Few roads in South America have a signature as clear as this one. Los Caracoles, the snails, are the string of tight hairpins that carry the Chilean side of the Paso Los Libertadores up the last wall of the Andes, switchback upon switchback stacked up the mountain like a dropped ribbon. Locals count them in the high twenties, and every rider you meet will have a different number. At about thirty-two hundred metres, this is where the road gives up its fight with the slope and heads for the tunnel that now carries almost all the traffic into Argentina.
Riding them is a mixture of delight and discipline. The hairpins are tight enough to need first gear, the surface is paved but patched, and on the inside of each turn the camber and the grit are worse than they look. Lorries labour up in low gear and cannot take the bends neatly, so give them space and never overtake on a hairpin. The altitude takes a little power from the engine and a good deal from the rider, so you will feel the thin air in your head before you notice it in the throttle. The reward at each corner is a wider view of the valley below, the road you just climbed visible beneath you, and the peaks standing in the clear air.
The pass has a long human history. This is the route San MartÃn took in 1817 with the Army of the Andes, hauling cannon across the mountains to surprise the Spanish in Chile, one of the great feats of military logistics of the independence era. Before him, mule trains and couriers used it, and in the early twentieth century the railway tunnelled underneath. At the top of the old pass, now reached by a separate road, stands the Cristo Redentor of the Andes, a statue raised in 1904 to mark a peace treaty between Chile and Argentina.
Los Andes is the place to fill up. Dress warmly, even in midsummer, and carry water. Late summer and autumn, after the thaw, give the clearest weather.