Source for statistics from pro cycle races
Depending on what you're looking for, a site like trainingpeaks.com might meet your needs. You can often find power meter data files for riders collected during both the Grand Tours (the Tour de France, the Giro d'Italia, and the Vuelta a Espana) as well as many one-day classics (like the Ronde van Vlaanderen (the Tour of Flanders) or Paris-Roubaix). From these data you can extract speed, power, cadence, gear ratios, pedal force, heart rate, and slope over different segments of a race. In certain circumstances you can estimate aerodynamic drag and other parameters of performance.