What peak speed in km/h did Usain Bolt reach during his 2009 100 m world record? (50 km/h ≈ 31 mph)

Answer

44.7 km/h

Bolt hit 44.72 km/h between the 60 m and 80 m marks of his 9.58-second run in Berlin — well above the 30 km/h speed limits now common in city centers. No human has been reliably measured going faster on foot.

Source: IAAF Biomechanical Research Project, Berlin 2009