Originally Posted by
OBoile
https://www.youtube.com/watch?v=leLgmwcz0dU
Same speed, same weight. Different power requirements. Hmmm maybe an arbitrary scale that was done for 821 activities isn't all that accurate for any given one?
https://www.slowtwitch.com/Tech/The_..._Bike_163.html
You'll note that a rider's mass is really only a factor in calculation of the tire drag and that is a fairly small portion of the overall effort, particularly at high speeds.
The force required to overcome wind resistance is proportional to the square of the speed (mass again not a factor).
https://en.wikipedia.org/wiki/Drag_(physics)
Does your precious METS calculation consider whether a person is drafting or not, what position they are in on the bike, whether there is a headwind or not? These all affect the amount of power you put out.
But seriously, you're trolling here right? If so, well played. If not... yikes.
The basic assumption is that the resting calorie needs of a heavy person are greater than that of a thinner person, and activities are calculated by using a multiple of the resting calorie burn with the multiple being defined by the intensity of the activity. So, no matter what the activity is, the heavier person is going to be credited with burning more calories for the same amount of exercise. Basically, it's all guesstimate, with assumption being multiplied by assumption, and is useless for estimating what you actually burned for a given activity.