Bicycles were introduced in the late 19th century in Europe, and by the early 21st century, more than 1 billion were in existence at a given time. These numbers far exceed the number of cars, both in total and ranked by the number of individual models produced. They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for use as children's toys, general fitness, military and police applications, courier services, bicycle racing and bicycle stunts.
(2) BICYCLE.--Every vehicle propelled solely by human power, and every motorized bicycle propelled by a combination of human power and an electric helper motor capable of propelling the vehicle at a speed of not more than 20 miles per hour on level ground upon which any person may ride, having two tandem wheels, and including any device generally recognized as a bicycle though equipped with two front or two rear wheels. The term does not include such a vehicle with a seat height of no more than 25 inches from the ground when the seat is adjusted to its highest position or a scooter or similar device. No person under the age of 16 may operate or ride upon a motorized bicycle.
There are individuals who claim to have lost considerable amounts of weight by using an electric bike. A recent prospective cohort study however found that people using e-bikes have a higher BMI. By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able. This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer.