're not designed for this" he grins, resigned to the fact that they are in terrain which truly is beyond them. Another casualty is the winner of stage three, Serbian Zsolt Der. Suffering with bruises from a crash the day before, he is disqualified for holding onto his team car. The European contingent is now down to only one.
At the finish in Oruro, a desolate mining town famed for its masked carnival, Soliz is pipped on the line by Colombian Neysa, who along with local rider Cotumba, managed to haul him back on the long run in.
The army band strikes up another tune, out of place in the wide-open expanses of the desert at Vila Vila. The sixth stage runs 162km from here to El Alto, which sits on the high plains above La Paz, at 4,111m.
As the race returns to the region with the longest heritage and greatest interest in the sport, the Bolivians are eager to win - and they do. The first five riders are all locals, led home by Jorge Quispe of the Pio Rico team through streets lined deep with enthusiastic spectators.
It's a marked difference from the early stages in Santa Cruz where the locals looked on in bemused curiosity, unfamiliar with the ways of professional cycle racing. Here, in one of the poorest cities in Bolivia, perched on the plain above La Paz, colourful crowds throng the route from the outskirts to the finish, waving flags and cheering their support as the riders race by.
This is an extract from Rouleur issue 22.