E-bike motors - options and their pros and cons

Mid-drive motors are integrated into the frame of the e-bike at the base between the pedals (cranks) as seen in the picture above. This is the most common type of motor in modern pedal-assist e-bikes. They work by transferring power to the bikes drivetrain via the chain to the rear wheel to move the bike forward.

Because they use the e-bikes regular drivetrain and gearing system, they add power very efficiently making cycling uphill easy. They are the go-to motor for e-mountain and off-road e-bikes for this reason.

Mid-drive motors come in different sizes and weights but in general they are quite bulky and make the e-bike look "fatter" than a regular bicycle from the frame. Because of their position on the bike, they lower the e-bikes center of gravity which improves handling and stability.

They also tend to provide quicker response when the motor engages, more torque and power, and the most natural pedaling feel.

Hub-drive motors are located in the wheels of the e-bike inside the wheel hub. They can be located on either the front or back wheel and sometimes in specialized (and usually much more expensive) models on both wheels.

Front hub-drive motors like the one on the e-bike pictured below add weight to the front of the bike which can make the ride feel a bit unnatural. In certain conditions, for example in wet or snowy conditions when riding uphill with the motor engaged, the front wheel might spin.

Rear hub-drive motors usually results in a more balanced weight distribution which can provide smoorther acceleration and more natural feeling when riding. Rear hub motors can also be more easily hidden behind the gears meaning that the e-bike often looks more like a regular bicycle.

There are 2 sub categories of hub-drive motors to be aware of. Direct-drive hub motors and geared hub motors.

Direct-drive hub motors are the simplest e-bike motors. The motor's shaft becomes the axle of the wheel with the motor spinning around the shaft, turning the wheel and moving the e-bike forward.

Direct-drive motors tend to be larger and heavier than geared hub motors as they require more magnetic material to generate torque at low speeds. They are also heavier and are not as efficient at low speeds, for example riding uphill, as geared hub-motors or mid-drive motors.

They are however quieter than geared hub and mid-drive motors although modern geared hub motors are almost silent as well.

Geared hub motors operate like direct-drive hub motors except that inside the motor there are a series of planetary gears that allow it to spin the hub at a lower speed. This means more torque and power at lower speeds but a lower top speed.

Geared hub motors are usually smaller in diameter but wider to fit in the planetary gears. There is also a freewheel inside geared hub motors so they will coast freely when not engaged whereas a direct-drive will have a tiny amount of drag, likely imperceptible to most people anyway.

Long story short, geared hub motors are better for low speed, high torque uses - direct-drive for high speed uses.

The final type of motor available for e-bikes is almost not worth mentioning unless you are looking for a low cost and easy way of converting a traditional bicycle to an e-bike. You will be hard pressed to find a new e-bike for sale with a friction motor.

A motor is bolted onto the bike which drives a small wheel that contacts one of the tires, helping to rotate it using friction.

They tend to be inefficient as a lot of power is lost to friction and heat and they cause increased wear on tires. They are however relatively low cost and can be easily interchanged between bikes.

Although I have outlined 3, there are really 2 option when it comes to e-bike motors today - mid-drive motors between the pedals and hub motors, either direct-drive or geared installed on the front axle, rear axle or occasionally both.

Mid-drive are the most common on modern e-bikes as they are more efficient at different speeds and result in a more balanced bike and a smoother riding experience. They are however louder than hub motors and more expensive and may require more frequent maintenance.

Hub motors are cheaper and are usually found on cheaper e-bikes. They are quieter but often heavier than mid-drive motors and do not usually offer as much torque at lower speeds. They do not require as much maintenance as mid-drive motors but make tyre repair and wheel changes more challenging.