When was the last time you stopped to think about how an electric bike motor works?
The mechanical engineering concepts that power the traditional car also apply to electric bike motors. The only difference is the power source.
How eBike Motors Work: Electric and Magnetic Fields
It has to do with electric fields and magnetic fields. When you close an electric circuit, it allows electrons to move along the wire. This movement generates an electromagnetic field with its own north and south poles.
When you place this close to a nearby magnetic field, you create motion. This motion occurs because of the attraction between opposite poles. It starts with the battery in the ebike connected to the motor. Electrical energy is supplied to the motor via the battery. Read more here.
E-bike motors work by mounting one set of electromagnetics to a second set. Another set of magnets is installed on a housing surrounding the shaft. This is followed by periodically reversing the polarity of one set of electromagnetics.
The ebike motor leverages the attracting and repelling forces to move the ebike. It does so by converting electricity to turn the eBike wheels.
In the case of regenerative ebikes, these magnetic forces transform motion back into electricity.
Read Riding an Electric Bike for the First Time
How eBike Motors Work: AC vs. DC
Electrical supply to our homes arrives as alternating current (AC). It is called AC because the polarity of the power changes several times per second. The United States uses 60-Hz AC (the polarity alternates 60 times per second). Other countries may use 50-Hz AC.
DC enters into and emerges out of the terminals of every battery. Motors need AC to create motion. Without them, the electromagnetic force would eventually achieve equilibrium, and the motion would stop.
This cycle of continually alternating the opposing poles keeps electric bikes in Michigan moving.
DC Motor (Brushed)
These are older motors that generated electricity in the 1900s. DC Current arrives from the battery to the motor vai spring-loaded brushes. These nurses are usually made of carbon or lead. They are used to power the spinning contacts connected to the wire windings.
The windings typically come with permanent magnets. They are affordable, reliable, and provide easy control to alter the speed. Changing the voltage will regulate the speed, while changing the current changes the torque.
The major disadvantages of brushed motors are the lower lifespan and maintenance costs. These motors are not used in most ebikes, except in budget-friendly variations.
Read How Do Electric Bikes Without Pedals Work?
Brushless DC Motor
You can eliminate the hassles of maintenance associated with brushes by switching to permanent magnets. Simply place the electromagnets on the housing. An external motor controller to switch the field windings from positive to negative. This will generate an alternating magnetic field.
The biggest advantages are low maintenance, high efficiency, and a longer lifespan. Brushless DC motors are a bit higher and require more complex motor controllers. These motors are the de facto choice for electric bikes in Michigan. They may also be used in automotive applications such as steer assist.
Read Are eBike Batteries Universal?
How the Motor Interacts with Electric Bikes
All ebikes make use of batteries and motor controllers. The controllers play an important role in regulating the power flowing to the motor. This is used to control the desired current from the battery to the motor.
It is common for ebikes to use a speed sensor (known as the cadence). The cadence works by detecting the rider’s pedaling cadence. The cadence, in turn, senses how much torque is applied to the pedals.
Advanced versions of electric bikes in Michigan come with an option to throttle the speed. This is useful for staying within the city’s speed limits. Or you could use the motor independent of the pedaling.
Make sure to refer to local laws in your state and region about eBike speeds.
Read How to Start an Electric Bike Without a Key
Types of Electric Bike Motors
Although the fundamental concept and technology powering ebikes are the same, there are some differences.
Most ebikes in 2022 are equipped with three different types of motors. Hub drive ebikes have motors inside the front or rear hub. Moreover, there are two types of hub motors. Mid-drive motors are placed at the center of the ebike frame.
Direct drive hub motors have no moving parts. The motor is secured to the frame end and spins around the axle.
You may also find ebike kits that let you equip a regular bike with a mid-drive or hub motor.
Let’s deep dive into the types of eBike motors out there.
Mid-Drive Motors
Mid-drive motors are placed closer to the center of the ebike frame. They transfer power to the rear wheel via the chain drive of the ebike. This allows the motor to supplement your pedaling power.
Most mid-drive motors come with a gear reduction system. This is important because the motors spin several hundreds of times per minute. The motor’s internal gearing optimizes the RPMs to a human-friendly cadence of around 50 to 100 RPM.
Most mid-drive motors also feature gear sensors that cut the motor’s power when changing gears. Several advancements have been made in mid drove motor technology. This results in smaller, lighter, and quieter ebikes.
Most ebikes aimed at hunters are equipped with mid-drive motors. This allows the ebike to be silent while allowing the rider to chase after their prey.
Read How to Take Care of an Electric Bike
Hub Motors
Hub motors are placed in the front or rear wheel hub of the ebike. There are two types of hub motors: Direct drive and geared variants.
A geared hub motor is equipped with planetary gears that reduce the motor’s RPM and increase torque. The problem with geared hub motors is that the ebike doesn’t travel as fast. The Direct drive hub motors have no moving parts.
In general, internal geared hub motors are smaller than direct drive motors. This is because they don’t need to be as large to generate power.
However, the use of planetary gears makes the hubs wider. These motos also come with a freewheel and prevent the bike from using regenerative braking.
Hub motors are often cheaper than mid-drive motors, but they are also less efficient.
Mid Drive Motors: Advantages and Disadvantages
Mid-drives offer more power to cyclists. They allow ebikes to climb steeper hills more efficiently compared to hub motors. This is because they can leverage gear reduction to facilitate low-speed climbing.
The best part about mid-drive motors is that you can easily change the tires. The ebike tires are independent of the motor, and that lets you use any wheelset. This offers users endless customization options.
Mid-drive motors are not without their disadvantages, though. FOr starters, they place a lot of wear and tear on chain-driven eBikes. This means users will have to go for frequent maintenance check-ups to replace worn-out chains.
With that side, high-end mid-drive motors are designed to minimize the stress on chains. Mid-drive motors are often more expensive compared to hub-drive motors. This can drive up the cost of the ebike.
Read How Old to Ride an Electric Bike?
Hub Drive: Advantages and Disadvantages
Hub motors do not wear down the moving parts of the ebike like mid drives. This is because they are placed outside the chain drive. They are also cheaper and can be easily mass-produced in larger quantities. The best part is that manufacturers don’t have to make changes to fit specific motors.
All of this reduces the cost of manufacturing and results in economies of scale. This allows the eBike price to be driven down.
Hub motors are not as efficient when climbing uphill compared to mid-drives. Worse still is the generation of heat due to friction. Climbing uphill at low speeds can lead to heat build-up that can waste performance.
Most hub motors also require more power, and that means bigger batteries. All this adds to the weight of the ebike.
Moreover, the weight distribution in hub motor eBikes is not centered. This effect can be more pronounced depending on the weight of the motor. Finally, it is more difficult to change the tires because they are connected to wires.
You can take the hub-motor-equipped bike to an expert for new tires. This will represent an extra cost.
Aftermarket DIY Motors
Are you good with a wrench? Then you may want to build your own ebike. There are plenty of conversion kits that can be used to convert bikes to ebikes. You can choose the motor, pedal assist, and battery to fit your needs.
Aftermarket kits may require more technical expertise, but they are more affordable. They are great weekend projects that you can work in your garage. Prepare to watch a lot of YouTube tutorials though. Expect a lot of trial and error!
Read Electric Bike Service Costs in the USA
Parts of an Electric Bike Motor
Most electric bike motors use several moving parts, all of which play an important role. Let’s take a look at some of the most important parts.
Motor Controller
Think of the motor controller as the ‘brain’ of the ebike. It regulates the speed and controls the start and stop functions. It is connected to other parts such as the battery, throttle, and motor. The controller’s function is to adjust the power sent to the motor.
They are usually placed close to the base plate of the battery.
Pedal Sensor
The pedal sensor measures the cadence. It often uses several magnets that encircle the spindle. The magnets will pass through the senor during motion and provide pedaling assist.
Display Unit
The display unit is attached to the dashboard of the ebike. It is very similar to the speedometer in automotive vehicles. It communicates with the motor controller to give you information about distance, speed, and battery.
Throttle
Most electric bikes in Michigan feature a throttle mode. When activated, the ebike works very similarly to a motorbike. It assumes control over the ebike and moves it forward. The user does not have to take control of the ebike.
It gives you complete power with no need for pedaling. This is a useful feature if you ever get tired. Throttle mode is usually activated from a button or lever mounted on the dashboard.
Brake
Pulling the level will slow down the ebike by applying friction to the brake rotor. Some electric bikes are equipped with a novel concept called regenerative braking. The spinning wheels turn the electric motor in reverse. This motion charges the batteries.
Although regenerative braking sounds useful in theory, it is not very practical. This is because you need a lot of kinetic energy to recharge the battery. This kinetic energy depends on the mass and speed of the ebike. Most ebikes are simply too small and travel at a very low speed.
Regenerative speed is more useful in larger moving objects traveling at high speeds. Examples that come to mind are cars and trains.
Gear Shifter
Most ebikes feature a gear shifter that is located on the handlebar. The gear shifter is used to switch between gears to adjust power. Lower gears are useful for riding uphill while higher gears are useful for riding downhill.
Read How to Charge an Electric Bike Without a Charger
The Environmental Benefits of eBike Motors
Electric bikes are more environmentally friendly than conventional cars for obvious reasons. They don’t use fossil fuels and some are even equipped with solar panels!
This does not mean that electric bikes are completely perfect. Making the motors and batteries itself generates a lot of pollution. Not to mention the fact that ebikes still use energy that comes from somewhere else.
You may think you are using clean energy. But the electricity may be coming from coal-fired power plants.
In some cases, the power may come from wind turbines or solar panels. If you want a truly environmentally friendly option, you may want to consider regular bikes.
With that said, it would be better for the planet if everyone switched to ebikes.
Wrapping Up
Ebike motors have come a long way with new improvements and enhancements. They control the moving speeds of the ebike and improve your riding experience. As motor technology improves, we’ll see faster, smaller, and energy-efficient variants.
You may like the following electric bike articles:
- Can You Ride an Electric Bike on the Sidewalk?
- Are Electric Bikes Allowed on Bike Paths?
- Can You Use An Electric Bike Without A Battery?
- Electric Bike Keeps Cutting Out
- Will Electric Bikes Get Cheaper?
- How Fast is a 1500 Watts Electric Bike?
My name is Matthew, staying in Seattle, Washington. Electric Vehicles (Electric Cars & Electric bikes) caught my attention for the last few years and my love for electric cars and bikes is everlasting. I spend many of my weekends traveling to various places all over various cities with my electric vehicle (e-bike and electric car). Here I am sharing my expertise, experience, and invaluable information about electric cars and electric bikes. Check out more.