Generally they are considered vehicles (like motorcycles and pedal cycles), so are subject to the same rules of the road. Regulations may define maximum power output and for electric bikes may or may not require an interlock to prevent use of power when the rider is not pedaling. In some cases regulatory requirements have been complicated by lobbying in respect of the Segway HT.
In Quebec power-assisted bicycles are often classified similarly to standard pedal bicycles. They do not have to meet the conditions defined within the Canadian Motor Vehicle Safety Regulations (they are not classed as "motor vehicles"), but they do have to comply with federal regulations that define Power Assisted Bicycles. The Quebec Highway Safety Code defines a power-assisted bicycle as a bicycle(2 or 3 wheels that touch the ground) with an electric motor with a maximum power of 500W and a top speed of 32 km/h bearing a specific compliance label permanently attached by the manufacturer[30]. PABs are permitted on the road in the province of Quebec, but riders have to be 14 and over to ride the electric bicycle and if they're under the age of 18, must have a moped or scooter license.
Can I legally buy/build and ride an ebike that’s faster than 20 mph? Yes you can, but you need to know that the ebike is no longer considered equivalent to a bicycle and is subject to other state vehicular classifications. The definitions for electric bikes spanning 20-30mph, and 1-2 horsepower ranges, will vary from state to state, resulting in a no-man’s-land consensus about limits for motor vehicle definition. The common label for a 20-30mph, 2-wheeled vehicle with active pedals is a Moped. Other MVA labels include motor scooter, motorbike and dirt bike which may have equivalent power and speed performance, but do not have pedals to assist and move the vehicle.
An electric bicycle is a bicycle with an electric motor used to power the vehicle, or to assist with pedaling. In many parts of the world, electric bicycles are classified as bicycles rather than motor vehicles, so they are not subject to the same laws as motor vehicles. Electric bicycles are one type of motorized bicycle. However, electric bicycles are defined separately and treated as a specific vehicle type in many areas of legal jurisdiction.
The batteries are the most important parts of the bike, because (if you don't do any pedaling) they contain all the power that will drive you along. Typical electric bike batteries make about 350–500 W of power (that's about 35–50 volts and 10 amps), which is about a quarter as much as you need to drive an electric toaster. In theory, you could use any kind of battery on a bicycle. In practice, however, you want to use something that stores lots of power without being too heavy—or you'll be using half your power just moving the battery along! That tends to rule out heavy lead-acid batteries like the ones that start cars, though some electric bikes do use them. Lightweight lithium-ion batteries, similar to those used in laptop computers, mobile (cellular) phones, and MP3 players, are now the most popular choice, though they're more expensive than older rechargeable battery technologies such as nickel-cadmium ("nicad"). Typical batteries will give your bicycle a range of 10–40 miles between charges (depending on the terrain) and a top speed of 10–20 mph (which is about the maximum most countries allow for these vehicles by law). You can extend the range by pedaling or free-wheeling some of the time.
With hand-operated brakes, force is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads, which apply pressure to the braking surface, causing friction which slows the bicycle down. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were popular in North America until the 1960s.

China's experience, as the leading e-bike world market, has raised concerns about road traffic safety and several cities have considered banning them from bicycle lanes.[2] As the number of e-bikes increased and more powerful motors are used, capable of reaching up to 30 miles per hour (48 km/h), the number of traffic accidents have risen significantly in China. E-bike riders are more likely than a car driver to be killed or injured in a collision, and because e-bikers use conventional bicycle lanes they mix with slower-moving bicycles and pedestrians, increasing the risk of traffic collisions.[2]
Electric bicycles are considered as "bicycles" under Montana law as the law defines bicycles in a two part definition where the first part of the definition describes a conventional bicycle propelled solely by human power and the second part of the definition describes a bicycle equipped with an independent power source for propulsion in addition to foot pedals to permit muscular propulsion. (Montana Code 61-8-102).[104]
Bicycle shall mean (1) every device propelled solely by human power, upon which any person may ride, and having two tandem wheels either of which is more than fourteen inches in diameter or (2) a device with two or three wheels, fully operative pedals for propulsion by human power, and an electric motor with a capacity not exceeding seven hundred fifty watts which produces no more than one brake horsepower and is capable of propelling the bicycle at a maximum design speed of no more than twenty miles per hour on level ground.
With a 150mm-travel RockShox Yari fork and 132mm of rear travel from the RockShox Monarch Plus R shock, the Remote CTRL is Kona’s first dual-suspension e-mountain bike. It’s powered by a 250-watt Bosch Performance Line XC mid-drive motor that uses the company’s progressive E-MTB mode that is adaptable to rider input, which means you don’t have to toggle through assistance modes while riding. It offers assistance up to 20 mph, and the 500Wh integrated battery is the largest Bosch currently offers. Beefy 27.5x2.8-inch Maxxis Recon tires offer plenty of traction and also help to absorb smaller hits.
In the Netherlands all train stations offer free bicycle parking, or a more secure parking place for a small fee, with the larger stations also offering bicycle repair shops. Cycling is so popular that the parking capacity may be exceeded, while in some places such as Delft the capacity is usually exceeded.[64] In Trondheim in Norway, the Trampe bicycle lift has been developed to encourage cyclists by giving assistance on a steep hill. Buses in many cities have bicycle carriers mounted on the front.

Many countries have enacted electric vehicle laws to regulate the use of electric bicycles. Countries such as the United States and Canada have federal regulations governing the safety requirements and standards of manufacture. Other countries like the signatories of the European Union have agreed to wider-ranging legislation covering use and safety of their term EPAC (electric vehicles)
A local unit of government having jurisdiction over a road or bikeway (including the Department of Natural Resources in the case of state bike trails) is authorized to restrict e-bike use if: the use is not consistent with the safety or general welfare of others; or the restriction is necessary to meet the terms of any legal agreements concerning the land on which a bikeway has been established.
Biking is awesome, but biking uphill is not. Commuting by bike is environmentally friendly, fun and good for your health, but presenting your sweaty self to your office coworkers in not fun at all. Fortunately, there is a solution! Electric bicycles offer the same great benefits as traditional bicycles including cost savings, health improving, plus some additional advantages like efficiency in climbing hills, less stress on knees and joints, which is convenient for people of all ages and health.