Furka, Grimsel and Susten: Hauptstrasse 19, 6 and 11, Switzerland

Distance: 120 km (75 miles) loop from Andermatt, with 3,600 m (11,800 ft) of climbing. One long day. Altitude: 2,429 m (7,969 ft) at Furka Hairpins: 25 across the Furka alone, 15 on the Realp ramp and 10 on the Gletsch side Key passes: Furka (2,429 m), Susten (2,224 m), Grimsel (2,164 m) Best for: technical passes, one-day loops, engineering Best time: mid-June to mid-October Technicality: High on the Furka, moderate on the Grimsel, deceptively easy on the Susten.