Electric Bike Motors Uncovered: Which Motor Is Behind Your E-Bike’s Power?

The concept of electric bicycles dates back to the 1890s, with patents registered as early as 1895. Although technology has advanced significantly since then, the fundamental idea behind e-bikes remains largely unchanged. A crucial component that has evolved over the years is the motor, which plays a significant role in the performance and efficiency of electric bikes.

Brushless direct current (BLDC) motors are the go-to choice for modern electric bikes due to their resilience and efficiency. These motors come in three distinct types: mid-drive motors, geared hub motors, and direct-drive hub motors.

In this article, we will take an in-depth look at the workings of the BLDC motor and explore the various types of motors available. We will discuss their features, how they operate, and the pros and cons of each, to help you understand the differences and make an informed decision.

Which Motor Is Used In Electric Bikes?

Electric bicycles use brushless DC (BLDC) motors. Older models once used brushes to alternate the current, but it was found that brush motors were prone to wear and tear and needed more efficiency. The modern brushless version allows the motor to last much longer and is also a lot more efficient.

Three different electric bicycle motors are currently in use: mid-drive motors, direct-drive hubs motors, and geared hub motors, respectively. Before we look at the three motor options, let’s see how a BLDC motor works.

How Do BLDC Motors Work?

Motors are amazing inventions that create energy. More specifically, magnets are used to turn electrical power into mechanical energy.

A circular arrangement of copper wires wound round poles forms an electromagnet known as a stator. There will also be another circular arrangement of other magnets positioned within the stator or on its outer circumference, comprising the rotor.

The interaction between the stator and rotor through the attraction and repelling of the magnets causes spin. The spinning helps to create torque, which assists when pedaling. What spins will depend on whether it is a hub or mid-drive motor?

On hub motors, the rotor spins, leading to the whole motor spinning and providing torque to the wheel, be it front or back, wherever the hub motor is fitted. Mid-drive motors have the stator attached to a shaft, which is what spins, assisting a chain ring attached to the shaft.

Motors don’t just function independently, and electric bikes will also have batteries and motor controllers. The battery provides the current needed to get the motor spinning while the motor controller controls the power used.

Removable batteries are a lot easier to work with as you can detach and recharge as suits you, whereas built-in batteries will require you to take your e-bike to a charging hub or install one within easy reach. One of the downsides of removable batteries, they are easier to steal.

The Three Different Motors That Are Used In Electric Bikes

Electric bicycles can run on three different sorts of motors. The motors are positioned slightly differently based on how they function. Hub-driven motors are found on the rear or the front hub, while mid-drive motors are located in the middle of the bicycle in the center of the frame.

The Mid-Drive Hub Motor System

Mid-drive systems work more to assist with pedal power instead of pushing extra power. As mid-drive motors function with the spinning of the shaft, the motor is located between the e-bike cranks and adds strength to your chain drive through a chain ring connected to the spinning rod.

As one can imagine, the shaft spins faster than a person can pedal. So, mid-drive systems have an internal gear system that helps to reduce the overall rotations at the shaft, making it rider-friendly.

Pros Of The Mid-Drive Motor System

  • A mid-drive motor provides better overall balance.
  • Mid-drive systems allow for the use of standard wheels, so it’s easier to change your tires.
  • Mid-drive systems provide a quiet motor operation.
  • Mid-drive motors are considered to have higher performance than hub motors.
  • Mid-drive motors are easier to use gear-wise, allowing more torque for hills.
  • Mid-drive use torque sensors for pedal assist in regulating your power based on your pedal power rather than cadence.

Cons Of The Mid-Drive Motor System

  • Mid-drive motors are rough on your drive system, be prepared for damaged bicycle chains.
  • Damaged motors are a lot pricier to replace as the mid-drive motor is built into the bike.
  • Gear shifts can only be made when the e-bike moves, but not if the bike is under motor power, as the chain will snap unless you have gear shift interrupters installed.

The Direct-Drive Hub Motor System

The direct-drive hub motor is the most straightforward of the e-bicycle motors. As the motor shaft does not move, it becomes the axle, with the motor or hub doing the work by spinning on the stationary shaft and powering the bike.

Direct-drive hubs are more commonly placed on the rear wheel, providing the power from behind to propel the bike forward. Direct-drive hubs are larger than geared hubs but narrower. The larger the direct-drive hub, the greater it is capacity to produce higher torque due to increased leverage.

One of the cool things about these motors is that they generate energy when braking, as they are bi-directional. When braking, the power does not stop, but a transfer is made from the motor to the generator, and the braking resistance creates electrical energy. It’s not a lot, but it will help save your brakes when climbing steep hills.

Pros Of The Direct-Drive Hub Motor System

  • Minimal maintenance as these is independent of the drive system.
  • Direct-drive hubs are closed systems with few moving parts, making them less prone to breakage.
  • Direct-drive hub motors are generally a cheaper option.
  • Direct-drive are great for speed over flat surfaces.

Cons Of The Direct-Drive Hub Motor System

  • As the direct-drive hub motor is on the wheel, it can affect the bicycle’s balance.
  • Direct-drive hub motors offer less gear change, and while perfect for flat roads, they only provide a little assistance on hills.
  • Direct-drive hub motors are heavier and can negatively affect your suspension.

The Geared Hub Motor System

The geared hub motor works on the same principle as the direct-drive hub motor, but it includes gears that help to spin the hub at a lower speed, increasing torque but providing a lower overall speed.

The geared hub motors are bulkier in width than the direct-drive versions because the gear parts are included in their construction but are still smaller and lighter.

Pros Of The Gear Hub Motor System

  • Lightweight and small.
  • Geared hubs allow for more torque providing better assistance up hills.
  • Often the least expensive e-bike motor option.

Cons Of The Gear Hub Motor System

  • The geared hub motor could be better for speed.
  • These motors can be noisy.
  • Geared hub motors have more moving parts, requiring more maintenance.
  • Not best suited for heavier riders.

Conclusion

With the rising popularity of electric bicycles and the availability of three different brushless DC motor options, it’s essential to choose the one that best suits your needs. By understanding the unique features and capabilities of each motor type, you can find the perfect electric bike to enhance your riding experience.

Author

  • Miles Baxter

    Miles Baxter is an engineer with a longstanding love for bicycles, sparked by winning a mountain bike in a childhood lottery. Balancing a keen interest in mechanics with the thrill of biking, his career is a testament to the art of turning wheels and gears into adventures.

    Baxter Miles