How many calories does a Tour de France rider burn on a mountain stage?

How to get close to this number

Scale from a normal day. A sedentary adult burns a couple of thousand calories doing nothing in particular; several hours of sustained hard effort on a bicycle can easily triple that. The explanation states the multiple directly, and reasoning as a multiple of a baseline you know is far more reliable than estimating an athlete's output in absolute terms.

What people miss is that eating becomes the constraint. Burning six thousand calories is achievable; consuming six thousand while your digestive system is competing with your legs for blood supply is genuinely hard, which is why teams employ chefs and why riders eat during the race itself. In extreme endurance events the limiting factor is usually intake, not output.

This figure describes a hard mountain stage, not an average day of the race. Flat transitional stages are far lower, and a rest day lower again, so quoting one number for "a Tour rider" without the stage type attached is misleading. The figures also come from team nutrition staff rather than from independent measurement, which makes them credible estimates rather than laboratory values.