Abstract After analyzing historic records , El Helou et al. [1] reported a distinctive 6.38% improvement in speed in European professional road racing fro m 1993 onwards, a period wh ich coincides with the years of the ‗epo epidemic' in professional cycling. We aim to show that this improvement might be spurious, since El Helou et al. did not account for the influence of confounding variables on riders' speed progression over time. We scrutinized arch ival data provided by the French Association Mé moire du Cy clism
