Imagine you start pedaling at the start of Stage 12 of this year’s Tour de France. Your first task will be to bike approximately 20.6 miles (33.2 km) to the summit of Col du Galibier in the French Alps, achieving an altitude of about 4,281 feet (1,305 m). But this is only the first of three big climbs in your day. You then head to the summit of Col de la Croix de Fer and then finish the 102.6-mile (165.1-km) step with 21 serpentine turns on the famous Alpe d’Huez climb.
On the most opportune day of my life, I probably won’t even be able to complete Stage 12 – much less do it in anything close to the five hours or so it would take for a winner to finish the ride. And Stage 12 is just one of 21 stages that must be completed within 24 days of the tour.
I’m a sports physicist, and I’ve modeled the Tour de France for nearly two decades using terrain data—like the one I described for Step 12—and the laws of physics. But I still can’t fathom the physical abilities needed to complete the world’s most famous bike race. Only a few elite humans are able to complete the Tour de France stage in a time that is measured in hours rather than days. They are capable of doing what the rest of us can only dream of that these athletes can produce an enormous amount of power. Power is the rate at which cyclists burn energy and the energy they burn comes from the food they eat. And during the Tour de France, the winning cyclist will burn the equivalent of about 210 Big Macs.
Cycling is a game of Watts
To ride a bicycle, the Tour de France rider transfers energy from their muscles through the bicycle and to the wheels pushing back on the ground. The faster a rider can pump out energy, the more power. This rate of energy transfer is often measured in watts. Tour de France cyclists are capable of generating enormous amounts of power for incredibly long periods of time compared to most people.
For about 20 minutes, a fit recreational cyclist can apply 250 watts to 300 watts continuously. Tour de France cyclists can produce over 400 watts for the same time period. These pros are also capable of hitting 1,000 watts for a short amount of time on a steep climb—almost enough power to run a microwave oven.
But whatever energy a Tour de France cyclist puts into his bike is converted into forward motion. Cyclists fight air resistance and friction losses between their wheels and the road. They are helped by gravity on the slopes but during the climb they have to fight gravity.
I incorporate all the physics involved in my model with cyclist power output as well as the effects of gravity, air resistance and friction. Using all of that, I estimate that a typical Tour de France winner needs to put out an average of about 325 watts over the roughly 80 hours of a race. Remember that most recreational cyclists would be happy if they could only produce 300 watts for 20 minutes!
convert food into miles
So where do these cyclists get all this energy? Food, of course!
But your muscles, like any machine, can’t convert 100 percent of food energy directly into energy production—muscles can be 2 percent efficient when used for activities like swimming and 40 percent efficient at cardio. In my model, I use an average efficiency of 20 percent. Knowing this efficiency as well as the energy output required to win the Tour de France, I can estimate how much food the winning cyclist needs.
Top Tour de France cyclists who complete all 21 stages burn about 120,000 calories during the race — or an average of about 6,000 calories per stage. On some of the more difficult mountain stages — such as this year’s Stage 12 — racers will burn about 8,000 calories. To compensate for these massive energy losses, riders offer delectable treats like jam rolls, energy bars, and mouthwatering “gels” so they don’t waste energy chewing.
Tadej Pogsar won both the 2021 and 2020 Tour de France and weighed only 146 pounds (66 kg). Tour de France cyclists don’t have much fat to burn for energy. They have to keep adding food energy to their bodies so that they can release the energy at an uncanny rate. So this year, watching a stage of the Tour de France, pay attention to how often cyclists eat out—now you know the reason for all that snacking.
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