Published on April 18th, 2013 | by Yellow Magpie0
Electric Bicycle Motors: Options For The Electric Bicyclist
Electric Bicycle Motors Photo By Jim Henderson
Electric bicycle motors come in a variety of shapes and sizes from geared to non-geared and hub to non-hub. Here Yellow Magpie takes a look at the different categories and analyses the pros and cons of each type of motor. Hopefully, by the end you will be able to choose an electric bicycle motor that meets your requirements.
Two Types Of Electric Motors
There are two main types of DC motors used in electric bikes – brushed and brushless. Nearly all modern electric bicycles have brushless motors while older models may be brushed. Brushed motors do not need to know the position of the internal magnets and thus can use a sensorless controller. Brushless motors, on the other hand, need to know the exact position of the magnets and require a more complicated sensored controller and hall sensors.
Brushed motors have parts called brushes that eventually wear out. Brushless motors have no parts to wear and provided they are not overheated should last an indefinite period of time.
Electric Bicycle Motors: Geared Versus Direct-Drive
There are two types of electric bicycle motor when it comes to the mechanical application of power – geared and direct-drive. Geared motors are generally smaller and lighter than direct-drive motors. The geared motor spins at a much faster rate. The speed of the motor is reduced by a series of gears that turns the electric bicycle wheel at a more useful velocity.
Direct-drive motors dispense with the geared set-up in favour of having a larger, slower-turning motor that directly rotates the electric bicycle wheel.
Besides the weight differences in practical terms the geared motors are more efficient at accelerating and hill climbing than their direct-drive cousins. This makes them ideal for people who undertake a lot of stop/start journeys. Another advantage of the geared motor is that it offers no resistance when the electric bicycle is pedalled without the motor’s assistance.
Direct-drive motors are more efficient than geared motors on flat terrain and they can take higher temperatures without suffering damage. They also offer regenerative braking capabilities whereas the geared motor, due to its free-wheeling nature, does not. Direct-drive’s major downside is that it is difficult to pedal without any electricity flowing through it as the motor offers resistance.
Electric Bicycle Motors: Hub And Non-Hub
There are two ways of using electric motors in a wheel hub or a non-hub. Electric wheel hub motors are self-explanatory – an in-wheel motor centred around the hub.
Non-hub motors drive chains which in turn propel the bicycle wheel. Non-hub motors allow the electric motor to use the bicycle gears. In this way non-hub, chain-driven motors are far more efficient than hub motors when it comes to acceleration and hill climbing abilities.
The disadvantage of non-hub motors is that they can be very difficult to set-up, are more prone to failure and emit more noise. There are also less efficient overall due to mechanical-energy losses from using an extra chain.
Hub motors, though less efficient at climbing, are overall more efficient, more reliable, plug-and-play and very quiet.
Electric bicycle motors are varied – offering something for everybody. Just pick the motor that has the best characteristics that suit your needs.
Visit Endless Sphere for more information on electric bikes from one of the best internet forums on the subject.
You may like to read Yellow Magpie’s Electric Bicycles: The Electric Revolution For Everyone and Electric Bicycle Components: What Makes Up An Electric Bike.
You may also wish to check out our battery series Lithium Batteries: The Ideal Choice For Electric Bicycles, Electric Battery Terms Made Simple and Future Electric Batteries: The Battery Of Tomorrow.