Menstruation: Cycling’s missing metric

August 27, 2026

Cycling is awash in metrics – power output, watts per kilogram, heart rate, cadence, nutrition to the gram. The marginal gains culture that transformed men’s professional cycling has arrived in the women’s peloton, and the data obsession has come with it. And yet, there is a very significant physiological variable that affects all 147 riders in the Tour de France Femmes which largely goes unaccounted for. And it’s not because we don’t know enough about it, but because the sport has yet to decide whether it’s worth knowing. escape