If you have dynamo-powered bicycle lights, you already own an electric-powered bicycle! Consider: as you pump your legs up and down on the pedals, you make the wheels rotate. A small dynamo (generator) mounted on the rear wheel produces a tiny current of electricity that keeps your back safety lamp lit in the dark. Now suppose you could run this process backward. What if you removed the lamp and replaced it with a large battery. The battery would kick out a steady electric current, driving the dynamo in reverse so that it spun around like an electric motor. As the dynamo/motor turned, it would rotate the tire and make the bike go along without any help from your pedaling. Hey presto: an electric bike! It may sound a bit far-fetched, but this is more or less exactly how electric bikes work.

In principle, you would use about 100W (your own energy) for moderate pedalling at 22km/h. If you select 300% assistance (high), that will add another 300W and you can pedal almost twice as fast, i.e. about 27km/h (you will encounter increasing resistance from wind). Therefore, if you got a 400Wh battery, you got a range of about 37km at 37km/h. If go more slowly and use less support (200%), then you can drive further, e.g. 60km with a 400Wh battery. (Read more in die Die Schnellen im Vergleich)

Most European bike rules are tight and restrictive. Right now the California state ebike rules in AB 1096 provide the clearest and cleanest format, and they support ebike riding. No other U.S. regulations come close. The big brand ebikes (Giant, Specialized, Trek) are selling bikes that fit within European rules (250w-300w motors). This gives them economies of scale.
It is important to note that if a vehicle has an electric motor greater than 500 watts and is capable of powering the vehicle when traveling at a speed greater than 32 km/h and it does not have a CMVSS compliance label it cannot be registered unless the owner can prove, by having the vehicle certified by an engineer, that it is safe for operation on NB highways. Also, not all vehicles are suitable for operation on NB highways and it could be that the vehicle in question may not be a motor driven cycle or a bicycle and cannot be operated on the highway at all.
A lot has happened since we founded the very first eMTB specific magazine in 2013. In the beginning, manufacturers simply mounted electric motors on regular mountain bikes, more or more often than not, rather less successfully. Last year a lot of brands focused on the topic of battery integration. There are some exciting new trends and developments headed our way next season, which we take a closer look at below.
Bicycles and horse buggies were the two mainstays of private transportation just prior to the automobile, and the grading of smooth roads in the late 19th century was stimulated by the widespread advertising, production, and use of these devices.[9] More than 1 billion bicycles have been manufactured worldwide as of the early 21st century.[1][2][3] Bicycles are the most common vehicle of any kind in the world, and the most numerous model of any kind of vehicle, whether human-powered or motor vehicle, is the Chinese Flying Pigeon, with numbers exceeding 500 million.[1] The next most numerous vehicle, the Honda Super Cub motorcycle, has more than 60 million units made, while most produced car, the Toyota Corolla, has reached 35 million and counting.[4][5][6][32]
The safety bicycle gave women unprecedented mobility, contributing to their emancipation in Western nations. As bicycles became safer and cheaper, more women had access to the personal freedom that bicycles embodied, and so the bicycle came to symbolize the New Woman of the late 19th century, especially in Britain and the United States.[8][73] The bicycle craze in the 1890s also led to a movement for so-called rational dress, which helped liberate women from corsets and ankle-length skirts and other restrictive garments, substituting the then-shocking bloomers.[8]
For many ebike owners, doing their ebike thing usually becomes more than a hobby and good exercise on the weekend with the riding club. It becomes a lifestyle, a utility machine, a darn fun piece of technology on two wheels. As the industry grows and becomes more popular, these unique bikes will be a daily part of many lives and mold into the framework of legal society.

As long as the electric bicycle meets three criteria it is considered a low-speed electric bicycle, or simply a "bicycle." Three criteria: must travel less than 20 mph on flat ground without pedaling, must have functional pedals and must have less than a 750 watt motor. This is the same criteria as Federal Public Law 107-319. I checked my facts with the law office of Spohn, Spohn & Zeigler at 144 East Center Street, Marion, OH 43302 on August 21, 2009. A low-speed electric bicycle does not require registration, insurance, license plates (tags), or a driver's license. The rules of an electric bicycle are the same as a traditional bicycle. There is some confusion caused by Ohio interchanging the word Moped with "motorized bicycle." If a dealer sells you a bike that follows the guidelines of Federal Public Law 107-319, then you have a bicycle. If the bike has no pedals or has a higher wattage motor than 750 watts or can travel faster than 20mph you have a moped or scooter; Ohio requires tags and registration for mopeds and scooters.
The recommendation depends a lot on what you plan to use the bike for and how you plan to ride. That said, I would recommend at least a 750 (if not 1,000) watt motor, and, if you want reasonable range, 48 or 52v cells with a minimum rating of 19ah. For shorter rides, you can use a smaller battery. Multiply battery voltage by amp hour rating to get battery watt hours. Divide the watt hours by the motors power rating to get a general idea of how many hours of heavy use you might get. I’d also recommend a mid drive as opposed to a hub drive, or to find a hub drive wheel rated to take your and the bicycle's combined weight.
For people wanting to push the effects of Statorade to the max, the Australian made Hubsinks can clamp on to your motor shell and provide additional cooling fins to shed heat to ambient air. These fit our new MXUS Cassette motors, and the 9C, Crystalyte H, and many others. These are listed on our new store category for motor cooling mods. And like other small products, we try to  keep a stock of 10mL Statorade syringes on Amazon for easy shipping to US customers. They are sold out now but another shipment is inbound. 
In Opinion No. 2007-00602 of the Attorney General, Jim Hood clarified that a "bicycle with a motor attached" does not satisfy the definition of "motor vehicle" under Section 63-3-103. He stated that it is up to the authority creating the bike lane to determine if a bicycle with a motor attached can be ridden in bike lanes. No specifications about the motor were made.
To operate a motorized/electric-assisted bicycle on the streets or highways a person must have a valid driver’s license or a motorized bicycle permit. A person under the age of 16 operating a motorized/electric-assisted bicycle under a motorized bicycle permit is subject to restrictions of no passengers (a parent or guardian my ride if the motorized/electric assisted bicycle is equipped with a seat and footrests for a passenger), no night driving, driving on any highway marked as an interstate, must wear a helmet, foot rests for passengers (if designed for passenger(s). A motorized bicycle permit is available to persons of at least 15 years of age who have passed the motorized bicycle test or passed a motorized bicycle course. A motorized bicycle would need the same coverage as a motorcycle would in this state. An electric-assisted bicycle would not need coverage.