Idly browsing some retro stuff, I came across a few discussions on medium gear time trials. All of this is well before my time, but Mr I Snr tells that, in the days of steel and toeclips, some time trials were restricted to 'medium' gears - that is, less than 72", or about 48x18. Fixed of course. Anyway, I found this report of what appears to be the first sub-hour medium gear 25. In the 1950s all courses were slightly downhill and all winds were tailwinds , but spinning at nearly 120rpm for 25 miles is still pretty impressive.
Oh, and you don't need to go far down the results list to find our President's late husband. Classy rider indeed.
[url]http://www.fixedwheel.co.uk/medium%20gear%20history.htm[/url]