Lance cutting the switchback was likely not in 'unbearable pain', because it was towards the bottom of the descent. The only guy in unbearable pain in that situation was Joseba Beloki - because he crashed and broke his leg and some other bones. They rode down that same road this year, by the way... it was kind of cool - someone had cut a path through the grass.
> An elite runner or cyclist or whatever can tell the difference between pain that will go away when you slow down, and pain that will get worse or could put you into a wheelchair.
I don't think you need to be all that 'elite' to figure that out. You don't need too much training to start feeling what sort of pain is from effort and exertion, and what might be tendons or joints or something like that that should not be pushed beyond a certain point.
> An elite runner or cyclist or whatever can tell the difference between pain that will go away when you slow down, and pain that will get worse or could put you into a wheelchair.
I don't think you need to be all that 'elite' to figure that out. You don't need too much training to start feeling what sort of pain is from effort and exertion, and what might be tendons or joints or something like that that should not be pushed beyond a certain point.