You will feel Chivay before you see it, in the lungs. The town stands at about 3,600 metres in the Colca Valley, and anyone who rode up from Arequipa at near sea level on the same day tends to arrive a little dizzy, thick-headed and surprisingly hungry. The road does it to you in stages: out of the desert suburbs, up past the cones of Misti and Chachani, across a bleak plateau of alpaca pasture and vicuña at something close to 4,900 metres, and then down again into a green valley that looks like another country entirely.
Chivay is the valley's working capital rather than a showpiece, a market town of four and a half thousand people with a plaza, a handful of simple hotels and the sort of stalls where women in embroidered hats sell potatoes in a dozen colours. The Collagua people terraced these slopes long before the Incas arrived, and the Spanish later gathered the scattered villages into the neat grid towns you still see, each with a whitewashed church of stone and a Spanish name. The terraces are still farmed. Just outside town are hot springs where you can lower yourself into steaming water with the mountains going pink above you, and that is the right way to spend an evening after the altitude.
The ride is the real subject. The tarmac is generally good, but the pass is long and exposed, with fierce cold, sudden hail and thin air that starves a carburetted engine, so give the bike a moment and yourself more. Further along the valley the road follows the canyon rim toward Cabanaconde, passing the Cruz del Cóndor lookout, where Andean condors ride the morning thermals. Be there early, since the big birds tend to show between about eight and ten.
For practical matters, treat the fuel tank in Arequipa as your main supply and top up whatever you can in Chivay, where small stations serve the valley. Drink plenty of water, go easy on the first night, and try the coca tea, which locals swear by and which at least gives you something warm to hold. Evenings drop close to freezing even in the dry season.