The Espin is powered by a 350-watt motor that’s rated for trips up to 50 miles (depending on the terrain and assist level). Once depleted, the battery fully charges in roughly five hours. Thankfully, Espin makes it easy to remove the battery, allowing you to quickly recharge it at home or in the office between trips. A backlit LCD control hub displays your basic metrics and battery life while in transit and LED headlights add a touch of light when needed.
Many newer or smaller companies only design and market their products; the actual production is done by Asian companies. For example, some 60% of the world's bicycles are now being made in China. Despite this shift in production, as nations such as China and India become more wealthy, their own use of bicycles has declined due to the increasing affordability of cars and motorcycles.[102] One of the major reasons for the proliferation of Chinese-made bicycles in foreign markets is the lower cost of labor in China.[103]
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.

Vehicles with an electric power and power of less than 300W are classified as "not a motor vehicle". Such electric bicycles must comply with the same rules as bicycles. You must wear a helmet even on a scooter or bike under 300W. If the power is over 300W or a combustion engine is used it is a "low powered vehicle" and the moped rules apply. Specifically, a drivers license and registration are required.
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.
When I began testing the Rad Power bike, I wasn’t sure if it would ride like a bakfiets or more like your standard bike. Hundreds of miles later, the RadWagon’s biggest strength is how well it handles. If you aren’t riding with kids, you almost never notice the weight of the cargo area behind you and pedaling is made easy and efficient thanks to a 750W direct drive hub motor and smooth acceleration.
© 2019 Condé Nast. All rights reserved. Use of and/or registration on any portion of this site constitutes acceptance of our User Agreement (updated 5/25/18) and Privacy Policy and Cookie Statement (updated 5/25/18) and Ars Technica Addendum (effective 8/21/2018). Ars may earn compensation on sales from links on this site. Read our affiliate link policy.
First, think about what you need your bike for -- if it's just for a short city commute, in among traffic, then consider a smaller frame that's easy to manoeuvre through cars. The GoCycle G3 (right) is impressively nimble and its electric assistance will help propel you up to 15 mph (24 kph). Better yet, it has built-in lights, automatic gears and you can customise the amount of power the motor provides using a phone app. 

You can learn more about the development and axle testing process on this endless-sphere thread. Our ambition is to make this splined axle design into a new standard that we deploy across our entire higher power motor lines to replace axle flats. If you're as excited as us and want to jump right into ordering, we have the first production shipment on hand available in bare motors and complete kits.
There are individuals who claim to have lost considerable amounts of weight by using an electric bike.[62] A recent prospective cohort study however found that people using e-bikes have a higher BMI.[63] By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able.[64] This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer. [1]
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:
×