The fastest time to cycle 100 miles (160.93 km) on a tandem bicycle (mixed) is 5 hours 22 minutes 37 seconds, achieved by Lady JB Owen and Peter Giesin on the certified Moffat–Mosca road course along Colorado Highway 17, Colorado, USA, on 26 September 2026. They averaged 29.93 km/h (18.60 mph) on a steel touring tandem with no aerodynamic equipment, despite around 50 km of dense fog and strengthening winds. The record was officiated and ratified by the World UltraCycling Association (WUCA).