Training by power? FTP and zones Printable zones card
Long ride? Carbs and fluid per hour
Work is exact: average watts × seconds ÷ 1000. Calories are an estimate: kJ ÷ 4.184 ÷ efficiency. Riders turn roughly 20–25% of food energy into work and 1 ÷ 4.184 is 23.9%, so 1 kJ of work is close to 1 kcal burned. Sources: NIST (1 kcal = 4.184 kJ); TrainingPeaks, CTS and TrainerRoad (efficiency range, 1:1 rule); Hopker et al., 2010 (measured in trained cyclists).