- Guy Martin
- 137.78 kilometre(s) per hour
- France (Mont Ventoux)
The fastest speed in a soapbox is 137.78 km/h (85.61 mph) and was achieved by Guy Martin (UK) at Mont Venoux, France, on 16 October 2014.
The run was made down a 2 km stretch of road, and was the fastest of five attempts.