Historically, women's bicycle frames had a top tube that connected in the middle of the seat tube instead of the top, resulting in a lower standover height at the expense of compromised structural integrity, since this places a strong bending load in the seat tube, and bicycle frame members are typically weak in bending. This design, referred to as a step-through frame or as an open frame, allows the rider to mount and dismount in a dignified way while wearing a skirt or dress. While some women's bicycles continue to use this frame style, there is also a variation, the mixte, which splits the top tube laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends. The ease of stepping through is also appreciated by those with limited flexibility or other joint problems. Because of its persistent image as a "women's" bicycle, step-through frames are not common for larger frames.
Electric bikes are a green alternative to driving a vehicle. Studies carried out in several towns and cities show that the average car speed in rush hour traffic can dip as low as 18 to 20 mph. Electric bike speed can be as high as 15 mph. With an electric bike, you can reduce pollution, improve fitness, and still arrive at the same time as your car-bound colleagues.
The federal Consumer Product Safety Act defines a "low speed electric bicycle" as a two or three wheeled vehicle with fully operable pedals, a top speed when powered solely by the motor under 20 mph (32 km/h) and an electric motor that produces less than 750 W (1.01 hp). The Act authorizes the Consumer Product Safety Commission to protect people who ride low-speed electric vehicles by issuing necessary safety regulations.[63] The rules for e-bikes on public roads, sidewalks, and pathways are under state jurisdiction, and vary.
Because e-bikes are capable of greater speeds for longer periods of time than standard bikes, you want extra control. Wider tires provide traction and some bump absorption with little penalty. You also want strong brakes to slow you (and all that extra weight) easily. It’s worth looking at the quality of the brakes and investing in bikes with better ones if you can.

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 Consumer Product Safety Commission(CPSC) stipulates that commercially manufactured low-speed electric bicycles, or tricycles, must have fully operable pedals, an electric motor not exceeding 750W of power and a top motor-powered speed not in excess of 20 miles per hour (32 km/h).[22] An electric bike remaining within these specifications will be regarded simply as a bicycle for purposes of safety standards. This supersedes any state law that is more stringent, but only regarding safety equipment required on electric bicycles and the standard of manufacture they must meet.[23]. The legislation enacting this amendment to the CPSC is also known as HR 727[24].

The bicycle's invention has had an enormous effect on society, both in terms of culture and of advancing modern industrial methods. Several components that eventually played a key role in the development of the automobile were initially invented for use in the bicycle, including ball bearings, pneumatic tires, chain-driven sprockets and tension-spoked wheels.[10]

Riding position: You also may wish to check out an e-bike’s riding position before investing in it. For short trips, the riding position might not make much difference, but for long journeys, the upright "Dutch" style with pulled-back handlebars is very comfortable – particularly for tall riders. The same goes for mountain bike styles, though these bikes are not often designed to actually go off-road.
None of this would matter if the VanMoof Electrified S2 (and its close relative the X2) wasn't fun to ride, but it is a blast. Like the Brompton, it pulls off the neat trick of powering you along but giving the illusion that you're doing the work, reacting quickly and cleverly to the speed of your pedalling and the difficulty of any incline you're on. 
In New Zealand, the regulations read: "AB (Power-assisted pedal cycle) A pedal cycle to which is attached one or more auxiliary propulsion motors having a combined maximum power output not exceeding 300 watts."[56] This is explained by NZTA as "A power-assisted cycle is a cycle that has a motor of up to 300 watts. The law treats these as ordinary cycles rather than motorcycles. This means that it is not necessary to register or license them.[57] Note that the phrase "maximum power output" that is found in the regulation (but omitted in the explanation) may create confusion because some e-bike motor manufacturers advertise and print on the motor their "maximum input power" because that number is larger (typically motors run at about 80% efficiency [58]) thus give the impression the buyer is getting a more powerful motor. This can cause misunderstandings with law enforcement officers who do not necessarily understand the difference, and when stopping a rider on an e-bike in a traffic stop, look at the number on the motor to determine if the e-bike is legal or not.
It appears Tennessee has not passed any legislation that applies to electric bicycles. Some people think the laws pertaining to a Motorized Bicycle should be used for an electric bicycle. However, a Motorized bicycle would be a gasoline powered device per state law as it is defined as "means a vehicle with two (2) or three (3) wheels, an automatic transmission, and a motor with a cylinder capacity not exceeding fifty cubic centimeters (50cc) which produces no more than two (2) brake horsepower and is capable of propelling the vehicle at a maximum design speed of no more than thirty miles per hour (30 mph) on level ground." [56]
Massachusetts General Laws define three classes of motorized two-wheeled vehicles: Motorcycle, Motorized bicycle, and Motorized scooter.[98] Although the definition of motorized scooter includes two-wheeled vehicles propelled by electric motors with or without human power, motorized scooter specifically excludes anything which falls under the definitions of motorized bicycle and motorcycle. 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. Motorcycle includes any bicycle with a motor or driving wheel attached, with the exception of vehicles that fall under the specific definition of motorized bicycle. Thus, a pedal bicycle with an electric motor or a non-pedal bicycle with an electric motor, automatic transmission, and maximum speed of 30 miles an hour would fall under the definition of motorized bicycle. An electric bicycle that did not meet those restrictions would be either a motorized scooter or motorcycle, depending on specific characteristics.
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. 

Haibike ships the HardNine with 29-inch tires, 180-millimeter hydraulic disc brakes, a 100-millimeter front suspension fork, and a nine-speed Shimano shifting system. The bike’s LCD readout is affixed to the handlebars and displays the current speed, level of charge, remaining range, and current pedal assist mode. The company says the battery can be completely recharged in just four hours, minimizing downtime between rides.
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