Joined: Jul 2006
Posts: 9,158
Likes: 1,743
From: Lebanon (Liberty Hill), CT
Bikes: Canyon Aeroad, CAAD 12, MASI Gran Criterium S, Colnago World Cup CX, Guru steel & Guru Photon
As it was explained to me the "energy" you use up spinning can be replenished by food/drink while riding but the energy you use when powering can only be replenished by rest. Once the latter is depleted you are done. More technical than that but I've tried to simplify my understanding of it.