http://www.marketwatch.com/story/pe...wer-solution-for-electric-bicycles-2010-09-23
For every 1.5 lbs. of weight a rider carries, an additional 700 watt-hours of energy is available (compared to ~350 watt-hours for an ultra-high performance lithium-polymer battery at a weight of 7 lbs.). The Pedego -- SiGNa hybrid system utilizes the battery for peak conditions such as acceleration and hill climbing, while the fuel cell to extend the operating range of a Pedego bicycle by over 40 miles for each additional cartridge