According to Official Guinness Records,
The fastest speed in a human-powered vehicle by a woman is 121.81 km/h (75.69 mph) and was achieved by Barbara Buatois (France) on a flat road surface pedalling the streamlined recumbent bicycle Varna Tempest at the World Human Powered Speed Challenge 2010 near Battle Mountain, Nevada, USA, on 15 September 2010.
For a complete list of 2010 records, please visit 2010 Guinness Records in United States.