Peter Post has (I think) the second fastest time at just over 45 kmh in 1964. It was a very different race back then, for starters it actually ran from Paris to Roubaix! It was cobbled because at that time even the main roads were cobbled although these were "normal cobbles", As roads were resurfaced in the late 60ies and 70ies they had to find secteurs where ever they could and these were rougher agricultural tracks or in the case of Arenberg an access road to a mine. So yes,, you still had to be tough as hell to win, especially at those speeds in the 60ies , but not in the same way as today.I think it's amazing that Pino Cerami rode a PX10 to victory at the 1960 edition of the Paris Roubaix and it stands as the 7th fastest ever..either he had balls of steel or his secret weapon was a Brooks.!?