An electric bicycle (eBike) is a motorized bicycle with an integrated electric motor used to assist propulsion. Many kinds of e-bikes are available worldwide, but they generally fall into two broad categories: bikes that assist the rider’s pedal power (i.e. pedelecs) and bikes that add a throttle, integrating moped-style functionality.
Ebike use is growing in some markets, as they are seen as an eco-friendly and healthy alternative to cars, fossil fuel-powered mopeds, and small motorcycles, and a less intense physically intense alternative to conventional bicycles.
Depending on local laws, many e-bikes (e.g., pedelecs) are legally classified as bicycles rather than mopeds or motorcycles. This exempts them from the more stringent laws regarding the certification and operation of more powerful two-wheelers which are often classed as electric motorcycles. E-bikes can also be defined separately and treated under distinct electric bicycle laws. In UK legislation the vehicles are called EAPC or Electrically Assisted Pedal Cycle, in EU legislation EPAC or Electrically Power Assisted Cycle.
In the 1890s, electric bicycles were documented within various U.S. patents. For example, on 31 December 1895, Ogden Bolton Jr. was granted U.S. Patent 552,271 for a battery-powered bicycle with a “6-pole brush-and-commutator direct current (DC) hub motor mounted in the rear wheel”. There were no gears and the motor could draw up to 100 amperes (A) from a 10-volt battery.
Two years later, in 1897, Hosea W. Libbey of Boston invented an electric bicycle (U.S. Patent 596,272) that was propelled by a “double electric motor”. The motor was designed within the hub of the crankset axle. This model was later re-invented and imitated in the late 1990s by Giant Lafree e-bikes.
E-bikes are classed according to the power that their electric motor can deliver and the control system, i.e., when and how the power from the motor is applied. Also, the classification of e-bikes is complicated as much of the definition is due to legal reasons of what constitutes a bicycle and what constitutes a moped or motorcycle. As such, the classification of these e-bikes varies greatly across countries and local jurisdictions.
Despite these legal complications, the classification of e-bikes is mainly decided by whether the e-bike’s motor assists the rider using a pedal-assist system or by a power-on-demand one. Definitions of these are as follows:
- With pedal assist, the electric motor is regulated by pedalling. The pedal assist augments the efforts of the rider when they are pedalling. These e-bikes – called pedelecs – have a sensor to detect the pedalling speed, the pedalling force, or both. Brake activation is sensed to disable the motor as well.
- With power-on-demand, the motor is activated by a throttle, usually handlebar-mounted just like on most motorcycles or scooters.
Therefore, very broadly, e-bikes can be classed as:
- E-bikes with pedal assist only: either pedelecs (legally classed as bicycles) or S-Pedelecs(often legally classed as mopeds)
- Pedelecs: have pedal-assist only, motor assists only up to a decent but not excessive speed (usually 25 km/h or 16 mph), motor power up to 250 W (0.34 hp), often legally classed as bicycles
- S-Pedelecs: have pedal-assist only, motor power can be greater than 250 W (0.34 hp), can attain a higher speed (e.g., 45 km/h or 28 mph)) before the motor stops assisting, sometimes legally classed as a moped or motorcycle.
- E-bikes with power-on-demand and pedal-assist
- E-bikes with power-on-demand only: often have more powerful motors than pedelecs but not always, the more powerful of these are legally classed as mopeds or motorcycles
E-bike use was shown to increase the amount of physical activity. E-bike users in seven European cities had 10% higher weekly energy expenditure than other cyclists because they cycled longer trips.
E-bikes can also provide a source of exercise for individuals who have trouble exercising for an extended time (due to injury or excessive weight, for example) as the bike can allow the rider to take short breaks from pedaling and also provide confidence to the rider that they’ll be able to complete the selected path without becoming too fatigued or without having forced their knee joints too hard (people who need to use their knee joints without wearing them out unnecessarily may in some electric bikes adjust the level of motor assistance according to the terrain). A University of Tennessee study provides evidence that energy expenditure (EE) and oxygen consumption (VO2) for e-bikes are 24% lower than that for conventional bicycles, and 64% lower than for walking. Further, the study notes that the difference between e-bikes and bicycles is most pronounced in the uphill segments.