You probably do have to wonder whether such a high cadence actually makes sense physically.
This is the mystery (at least for me). And it’s his party piece, along with the ability to sustain the higher speed (thereby indicating that he doesn’t go into oxygen debt, that he has no red zone that means he has to pay for the effort soon after). He’s on a steep climb, at the end of the race. Vingegaard is setting a pretty high pace already. The context is interesting and relevant I think. Energy state, fatigue etc. And despite that context Pogacar, just appears to ‘flick a switch’ and accelerates away. Sprints in fact. It doesn’t pass the eye test, at least for myself. It literally looks like a guy not so much with just a bigger oxygen tank (as say EPO would provide) gradually putting distance into an opponent , than a guy on an e-bike who has hit the power button. Because otherwise where is the additional power coming from? Switching to a bigger gear and upping the cadence would be the only way that he gaps Vingegaard over that relatively short distance. But is that possible on such a slope at the end of a brutal stage? How does he generate the additional power without at least getting off the saddle? And even then where does he get the instant energy to accelerate away like that? In this case I note Jonas giving a rueful shake of his head just before he crosses the line. Disappointment perhaps, but also I think a certain level of incredulity.