At 4,551 metres, Kunzum Pass is the gate between two worlds. On one side lies Lahaul, with the Chandra river and the green fringes of the Himalayan monsoon. On the other side lies Spiti, a high, dry cold desert where the mountains are bare and brown, the sky is absurdly blue, and villages sit in oases on the valley floor. The pass is the only road link between the two valleys, and it is closed by snow for much of the year, usually opening around June and shutting again by October or earlier.
At the top, there is a small shrine to Kunzum Mata, a local deity, with a cairn of stones and strings of prayer flags snapping in the wind. Riders and drivers traditionally circle it clockwise before going on, and it feels right to do it. The view across the glaciers and peaks of the Lahaul range is enormous, and the air is thin enough that even a short walk makes you breathe hard. Chandra Taal, a lake shaped like a crescent moon, is a short and rough detour from the road near the pass, and is one of the high points of any trip in this region.
The riding is demanding rather than technical. On the Lahaul side, the road climbs in a series of hairpins on a surface that varies from broken tarmac to loose stone, with streams that run across it and can be deep in the afternoon when the snow melts. The descent toward Losar is broad and bumpy. Landslides and stalled trucks can hold things up. Altitude sickness is a real risk if you have come up fast, so take a day to acclimatise, drink water and be willing to turn back.
Kaza, in Spiti, and Keylong or Tandi, on the Lahaul side, are where to fill up, and it is sensible to carry a reserve. Start early, because the water crossings are easier in the morning, and keep an eye on the weather.