How do electric bike motors work?
In most electric bike drive systems there are 3 main components; the motor, the drive train and the battery. Typically the motor is the most important component in the system. There are 3 different types of motor available on the market and each have distinct features, advantages and disadvantages.
Electric bike motors are often referred to as "hubs" and there are a few different hub types that electric bikes can be fitted with, each have their benefits and drawbacks. We’ll outline the various types below.
Are fitted in the middle of the bike wheel, not changing the basic design of the bike. They are usually fully contained in the motor’s shell within the hub. This style of motor are attached directly to the wheel that they are powering. A geared hub motor of equal power to a direct drive hub motor will tend to be smaller and lighter. Geared hubs can produce greater torque but cannot reach speeds as high as direct drive motors due to a maximum speed that a gear can turn at.
Front Hub: Are mounted to the front wheel of the bike and provide drive and propulsion by spinning the tyre. Because the force is being applied to the front of the bike it feels as though the bike is being pulled along. This can be a strange sensation to get used to for riders who have not ridden an electric bike with this kind of drive system before. Electric bikes with front hub motors can also be balanced differently to traditional bikes and electric bikes with motors located in different areas. These elements will generally only take a couple of minutes to get used to before you are completely comfortable.
Rear Hub: Rear hub motors tend to be more popular than front hub versions. In these cases, the hub is mounted on the rear wheel and provides a driving sensation that is similar to riding a normal bike or motorcycle as opposed to the pulling feeling with a front hub motor. Electric bikes with rear hub motors tend to feel a little more natural in terms of balance too as the majority of the weight is applied towards the rear of the bike.
Direct Drive (crank / mid drive)
Direct drive systems are also referred to as "crank" and "mid drive" motors. This style of hub is mounted in the center of the frame near the pedal hub. Mid drive motors send power to the bike’s drive train as opposed to driving the wheels directly, which makes the drive sensation feel most like a traditional bike. Because they are located in the center of the bike frame they feel the most naturally balanced because the center of the bike is where a rider’s weight is applied. Direct drive hubs tend to lose efficiency on hilly and varied terrain as they are restricted to one particular speed. There are two styles of direct drive hubs, front and rear hubs. There can be a hum associated with direct drive motors because of their engaged moving parts.
Typically, modern batteries can get you between 20-60 miles per charge depending on the rider’s style and riding conditions. Most ebikes will have 3 riding options; pedal only, pedal assist and throttle drive. Pedal only will not engage the motor or battery and will make the bike ride and cycle like a traditional bicycle. Pedal assist mode will be gentler on the battery than purely riding on the throttle and most electric bikes will have levels of pedal assistance you can choose from which can be useful for conserving the battery on long rides. Using the throttle is the least battery efficient mode to ride in as it uses all electrical power and no pedal power.
Electric bike batteries come in a range of voltages usually between 12-36V. With ebikes, you generally pay for what you get so batteries with higher capacities will set you back a little more. The speed your ebike can travel at will depend on the size of your battery, the size of the motor and the level of current that is allowed to pass through the system. Higher current (AMPs) will generally translate into higher speed as more power can be fed to the motor.
This is a crucial part of your electric bike. Without it your bike will be completely unusable. The drivetrain provides the power and torque necessary to move the ebike along. The benefit of mid-drive (geared) hubs is that they supply power directly to the drivetrain. It can be a little easier to change gear on geared hubs than direct drive.
The various ebike drive setups work a little differently and each have their pro's and con's. Ultimately, choosing an electric bike will come down to personal preference and budget.
See the pro's and con's of various ebike motor types