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.
Choose a 36- or 48-volt battery with a capacity of 10Ah or 20Ah. Choose a battery designed for use on an electric bicycle, as it will come with a charger and be much easier to install. Make sure the voltage and capacity of the battery you choose is compatible with the conversion kit you purchased. The higher the voltage of your bike's battery, the more powerful your bike will be. When building an electric bike, choose a 36- or 48-volt battery to allow for speed and comfort.[5]
At the moment this battery is in stock but for local pickup orders only as we are going through the certification testing required for shipping. We've been keeping the 21700 cell offerings on our radar as they start to catch up with the performance specs of the more mature 18650 series and this year it looks like they are finally making the grade. Expect more from us as the year goes on. 
However, laws and terminology are diverse. Some countries have national regulations but leave the legality of road use for states and provinces to decide. Municipal laws and restrictions add further complications. Systems of classification and nomenclature also vary. Jurisdictions may address "power-assisted bicycle" (Canada) or "power-assisted cycle" (United Kingdom) or "electric pedal-assisted cycles" (European Union) or simply "electric bicycles". Some classify pedelecs as distinct from other bikes using electric power. Thus, the same hardware may be subject to many different classifications and regulations.

But in Great Britain, the European Union definition is applicable, and the tighter restrictions of the Electrically Assisted Pedal Cycle Regulations 1983 (including a 200 kg weight limit on solo bicycles) were removed on 6 April 2015 by the Electrically Assisted Pedal Cycles (Amendment) Regulations 2015.[48][49] Riders must be at least 14 years of age, but no driving licence is required.
Some electric bikes claim to use a neat trick called regenerative braking. If you start pedaling the bicycle or going downhill, the spinning wheels turn the electric motor in the hub in reverse and start charging up the batteries. In practice, regenerative braking is nowhere near as useful on an electric bicycle as it is on an electric train or car. An electric bike has much less mass and velocity than either a train or car, so it never gains (or loses) anything like as much kinetic energy when it starts and stops. You'd have to go down an awful lot of hills to charge up the batteries completely and that's usually not practical. And what's the point in pedaling the wheels simply to charge the battery? You might as well have bought an ordinary bicycle to start with!
EU: EN15194 (EPAC – Electrically Power Assisted Cycles) defines the use pedal-assisted less than 25k/h bikes: "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.”

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.

At Volt, when we sell an ebike, we like to keep in touch with our customers. This is not only to find out how their electric bike is performing and if they are happy with it, but also to learn how they use it. Many have impressive stories to tell. We have heard from people using Volt bikes in the most diverse ways and places, from the Scottish Highlands to central London.
Being member of European Economic Area (EEA), Norway implemented the European Union directive 2002/24/EC. This directive defined legal ebikes for all EU and EEA countries to "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.” The definition became part of Norwegian vehicle legislation[17] in 2003. A more detailed specification will become effective when the new European ebike product safety standard EN 15194 is published in 2009.
"Medical Exemptions" are also a standard right in the State of Texas for motorcycles & even bicyclists. Through Texas's motorcycle helmet law (bicycle helmet laws from city ordinances), it is only required for those 21 years old or younger to wear a helmet. However, a medical exemption, [59][60][61][62][63][64] written by a certified licensed medical physician or licensed chiropractor, which exempts one from wearing a helmet, can be used for bicyclists if helmets are required.
The rest of the bike is equally impressive. Integrated lights in the front and the rear run directly off the main battery, so you’re never replacing coin cells or AAA batteries. And the disc brakes give you plenty of stopping power. The 36-volt battery attaches to the down tube and is designed to be easily removed for recharging. A key-lock at the top of the mount ensures that no one can steal your battery if your bike is left in a public place. And a built-in alarm system, activated with a car-like key fob, is ear-splitting enough to keep thieves away altogether. (Miller promises the alarm’s sensitivity is tuned so it shouldn’t go off if the bike is jostled at a public bike rack, but I didn’t have the bike long enough to test this out.)

Oklahoma defines an Electric-Assisted Bicycle in 47 O.S. 1-104 [122] as "Two or three wheels; and Fully operative pedals for human propulsion and equipped with an electric motor with a power output not to exceed one thousand (1,000) watts, incapable of propelling the device at a speed of more than thirty (30) miles per hour on level ground, and incapable of further increasing the speed of the device when human power alone is used to propel the device at a speed of thirty (30) miles per hour or more. An electric-assisted bicycle shall meet the requirements of the Federal Motor Vehicle Safety Standards as set forth in federal regulations and shall operate in such a manner that the electric motor disengages or ceases to function when the brakes are applied."

Photo: Zap Electric's power-assist kit turns a conventional bike into an electric one. There's a bolt-on DC electric motor (weighing just over 3kg or 7lb) just above the back wheel, behind the police officer's foot, pressing against the tire and driving it by simple friction. The motor's powered by a compact lead-acid battery (weighing about 5.5 kg or 12 lb) inside a protective nylon bag. This kit adds quite bit of weight to the bike, but gives extra range and speed when needed. Photo taken in Santa Rosa, California by Rick Tang courtesy of US DOE/NREL.

Beginning January 1, 2017, manufacturers and distributors of electric bicycles will be required to apply a label that is permanently affixed, in a prominent location, to each electric bicycle, indicating its class. Should a user "tamper with or modify" an electric bicycle, changing the speed capability, they must replace the label indicating the classification.
E-bikes use rechargeable batteries and the lighter ones can travel up to 25 to 32 km/h (16 to 20 mph), depending on local laws, while the more high-powered varieties can often do in excess of 45 km/h (28 mph). In some markets, such as Germany as of 2013, they are gaining in popularity and taking some market share away from conventional bicycles,[1] while in others, such as China as of 2010, they are replacing fossil fuel-powered mopeds and small motorcycles.[2][3]

On the other hand, the battery doesn’t lock into the bike, which means you can’t just leave it on your bike when you park at the bike rack. Anyone could walk by and simply remove your battery. That seems like an oversight to me, though perhaps the designers assumed that such a small battery would just be easy to take with you. And it is. My wife could probably lose this battery in her purse.