The rear derailleur was banned in the Tour de France until 1937. The winner in 1936 was Sylvère Maes, from Belgium, he completed the 4438km route in 142h 47' 32" (31.072km/h)
Only 10km/h slower than the 2003 Tour's average. not bad for only having one gear, well, one gear at a time. You had to take the rear wheel off and flip it over to get the other gear.