Tour de France : speed at all costs

areppim chart of average speeds of the Tour de France since 1903.The average speed attained by the winners of the Tour de France increased by 55.6% since the first race in 1903 through 2015. This means an average speed increase rate of 0.44% each Tour.

Speeds of Tour de France: always faster, but how much is this the result of doping drugs? (Tour de France speeds, and Doping tarnishes cycling performances).