To qualify as an electric-assisted bicycle under state law they need to have a seat and fully operable pedals for human propulsion, meet federal motor vehicle safety standards, an electric motor that has a power output of not more than 1,000 watts, maximum speed of not more than 20 mph (electric motor and human power combined), disengages or ceases to function when the vehicle’s brakes are applied, two or three wheels 

Federal law in the United States states that an electric bicycle must have a top speed under 20 mph and a motor which produces less than 750 watts/1 hp. They are not considered motor vehicles by the federal government and are subject to the same consumer safety laws as unassisted bicycles.[11] Their legality on public roads is under state jurisdiction, and varies. See the main Electric bicycle laws article for details on the law in individual states.
Bicycles helped create, or enhance, new kinds of businesses, such as bicycle messengers,[92] traveling seamstresses,[93] riding academies,[94] and racing rinks.[95][94] Their board tracks were later adapted to early motorcycle and automobile racing. There were a variety of new inventions, such as spoke tighteners,[96] and specialized lights,[91][96] socks and shoes,[97] and even cameras, such as the Eastman Company's Poco.[98] Probably the best known and most widely used of these inventions, adopted well beyond cycling, is Charles Bennett's Bike Web, which came to be called the jock strap.[99]

Tires vary enormously depending on their intended purpose. Road bicycles use tires 18 to 25 millimeters wide, most often completely smooth, or slick, and inflated to high pressure in order to roll fast on smooth surfaces. Off-road tires are usually between 38 and 64 mm (1.5 and 2.5 in) wide, and have treads for gripping in muddy conditions or metal studs for ice.

Vehicles exceeding any of the criteria above must be registered and titled as a motorcycle. Other types of vehicles, such as electric scooters, "pocket rockets" and mini-choppers, may fit the definition of a moped or a motorcycle, but cannot be registered by the Department of State if they lack the equipment required by law to legally drive on public roads.[101]

Electric-assisted bicycle operators must follow the same traffic laws as operators of motor vehicles (except those that by their nature would not be relevant). The bicycles may be operated two abreast. Operators must generally ride as close as is practical to the right-hand side of the road (exceptions include when overtaking another vehicle, preparing for a left turn, and to avoid unsafe conditions). The bicycle must be ridden within a single lane. Travel on the shoulder of a road must be in the same direction as the direction of adjacent traffic.
Under New Jersey law a motorized bicycle is "a pedal bicycle having a helper motor characterized in that either the maximum piston displacement is less than 50 cc, the motor is rated at no more than 1.5 brake horsepower, or it is powered by an electric drive motor and the bicycle is capable of a maximum speed of no more than 25 miles per hour on a flat surface."[107] This would include E-bikes, meaning they must be titled and registered. However, only Mopeds approved by Motor Vehicle Services can be titled and registered.
The pedals on a motorised bicycle must be the primary source of power for the vehicle. If the motor is the primary source of power then the device cannot be classed as a motorised bicycle. For example, a device where the rider can twist a throttle and complete a journey using motor power only without using the pedals, would not be classed as a motorised bicycle.
We rode the Vado through the gauntlet, including some of the steepest hills in Palo Alto, and it easily handled everything we threw at it, maintaining a steady 20 miles per hour even on the most daunting of ascents. The bike also handles well on downhills and is both nimble and quick on city streets and paved trails. It’s even comfortable to ride for extended distances, which is vitally important for any bike built for urban settings.
At 42 pounds for a size medium frame (exceptionally light for an urban e-bike), this step-through model’s silent, mid-drive Bosch Active Line motor provides pedal assist up to 20 mph. And its 400Wh battery lasts a claimed 30 to a whopping 110 miles, depending on mode, speed, terrain, rider weight, cargo—all the usual stuff. With 26-inch wheels, 2-inch tires, round aluminum tubes, a swept-back handlebar, Shimano Sora 9-speed components, and an 11-32 cassette, the Parkway looks like an everyday, non-motorized city bike at first glance. But with an array of Bosch e-components—motor, battery, and Purion display—it has the zip to take you farther faster.
As of May 19, 2009, Nevada amended its state transportation laws to explicitly permit electric bicycles to use any "trail or pedestrian walkway" intended for use with bicycles and constructed with federal funding, and otherwise generally permits electric bicycles to be operated in cases where a regular bicycle could be. An electric bicycle is defined as a two- or three-wheeled vehicle with fully operable pedals with an electric motor producing up to 1 gross brake horsepower and up to 750 watts final output, and with a maximum speed of up to 20 miles per hour on flat ground with a 170 pound rider when powered only by that engine. (AB441, amending NRS 480, 482 and other sections)
The Freedom’s motor gives you five different levels of boost, and the 36-volt battery offers up to 35 miles of range. You can track your power level and speed, as well as your battery life, on a digital display mounted to the handlebar. I have to admit I spent nearly all my time on the Freedom riding in the highest level, where I could pedal up to 19 mph to 20 mph without even breaking a sweat.
The Bulls Cross E8 Step-Thru is an urban bike—a bicycle often used as a primary mode of transportation for those who choose not to own a car. Priced at $3,099, it's solid and durable. The aluminum frame comes in three sizes (45cm, 50cm, and 53cm; I tested the latter). It's got an eight-speed Shimano shifter and a Shimano Deore CS-HG50 cassette. Shimano is a small change for me, as my XO2 uses the SRAM Rival Double Tap shifter, and I really like the action on that. It's got a front suspension with 63mm of travel for a smoother ride, along with Shimano hydraulic disc brakes. Cable runs are all internal, making for a cleaner-looking profile. Rack, fenders, and a headlight all come standard.
E-bikes are typically offered in 24V, 36V and 48V configurations. Higher voltage generally means higher top speed – but that may not always be the case. Since the efficiency of a motor and drive system can have an effect on power and speed, a 24V setup could have the same top speed as a 36V setup. Generally you can expect 15-18 mph on a 24v setup, 16-20 mph on a 36V setup and 24-28 mph on a 48V setup. Although it far exceeds Federal laws, some conversion kits can even be run at 72V for speeds of 35+ mph! However, this puts significant stress on bicycle components. Consider that even the fastest athletes only travel 17-18 mph on a conventional bicycle, so 20 mph feels very fast to most riders. Anything over this speed can be unsafe and exceeds law regulations.
In Australia the e-bike is defined by the Australian Vehicle Standards as a bicycle that has an auxiliary motor with a maximum power output not exceeding 200 W without consideration for speed limits or pedal sensors.[1] Each state is responsible for deciding how to treat such a vehicle and currently all states agree that such a vehicle does not require licensing or registration. Various groups are lobbying for an increase in this low limit to encourage more widespread use of e-bikes to assist in mobility, health benefits and to reduce congestion, pollution and road danger. Some states have their own rules such as no riding under electric power on bike paths and through built up areas so riders should view the state laws regarding their use. There is no licence and no registration required for e-bike usage.
The Ancheer comes with outstanding Shimano Tourney gears in 6 x speeds. This gear system is one of the best in the business. Similarly the front-rear disc brakes are perfectly effective and will bring you to a safe stop even from speed. Speaking of speed, the maximum is 16mph and the bike will travel anywhere between 17-23 miles on a single charge. The battery charges up in 4-6 hours, which is the same for virtually all e-bikes.
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 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.
I do not recommend hacking a bike into s-pedelec, i.e. make a 25km/h bike go at 45 or faster. If you have an accident you will be in trouble. Just get a legal version. In addition you will have good insurance. Of course, in countries like France or the UK that so far do not know S-Pedelecs, you will have to make a difficult moral choice.... At least, make sure that your rig is safe...
At just 36V and 5.2 Ah, the battery is not designed for long distance travel. GOTRAX claims the Shift S1 has a range of up to 15 miles (25 km), though that’s only with a lower pedal assist level. If you’re going full throttle, 10 miles (15 km) is a better estimate. But with a battery this small, you could easily charge it at your desk or in the corner of the classroom – lengthening your effective range.
My homeowners (State Farm) covers bikes , but assumes $500 per bike. They will add the bikes as personal property, but the premium is excessive (about $300/year per bike, and we have four bikes). I did increase our personal umbrella liability coverage, and it covers us if family members any sort of accident on our e-bikes that injures us or others or others' property, though only covers $500 each for our own bikes (under the homeowners coverage). It was not very expensive to increase the umbrella policy (as it resulted also in a reduced rate on our car insurance).
If you are a person who enjoys riding a bike casually at a typical bike path speed (10-15mph), and you like the idea of an ebike push up a hill, against the wind or to relieving a sore knee, then your market for a fully legally defined ebike is very broad and your practical use only has a few limitations. Most ebikes will meet your needs and expectation. I would estimate that 85% of the electric bikes on the market are 100% compliant meeting the federal definition. I encourage you to take the plunge and get a good quality ebike and ride more with assist. Do so with the confidence that electric bikes are here to stay. Coexisting with pedestrians and other cyclist will become a normal part of cycling life.