A lot of people trust the absolute calorie burn estimates provided by bicycles (stationary or moving) that have a power meter of some sort. But, the total calorie burn of the rider depends on knowing the rider's efficiency, which is, on average, about 20%. This means that you (or your bike computer) must take the energy expended on actual pedaling and multiply it by 5 to get the number of calories consumed by your body.
Many people think this efficiency is pretty much the same for everyone. One reason they think that is the title of the paper "No Differences in Cycling Efficiency Between World-Class and Recreational Cyclists," Mosley, et. al, Int. J. Sports Med (2004). (And other works based on it.)
I've posted this before, but the problem with this paper's title is that it really means that the average efficiency
of each cohort
("world-class" or "recreational") is about the same. But the paper also shows that there is wide variation between individuals making up the entire study.
For illustration, here's a figure from the paper that shows that both the "GE165" (the efficiency factor) and the VO2max vary quite widely from person-to-person (each individual being a single data point). The point of the figure is to show that the two metrics are pretty much uncorrelated, but it also shows that the GE165 varies from 14 to 22% for people tested.
Note that the "GE165" is defined in the paper as
((Work Rate [W]/Energy Expended [J/s]) * 100%, as measured for an individual at a power output of 165W[/quote]
Here's a link to the paperhttps://www.usada.org/wp-content/uploads/R060.pdf
Comments welcome. (Particularly if I'm misinterpreting something! I am not an expert in this field.)