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How Does an E-Bike Motor Work?

Over the past few years, e-bikes have gained a lot of popularity. These bikes are probably the most significant green transportation adoption in the world. They are emission-free and noise-free.

The rider gets to decide whether he wants to pedal fully, partly, or move on throttle mode. This provides the rider with a lot of flexibility to choose his own pace and take breaks whenever required.

The bike’s motor enables forward propulsion. One can quickly reach up to 25 miles per hour and have an effortless riding experience.

How do E-Bikes Motors work?

There is a whole lot of internal mechanism which provides the rider with an effortless riding experience. E-bikes essentially consist of highly integrated power motors.

In most bikes, the motors used are brushless DC motors or BLDC motors to overcome the limitation of wear and tear that earlier motors used to face. The working of these motors involves understanding some mechanical concepts.

For instance, if you ever happen to open up a BLDC motor, you’ll observe how a big bunch of wires is wound around a circular pole. This setup comprising the cables around the pole forms the “Stator.”

This stator acts as an electromagnet when the motor controller draws current from the battery. This current directly gets transmitted to the wires.

The stator consists of several permanent magnets arranged in different orientations either inside or outside the stator. This is known as the “Rotor,” and the orientation depends on the BLDC motor type.

The constant flow of current from the stator’s electromagnet causes the permanent magnets to attract and repel alternatively. This mechanism causes them to spin.

The process of generation of torque is different for various motors. While the mid-drive motor utilizes the shaft’s spinning mechanism for the torque generation, the hub motors don’t have a mechanism where the shaft spins.

Instead, the rotor spins and creates torque to spin the front or rear wheel.

How Does An E-Bike Hub Motor Work?

Some e-bikes consist of direct-drive hub motors, which are more straightforward. These motors have a slightly different working mechanism.

Unlike the BLDC motors, here, the shaft doesn’t spin. It acts as a rear axle instead. The shaft remains fixed in a place, and the rotor or the hub spins around the shaft.

This causes the motor to propel the rider in the forward direction. These motors are bi-directional and generate some electrical energy when the rider applies brakes. This is also known as “Regenerative Braking.”

The rider can move forward as well backward with a lot of ease. When the brakes are applied, the motor controller becomes a generator when indicated by a cutoff switch.

This resistance gives rise to electrical energy, which tends to be beneficial in the long run as the braking energy doesn’t get absorbed through friction.

Pros:

  • These motors are designed for high-speed riding.
  • They have a regenerative braking mechanism, which causes less wear and tear.
  • These motors operate in a much quieter manner than the geared ones.
  • These motors can easily handle higher speeds and power without becoming overstressed.
  • They are manufactured in a massive range and are thus cheaper.

Cons:

  • Direct drive motors have a bigger and bulkier design.
  • They provide only minimal coasting resistance.
  • These motors are not suitable for uphill cruising.

How Does An E-Bike Geared Hub Motors Work?

The direct-drive hub motors discussed above have a bigger diameter than the geared hub motors. Thus the performance, as well as the internal mechanism, varies slightly.

The geared hub motors consist of an electric motor that spins at a very high speed. Here too, the shaft doesn’t spin.

As the name suggests, the geared hub motors have various gears. Thus, the shaft gets connected to these planetary gears in a series connecting to the hub.

This causes the hub to spin at a much slower speed, but this results in greater torque. These motors’ diameter may be smaller, but various planetary gears make the hub look wider in size.

The geared hub motors don’t work on the concept of regenerative braking. Instead, they consist of a freewheel, which gives rise to free “Flow Braking.”

Pros:

  • As compared to the direct drive motors, these motors are better when it comes to riding at a low speed.
  • These motors also enable the high-torque application.
  • They have higher internal RPM.
  • These motors coast with less resistance, making the rider feel like riding a traditional bike.
  • The helical-cut motors have a subtle design.

Cons:

  • These motors are not suitable for high speeds.
  • These motors are more prone to wear and tear due to the absence of regenerative braking.
  • Apart from helical-cut motors, all other geared hub motors make a lot of noise.

How Does An E-Bike Mid Drive Motors Work?

Mid-drive motors are located between the electric bike cranks and are thus closer to the bike center. In simpler words, the mid-drive is positioned between pedals at the bike’s bottom bracket.

They work on the mechanism of transferring the power to the rear wheel via the chain drive.

Correspondingly, the electric motor actively generates a torque, making the shaft connected to the chain drive spin.

Hence, when the rider pedals, there is no additional power source to supplement the pedaling activity. The motor also has a “Gear-Reduction” system, optimizing the biking performance by limiting the shaft’s RPMs.

This motor enables the riders to ride long distances on a single charge.

Pros:

  • These motors provide a more extended riding range on a single charge.
  • They are designed for climbing uphills and leisure cruising.
  • They make use of higher gear reduction for low-speed climbing.
  • Changing tires of the bikes, which consist of mid-drive motors, is much more comfortable.
  • The rider can run any wheelset because the frame and the hub don’t have any wirings between them.
  • As this motor is placed nearer the bike center, the rider experiences a more balanced ride.

Cons:

  • The mid-drive motor essentially operates on the chainring. This causes frequent wear and tear to the chain.
  • The added torque also causes chain wear, which might require the user to replace it more often.
  • These motors are expensive as they consist of several mechanical components.

FAQs

What is better, mid-drive, or hub drive motor?

The traditional hub motors provide less power than the mid-drive motors. Mid drives give multiplied power and, subsequently, high performance.

How long do Hub Motors last?

The electric bikes, which consist of a direct drive hub motor, generally last up to 10,000 miles or sometimes even more. The hub motors have a long life and tend to be reliable.

What is the advantage of hub motors?

Hub motors cut mechanical losses and provide an enhanced riding experience as they have a quiet design and ensure regenerative braking.

Conclusion

E-bikes are the future. These bikes are mindfully designed, and different bikes consist of different types of motors. Every motor has its pros and cons. Some of these motors enable high-speed riding, whereas some ensure higher torque generation but lesser speed.

 

Written by Lee Hill

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