Originally Posted by Ric Stern

Previous research (Coyle et al 1991) used force instrumented pedals and they showed that better cyclists (national/international) stomped down more and pulled up less compared to less good cyclists (regional/county/state -- i'm not sure of the exact terminology).
your endurance (whether that's an event that is >90-secs - yes seconds, or one that is some sort of ultra endurance event lasting multiple hours to days) is affected by a variety of factors, which include in no particular order:
*FTP
*VO2max
*psychological factors
*nutrition
*training status
*etc

If you take an event such as The Transcontinental Race (an extreme ultra event taking the winner around 10 days or so) a large ability to do well is simply related to their FTP. This is also apparent for really short endurance events (e.g. anything from about 90-secs onwards). For most athletes once an exercise lasts for 90-secs or more it's primarily fuelled by your aerobic system such that by the time you're exercising maximally for 4-mins about 80% of the energy is derived aerobically.

So, on average, if you took two cyclists who weighed the same, and one athlete had an FTP that was say 4 W/kg and the other had 6 W/kg then the 6 W/kg athlete will be significantly better from 90-secs thru to multiple days. (This is on average, you WILL find examples that disagree with that). On the other hand two cyclists of the same mass with 4.0 and 4.1 W/kg it's anyone's guess who would be better at a variety. of different durations. Fatigue (and thus endurance) is multifactorial.

Note, that i've ignored differences in CdA for these illustrative purposes.