Electric bicycle

Electric bicycles, also called e-bikes or power-assisted bicycles, are pedal cycles with a battery-powered electric motor to assist riders when pedaling or, in some cases, through a throttle. While an attached electric motor provides assistance, to classify as an electric bicycle, it must assist the rider rather than propel the bike on its own.

Pushing the pedals on an electric bicycle engages an electric motor giving the rider a boost, which is particularly helpful when riding up hills or over rough terrain. When the rider peddles harder, the electric bicycle provides a greater boost, up to a point. There is different regulation around the world regarding how much power the motor can provide and the speed at which the assistance cuts out. Most models allow users to control how much of an assist the electric motor provides with multiple boost settings, in order to balance the power supplied through the pedals with range and battery life. Power for the motor is provided through a rechargeable battery mounted on the bike.

Electric bicycles typically house the motor centrally on the bike (often referred to as a mid-drive motor) or on either the front or rear hub, pushing the wheels directly.

Example of an electric motor mounted on a wheel hub.

As the rider pedals, a torque sensor measures their output and provides a set level of power (depending on many factors such as model, boost setting, battery life, etc.). Generally, the motor should provide consistent power delivery without ending the bike lurching forward. A battery powering the motor is mounted on the outside of the frame or hidden within it. The battery is either removed for charging or must be charged while on the bike.

With the addition of the motor, battery, and other components (e.g., additional mounts and frame reinforcements), electric bicycles are heavier than traditional bikes. This weight increase varies significantly depending on the design of a specific motor/battery system. The lightest electric bicycles are road bikes with less than 8.8 pounds (4kg) added. However, most systems weigh roughly 13.2-17.6 pounds (6-8kg) or more.

Electric bicycle batteries can provide anywhere between 20 to 100 miles range on a full charge, depending on their capacity (measured in watt-hours). Most models provide a battery level indicator, while other control systems give an estimated range during the ride. Some allow riders to switch batteries to increase the range. The price of an electric bicycle generally governs its weight and battery range.

The first electric bicycles were developed in the late nineteenth century, with the first patents issued by the US patent office between 1895 and 1899:

• Ogden Bolten patented a battery-powered bicycle
• Hosea W. Libbey patented a bicycle with a double electric motor
• John Schnepf patented an electric motor with a roller wheel

However, it took until the 1990s for the weight and range of electric motor/battery systems to develop enough to be suitable for electric bicycles. In the late 1990s, the first models with torque sensors and power controls became available. One of the electric bicycles to find commercial success was the "Select" model released in 1997. By the next year, there were more than forty-nine different electric bicycle models available on the market.