Powered by lightweight batteries, Ivan Stewart's electric bicycles propel riders around downtown San Diego at speeds of up to 20 miles per hour. Hills and rough terrain won't slow down tours as the electric bikes tackle road obstacles with ease. The self-powered cycles can travel between 20 and 25 miles on a single charge, letting renters explore large parts of the city and its waterfront before needing to plug into a power source or capture stray lightning bolts.