Play it Safe, Make it Easy – E-bike manufacturers will offer you a large variety of styles, types, colors and utility, but the base specifications will be a bike producing less than 750 watts of power (1 horsepower = 746W) , and have its speed limited to 20mph on motor power alone. The majority of US ebikes meet that specification. Manufacturers do this for their own liability. Going this route assures you that your bike was built and sold legally. As a result, you will have about every privilege that a normal bicycle can expect. However, state and local laws may dictate reduced speeds and limited access to bike paths.
Perhaps the cleverest thing of all about the Electric Brompton is that despite all the extra stuff, it folds up exactly the same as the non-powered variety. It's so simple, and unlike certain folding bikes we could mention, what you're left with is a genuinely small thing, rather than something that's about the size of a bike with the front wheel taken off.

Electric-assisted bicycles are treated as human-powered bicycles, while bicycles capable of propulsion by electric power alone face additional registration and regulatory requirements as mopeds. Requirements include electric power generation by a motor that cannot be easily modified, along with a power assist mechanism that operates safely and smoothly. In December 2008, The assist ratio was updated as follow:

Electric bikes vary widely in price, anywhere from $999 to $2000+, so you’ll have to determine how important certain features are to the overall cost. (However, we made a list of electric bikes under $1.000 here.)The battery used to power an electric bike motor is a key factor in how expensive a particular bike is. In general, the more miles a battery can provide, the more expensive it will be, so it’s important to consider the type of riding you plan on doing. If you know you’ll be using predominantly motor-generated power, then paying a bit more for a battery with a longer range is probably a good idea. Alongside with a good quality battery, motor is the most expensive part of an electric bike. Most standard electric bike motors come with a power rating of 250W, and the industry standard in the US is 500W. Maximum power of the motor you can legally use in the US is 750W. The non-electric components used on an electric bike are almost the same with those used on the conventional bicycles. The quality of the components used will affect the maintenance costs of your electric bike down the road, and more quality components mean higher upfront cost. Lastly, there is the frame. Since the frame is basically the skeleton of your electric bike, it’s wise to select a good material that will be the optimum combination of weight and durability.
One of the most important categories of ebikes is the low-cost, entry-level sector. What I call the eBigBox models.  Obviously, not everyone can’t afford a $7500 Riese and Muller and frankly a lot of people are skeptical on how much they will use and enjoy an ebike. So even if they can afford a few thousand dollars for an ebike, they might not want to put it all down on a category they aren’t sure about.
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]
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.
In Norway, e-bikes are classified as ordinary bicycles, according to the Vehicle Regulation (kjøretøyforskriften) § 4-1, 5g. Hence, e-bikes are not registered in the Vehicle Registry, and there is no demand for a license to drive them. Still, there are constraints on the bicycle construction. The maximum nominal motor power output can be no more than 250 watts and the maximum performance speed of the vehicle when the engine is running is 25 km per hour (15 mph).[40] A function that reduces motor power when vehicle speed exceeds 25 km per hour is mandatory. However, if the motor is not running, the e-bike, or any other bike, answer only to the constraints of the ordinary speed limits.
Electric-assisted bicycles are treated as human-powered bicycles, while bicycles capable of propulsion by electric power alone face additional registration and regulatory requirements as mopeds. Requirements include electric power generation by a motor that cannot be easily modified, along with a power assist mechanism that operates safely and smoothly. In December 2008, The assist ratio was updated as follow:
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