Departure of the Puy-en-Velay for the Rhône Valley: We have a very covered weather, our batteries are at the lowest! 1250 m of positive elevation is waiting for us, so our legs will be our main engine. Negative 1766m: Bicycles that have a "regeneration" function will be able to recharge their batteries. These are the ones whose unducted motor is located in the hub of a wheel. Their engine turns into a generator, much like a dynamo. A chance, that's the case of my bike!