Modern Living: The Effortless Bike

It looks like an overbuilt bicycle, sounds like an impatient teakettle and, in fact, combines pedal power with petroleum push. Called a moped (from motor-plus-pedals), the motorized bike is catching on rapidly in the U.S. as a practical, inexpensive form of short-haul transportation for commuters, students, the elderly and fresh-air lovers out for a spin—not to mention the suburban housewife who is reluctant to drive a gas-guzzling, nine-passenger station wagon two miles for a can of tuna. Since it whirs along on a two-stroke minimotor with less horsepower than a power mower, goes no faster than 30 m.p.h. and can be...