Mick Butler wrote: "Probably not but in the case of the " Hell of the North" Paris-Roubaix definitely yes. In the 1964 event Peter Post rode the event at a speed of 45.129 kph or 28.042 mph. I think this record still stands or it did in 1994, someone will correct me if its wrong. Think the fastest Ruban Jaune (yellow ribbon) was by the Italian Vigna in the 1964 Three Varesine Valleys at 47.17kph or 29.311 mph. But the record that we all remember here in Europe is Freddy Maertans 1975 Paris-Brussels at 46.11kph or 28.651mph. Our own Sean Yates held the record for the fastest stage win in the Tour de France for many years."
Peter Post's record average speed for P-R still stands. Second is Rik Van Steenbergen at 43.970 kph in 1948, and third Pino Cerami at 43.538 kph in 1960.
Post, who was also one of the greatest 6-day racers, won in a four-man sprint. One of the other riders was Benoni Beheyt. I recall reading that conditions were favorable, with a wind blowing from the south. The course in 1964 didn't have some of the toughest cobbled stretches used today, like the Arenberg forest. It is an incredible speed, nonetheless, and incredible that the Ruban Jaune could have been taken in P-R, and held for 11 years without the record being broken in Paris-Tours during that time.
One can imagine the awful state of the roads after the war in 1948, so Van Steenbergen's speed is also amazing.
The Ruban Jaune history can be found here: http://townsleyb.members.beeb.net/procycle/YellowR1.htm. The current holder of the record is Andre Tchmil, according to the list.