Just thought I should add a bit to my post.
Let's say, for argument's sake, the maximum power-weight ratio of a pro cyclist is 6.3W. This seems to be an almost universal number. I find this quite hard to believe between all the different body types and sizes out there. With torque being mostly a muscular issue, I can see how training at a higher torque range for longer periods of time could allow one to have higher power outputs than normal. I think my theory applies more to the upper limits of performance, ie. when all the normal avenues of training have been maxed out.
I know cycling is mostly cardiovascular but, any cyclist knows muscular strength does come into play.
I wonder if you perhaps have some interesting ideas or are perhaps not communicating what you really mean?
6.2 W/kg is the max quoted power::weight figure for FTP - "the power sustainable for 1 hour" - not the "maximum power-weight ratio of a pro cyclist". I and many on this board exceed that value when sprinting, Brad McGee et al when pursuiting and the top 10-20 pro cyclists in most prologue stages (<10 minute effort).
I also think you'll find that 6.2W/kg for FTP is not universal - but applies to the top .1% (or less, it's a guesstimate) of pro cyclists. Just count the number of riders finishing first at the top of the big cols in one of the 3 GTs.
If by "muscular strength" you mean "ability to squat a heavy weight" - ie between 1 and 10 reps, then I completely disagree. I can ride rings around other cyclists who can squat significantly more than I can squat. At any distance. My sample includes a quicker flying 200m vs a sprinter who trains specifically for the event, who can squat 205kg vs me not doing squats or any weights at all. The most I have ever squatted is 70kg, but that was years ago. You could almost say muscular strength means diddly squat
Power is work done. Torque, when discussing power, is irrelevant without taking into account the cadence at which the torque is generated, and you are immediately back to your aerobic capacity for any event longer than 12 seconds, because your muscles cannot do ongoing work without oxygen.
In the context of generating power on the bike, muscular strength is mostly irrelevant.
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