The two most common types of hub motors used in electric bicycles are brushed and brushless. Many configurations are available, varying in cost and complexity; direct-drive and geared motor units are both used. An electric power-assist system may be added to almost any pedal cycle using chain drive, belt drive, hub motors or friction drive. BLDC hub motors are a common modern design. The motor is built into the wheel hub itself, and the stator fixed solidly to the axle, and the magnets attached to and rotating with the wheel. The bicycle wheel hub is the motor. The power levels of motors used are influenced by available legal categories and are often, but not always limited to under 750 watts.
China has experienced an explosive growth of sales of non-assisted e-bikes including scooter type, with annual sales jumping from 56,000 units in 1998 to over 21 million in 2008,[72] and reaching an estimated fleet of 120 million e-bikes in early 2010.[2][73] This boom was triggered by Chinese local governments' efforts to restrict motorcycles in city centers to avoid traffic disruption and accidents. By late 2009 motorcycles are banned or restricted in over ninety major Chinese cities.[72] Users began replacing traditional bicycles and motorcycles and e-bike became an alternative to commuting by car.[2] Nevertheless, road safety concerns continue as around 2,500 e-bike related deaths were registered in 2007.[73] By late 2009 ten cities had also banned or imposed restrictions on e-bikes on the same grounds as motorcycles. Among these cities were Guangzhou, Shenzhen, Changsha, Foshan, Changzhou, and Dongguang.[72][73]
But if you're someone who loves riding, commutes to work on a bike, or has a gig that requires you to spend a lot of time in the saddle, you might want to look at electric bikes. You'll be able to go farther, faster, and expend less energy riding one. And if electric bikes are for you, look hard at the Cross E8 Step-Thru. It's an incredibly well-made, well-thought-out electric bike. Strip away the battery, motor, and computer, and you'd still be left with a really good cycle.
An electric bicycle also known as an e-bike is a bicycle with an integrated electric motor which can be used for propulsion. Many kinds of e-bikes are available worldwide, from e-bikes that only have a small motor to assist the rider's pedal-power (i.e., (pedelecs) to somewhat more powerful e-bikes which tend closer to moped-style functionality: all, however, retain the ability to be pedalled by the rider and are therefore not electric motorcycles.
Firstly there's a magnetically-fired locking pin in the rear wheel, triggered by kicking a button on the hub. This is fairly secure in itself and almost impossible to remove without destroying the bike. In London, we'd pair it with a more traditional bike lock so there's a more obvious visual deterrent, though a LED matrix screen on the frame does issue a warning to would-be tea-leafs.
If you are a regular bicyclist who wants to add some excitement to your rides or wants some help with those hills, a full sized electric bike is the way to go. If you are considering a bike as a means of transportation more than an outlet for amusement, then a smaller, folding electric bike is the convenient choice. In each category, consider the speed and range you want, as these factors impact price.
A response to an inquiry made to the Mass DOT/RMV indicates that Massachusetts does recognize the federal low speed electric bicycle Federal Law (15 U.S.C. § 2085) and interprets that to mean these ebikes do not require license or registration. However, some of the materials available on the RMV website do not distinguish between "Motorized Bicycle" and low power ebikes. One form, Bicycle Conversion to Motorized Bike, does document the exemption of low power ebikes.[100]
E-bike usage worldwide has experienced rapid growth since 1998. In 2016 there were 210 million electric bikes worldwide used daily.[33] It is estimated that there were roughly 120 million e-bikes in China in early 2010, and sales are expanding rapidly in India, the United States of America, Germany, the Netherlands,[2] and Switzerland.[34] A total of 700,000 e-bikes were sold in Europe in 2010, up from 200,000 in 2007 and 500,000 units in 2009.[35]

The legal definition/description of an electric bicycle is most closely described in the code as a "motorized scooter" in that it is powered by an electric motor and/or human power [45]. It may be also be described as a "Motorized bicycle". However, that description does not include electric powered motor specifically. And it appears that the legal definition "Motorized Bicycle" and "Motorized Scooter" are in conflict. Motorized bicycle is a pedal bicycle which has a helper motor, or a non-pedal bicycle which has a motor, with a cylinder capacity not exceeding fifty cubic centimeters, an automatic transmission, and which is capable of a maximum speed of no more than thirty miles per hour. A motorized bicycle shall not be operated upon any way, as defined in section one within the commonwealth by any person under sixteen years of age, nor at a speed in excess of twenty-five miles per hour. A motorized bicycle shall not be operated on any way by any person not possessing a valid driver’s license or learner’s permit. Every person operating a motorized bicycle upon a way shall have the right to use all public ways in the commonwealth except limited access or express state highways where signs specifically prohibiting bicycles have been posted, and shall be subject to the traffic laws and regulations of the commonwealth and the regulations contained in this section, except that the motorized bicycle operator may keep to the right when passing a motor vehicle which is moving in the travel lane of the way, and the motorized bicycle operator shall signal by either hand his intention to stop or turn. Motorized bicycles may be operated on bicycle lanes adjacent to the various ways, but shall be excluded from off-street recreational bicycle paths. Every person operating a motorized bicycle or riding as a passenger on a motorized bicycle shall wear protective headgear conforming with such minimum standards of construction and performance as the registrar may prescribe, and no person operating a motorized bicycle shall permit any other person to ride a passenger on such motorized bicycle unless such passenger is wearing such protective headgear.
The drivetrain begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A very small number of bicycles use a shaft drive to transmit power, or special belts. Hydraulic bicycle transmissions have been built, but they are currently inefficient and complex. 
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