Electric bike kits convert a conventional bike into an electric bike. If you have basic DIY skills or are willing to pay for someone else's skills, you may be able to have an excellent e-bike for less than the cost of buying a complete electric bike.
Many bike shops prefer not to sell, fit, and maintain electric assist kits, because of the easy availability of ready-made electric bikes. But also because not all kits fit all bikes. If you are interested in converting an existing bike into an e-bike, you need to make sure the bike and the kit are compatible a well as make sure that the kit serves your needs.
The two main considerations are kind of obvious when you think about it. To which wheel will the motor deliver the power, and where will you mount the battery?
The most popular implementation is with power to the rear wheel, and the battery mounted on a rear rack.
With power to the rear wheel, the ride seems more natural to cyclists. Rear-wheel drive also accomodates electric-assist technologies conveniently, where the effort of the rider is detected, and a proportional amount of power is sent to the motor.
Front wheel power simplifies the system, because there is no integration with the human-powered part if the drive train. However, front-wheel power is controlled strictly by throttle. (See our Electric Bikes page for more information on rear-wheel drive, front-wheel drive, and crank drive systems.)
Mounting a battery to a rack gets around most issues of individual bike frame geometry. BionX Electric Bike Kits are available with a downtube mounting option that, with a little creativity, can be mounted other places besides a downtube, for recumbents and other non-diamond-frame bikes.
The most common location for a motor is in the hub of the bike -- either the front or rear hub. When you buy an electric bike kit, the entire wheel is usually included, which may limit the selection to 20" 26" and 700c wheels. If your bike wheel is not one of these three sizes, you may need to order just the hub motor (no spokes or rim), and then build (or rebuild) the wheel with the hub motor on your rim. Most bike shops can build wheels.
BionX conversion kits can transform almost any bike into an electric-assist bike. BionX makes several kits to suit your needs for power, speed, range, and weight. Your Bionx powered bike feels familiar, because it's the same bike you had before, but with a natural boost to your own pedal power.
RideKick International make's a trailer that, strictly speaking, is not a conversion kit but can be used on nearly any existing bike -- and provides that extra push cyclists sometimes need when the task, terrain, or weather tempts them to use a car.