>>1784583Ideally there would be some sort of regenerative braking system, that you would charge going downhill, and use for uphill. I would avoid electric system, because you get in electric assisted bike territory and (future) regulations and I don't think they would care to distinguish electric assisted bike vs. electric brake recovery bike.
One way would be pneumatic. Although there is nothing on the market as whole system. You would have to use 300bar scuba tanks and pump and I don't know what efficiency you would get out of the system against the additional weight.
6 liter at 300bar could move straight up 120kg object between 300- 900 meters, depending on expansion type, according to my quick calculations. Not factoring in any inefficiencies.
