The Ofenpass, which the Romansh call Pass dal Fuorn, climbs through the only national park in Switzerland. The park was founded in 1914 and the road is the single way to see it by bike, so the rules matter: stay on the road, stop only where parking is allowed, and leave the ibex, red deer and marmots to their own devices.
From Zernez in the Engadine the road rises through Scots pine and then mountain pine into a high, open valley, with the peaks of the park rising on either side. Bends are generally moderate and the road is wide, in good shape, and rarely crowded. On the far side it drops through the Val Müstair, towards the Italian border at Tubre, a quiet, pastoral valley with Romansh villages and terraced fields. Ibex and red deer graze at the roadside in the early morning and evening, so slow down when you see animals.
Müstair, at the bottom of the descent, has the Benedictine convent of St John, a UNESCO World Heritage Site that contains one of the best-preserved sets of early medieval frescoes in Europe, dating back to about the ninth century. It is worth the extra kilometres. Further on, the Stelvio pass climbs from the Italian side, a very different and far more famous road, with dozens of hairpins and many visitors.
Fuel is available at Zernez, but not within the park, so make sure the tank is full before you start. The pass is open all year round in normal conditions, though snow can close it for short periods in winter. Summer thunderstorms build in the afternoon, and the temperature changes quickly, so dress in layers. Mobile coverage is thin, and nobody will hear you if you break down, so carry what you need.