An electric bike is for all intents and purposes a normal everyday bicycle that has been equipped with an electric motor to assist in its propulsion. These motors are, limited by Federal Law, to 750 watts of power and 20 miles per hour top speed.
Most electric bikes are built to meet that specification but some do exceed them. Electric bicycles can be built from kits for around $500 to $800 dollars or purchased new for between $400 to $3500 dollars. As with any product and especially a vehicle, you usually get what you pay for. Electric bicycles are powered by a rechargeable battery(s), and the average range is around 20 miles. The range can vary greatly depending on the weight of the bike and rider, wheel size, style of riding and terrain. They come in a wide variety of styles and sizes from small electric folding bikes with 16 and 20-inch wheels for commuters and apartment dwellers to 28 inch and 700c sizes. Electric bicycles require no licenses or insurance to operate but many states do have age limitations.
The most common type of motor used in electric bikes is a hub motor. These can be used on either the front or rear wheels and do not require chains, belts or gears. Essentially the motor is the hub of the wheel and contains two concentric rings of opposing electromagnets. When power from the battery is applied to the motor the opposing magnetic force causes the wheel to spin. This type of motor is almost completely silent and requires no maintenance. The higher the wattage of the motor, the more power it provides. One caveat however. There is no standard for measuring wattage. Many marketers of these products use their peak output numbers as opposed to the operating output numbers. A motor rated at 1000 watts peak may be a 500-watt motor in its standard operating output. Be sure to find out which. Only standard operating output is truly comparable. electric bike
Batteries are also very important in regards to these products. The most common battery sealed lead acid (SLA) is the least expensive and provides the highest amp hours (ah). However, SLA batteries weigh three times what a lithium battery does and last less than a third as long. A Lithium LiFePO4 battery is the most expensive battery and has low ah, but is by far the lightest weight and longest lasting. You would have to purchase, install, and dispose of 12 12volt SLA batteries before you come close to the life span of one 48 volt LiFePO4 battery. Nickel cadmium and other batteries fall somewhere in between. A lightweight lithium battery usually slides out of the battery rack for easy recharge indoors rather than having to locate an outlet in which to plug the whole bike. Lithium batteries are by far the most ecologically friendly of all the batteries available.
The electric bikes built from kits are quite often your best bet in terms of price and performance. Most of the bicycles that people already own are superior machines to many of those that have been designed as electric bikes. If you choose your kit carefully you will get a more powerful motor, better battery, and many other features that you cannot find on a factory built bike and your converted bike will often weigh less. A good kit should have the motor pre built into a wheel (a front wheel kit is much easier to install), dual brake motor cutoff, a twist or thumb throttle, a motor controller, wiring harness, and a battery mounting rack with a lock mechanism.
A really good kit will also have wiring diagrams, mounting hardware, wire ties and complete instructions. Very expensive factory built electric bicycles tend to look more like motorcycles, are very heavy and hard to pedal but go no faster or farther than an inexpensive bike or kit built bike. They do look cool though! Also, you will want to purchase your kit from someone who will be able to help you through the installation process in the remote case that you have a question or problem. If you are going to convert your existing bicycle, be sure that it is good operating condition and if you are going to build a bike from a kit of 500 watts or more, use a bike with a steel front fork. Very powerful front wheel motors can pull free from or damage aluminum and suspension forks. You do not require a lot of gearing in an electric bicycle unless you are going to use it as a mountain bike. For street bikes, six or seven gears are more than sufficient. If you choose to buy a factory built bike, find one you able to completely control, feel comfortable riding and that has all of the options you are looking for.