Just been reading on "time trial forum" about the late Beryl Burton's 12 hour record set in 1967, on a steel bike with no air cheating gadgets, total distance 277 miles, which broke the ladies record at the time. To put things into perspective Mike McNamara broke the Men's record the same day with a total of 276. Was this the best performance of all time. Beryl's average speed 23 MPH.