Originally Posted by
WhyFi
It's wrong in addition to being a gross simplification. As your speed ramps up linearly, resistance ramps up exponentially - the increased time in the saddle, over the same distance, doesn't make up for the increased energy necessary to cover that same distance faster. I see this in practice 3-4x per week on my short ride days. I'll cover the same, boring 18-mile loop, but I'll do it at different intensities, depending upon my cumulative training load at the time. Covering it at 20mph requires a lot more kj than doing so at 16mph.
Exactly.
I can leisurely burn 22 calories per mile at 18 mph on my recumbent or a very difficult 35 calories per mile at 26 mph on my recumbent on the same loop. If I ride my upright bike at those speeds, it would be more like a difficult 34 calories per mile at 18 mph and it is impossible for me now to ride at 26 mph, it would take 360 watts which would be like 55-60 calories per mile in theory off the top of my head.