How to Choose an Electric Bicycle Motor

electric bicycle motor

How does an electric bicycle motor work? Technological advances in electric motors constantly determine how long, how far and how frequently you can enjoy your ride. There are basically two different kinds of electric bicycle propulsion systems, mid Drives and hub motors. Mid Drives has a huge advantage over their hub-based counter parts in that they use very little power but, unlike hub motors, they are more durable.

Hub Motors

A bicycle parked on the side of a building

A mid-drive motor has a gear in the center that is similar to what you would find on a bicycle, the pedal, to move the rear wheel. This gear ratio actually turns the generator and batteries into a powerful source of electric power that you then use to power the drive system of your electric bicycle. This is known as a “Pedal Ahead” drive system.

Hub motors are a little more complex. They have two drive elements. One is the central shaft and the other is the wheel axle. The central shaft is connected to the drive wheels on the front end of the bicycle. The wheel axle is connected to the back wheel and the generator is connected directly to the axle.

Size Of The Motor

A bicycle parked on the side of the railing

When selecting a bicycle motor, you will need to consider the size of the motor, the horsepower rating, the torque and the power rating of the motor. The size of the motor will be dictated largely by the size of the bicycle itself. The horsepower rating is usually based upon the weight of the rider and the total amount of power required to propel the bicycle uphill. The torque is measured in horse-power (watts) and is equal to the force exerted upon an object at the speed the motor is operating at. And finally, the power rating is simply expressed as a measure of the amount of energy that the motor requires to complete the necessary task.

There are three main categories of electric bicycles – those powered by the wind, those powered by the electric motor and those that are propelled solely by the batteries. The type of motor you need will depend largely on the kind of drive system that you have selected for your electric bicycle. The most popular drive system is the windmill drive. The main reason for this is that it is very efficient and allows the user to ride with no wind resistance even on flat terrain.

Electric Motor

The second most common drive system used in electric bicycles is the electric motor. An electric motor is commonly mounted to the rear of the bicycle. The motor must be powerful enough to propel the bicycle over even moderate hills. Because the motor requires a considerable distance to charge it, the speed at which it can operate must be considered when determining its horsepower. Finally, to be able to propel a bicycle over hills the motor must be powerful enough to use the available torque.


Another important consideration is the wattage of the batteries that you use. Be careful not to select a motor that is too small. If it is, your electric bicycle will have trouble starting. And if it is too large, it will be very hard to propel the bike over difficult terrain.

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