Electric Motor. Having a battery that will last long is just one piece of the puzzle. The electric motor should be powerful enough to move the bike on flat surfaces without any problems and to overcome some low-steep slopes. It will help you out on steeper slopes, it won’t let you down. If the motor or “the engine” is more powerful you’ll be able to accelerate faster and to reach a higher momentum. This will allow you to reach your destination faster and without you getting tired.
In 2012, two e-bike advocates completed the first 4,000-mile (6,400 km) transcontinental e-bike tour from New York to San Francisco to advocate for e-bikes in major cities across the U.S. Pedego Electric Bikes is the best selling brand in the U.S. Many e-bikes in the United States are standard bicycles converted using a kit. In general, the kits include the motor (the majority of which are hub motors built into the front or rear wheel), a speed controller, throttle (usually twist-grip or thumb throttle), necessary wiring and connectors, and a battery. Several U.S. companies offer conversion kits which also offer advanced lithium battery packs. Major manufacturers also offer complete e-bikes. Trek offers a line of e-bikes using the Bionx system in which the rider programs the controller to determine how much effort the motor will give in response to rider effort, from 25% up to 200% of the rider's power. This system ensures a minimum level of rider participation and is also used to comply with many European laws mandating partial human effort before the motor engages.
Like the Currie, the Rayos has a lot of torque, independent human and electric drive systems, and a drive system that freewheels when not in use. The electronics shut the motor off at 80% battery discharge to avoid a full discharge (which really shortens the life of lead-acid batteries). The Rayos is an 8-speed bike that uses standard bike parts. Seats, handlebars, brakes and other non-electric parts can be found at a supercenter or bike store. Electric parts can be obtained from Rayos dealers.
After you decide which style of e-bike you want, consider the class. In the US, there are three classes defined by the type of assist and how fast the motor will propel you. Most electric bikes sold are class 1 or 3. Class 1 bikes have a motor (max 750w) that assists while you're pedaling, up to 20 mph. Class 3, also known as “speed pedelec” can also have up to a 750w motor, but it can assist you up to 28mph. Both of those are allowed in most states and cities without license. Class 2 have throttles that don't require you to pedal to get a boost. They're allowed on most streets, bike lanes, and paths, but less popular than the other classes and not covered much here (because we still love to pedal and the greater distances pedal assist bikes can cover).