What is a Hub Motor & How Does It Work: Full Guide-FUKUTA ELEC. & MACH. CO, LTD.

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In this article, we’ll explain what is an electric hub motor, how it works, the different types available, and both the advantages and limitations of this innovative technology.

What is a Hub Motor?

A hub motor is a technology that integrates an into the wheel hub itself, which is why it is also called a wheel motor, in-wheel motor, wheel hub motor, or wheel hub drive.
Its clever design even consolidates the power, transmission, and braking mechanisms directly within the wheel, eliminating the need for bulky traditional drivetrains. This simplifies the vehicle’s mechanical structure and enhances efficiency, making it crucial in the development of compact (EVs).
Source: Freepik

The History and Evolution of Hub Motors

The concept of the hub motor dates back to the late 19th century, with one of the earliest patents granted in 1884 to for an electric hub motor designed to power railroad cars and light machinery. A few years later, in 1895, received another patent for an electric bicycle using a front-wheel hub motor, marking one of the first personal transportation applications.
By 1899, , working with the Viennese company Lohner & Co., developed one of the first hybrid electric cars, powered by four battery-driven hub motors combined with a gasoline engine. After that, more early electric vehicles experimented with hub motor designs, but limitations, like added unsprung weight and battery challenges, prevented their widespread use in automobiles.
Still, over time, the simplicity, efficiency, and low maintenance needs of hub motors made them favored in smaller electric vehicles such as e-bikes, scooters, and light mobility devices, especially throughout the 2000s and 2010s. Today, hub motors are widely used in personal electric transportation, while research continues to explore their potential in advanced EV and autonomous vehicle applications.

How Does a Hub Motor Work: Basic Working Principle

• At the heart of the wheel hub motor’s drive technology lies the fundamental principle of electromagnetic induction. The hub motor consists of several key components: , permanent magnets, and a phase controller.

Source: ResearchGate
When the motor receives electrical power, the phase controller, acting as a switching circuit, uses signals from a position sensor to precisely regulate the timing and sequence of current flowing through the stator windings. This creates a rotating magnetic field inside the motor. The magnetic field then interacts with the permanent magnets embedded in the rotor, causing the rotor—and thus the wheel—to spin.
Some manufacturers, like Fukuta Motors, also leverage in hub motors. Hairpin stators use rectangular copper wire to form hairpin shapes instead of traditional round shapes, allowing for tighter winding, improved heat dissipation, and higher power density. This makes hairpin stators preferred for applications that need enhanced space and greater power efficiency.

Functions of the Hub Motor

In addition to generating propulsion, modern hub motors offer multiple functions, including direct driving, load bearing, differential speed control, braking, energy regeneration, and cooling.
Source: ResearchGate

Direct Driving

Unlike traditional that rely on axles and transmissions, most hub motors provide direct driving capabilities by converting electrical energy into mechanical motion. The outer rotor of the motor is connected to the wheel rim, providing smooth and immediate torque to the wheel for vehicle movements.

Load Bearing

The wheel hub connects to the suspension system through the axle bearing, allowing it to absorb road impacts and vehicle loads, all while maintaining alignment between the rotor and stator. This integration helps distribute weight efficiently without interfering with the motor’s operation.

Differential Speed Control

In vehicles with hub motors, electronic differential systems adjust the speed of each wheel independently. For front-wheel steering, the steering gear determines the turning radius, while the rear wheels adjust their rotational speed through electronic control to prevent skidding and maintain optimal traction. This allows for smoother, safer turns without requiring complex mechanical differentials like those found in traditional vehicles.

Braking

Hub motors also support braking system integration by combining both regenerative and friction braking. While regenerative braking handles much of the deceleration, friction braking (typically using disc brakes) provides additional clamping force and ensures safety during rapid or emergency stops.

Energy Regeneration

During regenerative braking, hub motors can switch to energy regeneration mode. The kinetic energy of the moving vehicle is transferred back into the motor, which then operates as a generator. This electrical energy is converted and stored in batteries or supercapacitors for future use. Simultaneously, the motor’s resistive torque contributes to the braking force, enhancing overall energy efficiency and extending driving range.

Cooling

Effective cooling is essential to maintain optimal motor performance and prevent overheating. Hub motors use either air cooling or water cooling. Air-cooled systems often include built-in fans or ventilation structures to circulate air around the motor. Water-cooled systems incorporate dedicated channels that circulate coolant fluid, allowing for more efficient heat exchange and temperature control, especially under high-load or continuous operation conditions.

Types of Hub Motors: 5 Main Categories

Hub motors can be classified into 5 main categories based on their internal design and wheel placement. We’ll introduce these different types of hub motors below to help you find one that is suitable for your performance needs.

1. Brushless vs Brushed Hub Motors

Brushed hub motors use physical brushes and a mechanical commutator to switch current in the motor windings, creating the rotating magnetic field needed for motion. While simple and inexpensive, brushed motors have several drawbacks, including higher power consumption, lower efficiency, and frequent maintenance due to brush wear. Their average service life is also shorter (often around 5,000 hours), and they can be noisier during operation.
In contrast, brushless hub motors (BLDC) replace mechanical brushes with electronic controllers that handle the switching of current. This eliminates friction and wear from physical contacts, resulting in significantly longer service life (typically up to 20,000 hours) and much lower maintenance requirements. Brushless motors are also more energy-efficient, offer higher torque at low speeds, smoother acceleration, quieter operation, and better overall performance. The only downside is that they require more complex control systems and are generally more expensive to manufacture. Despite that, brushless hub motors have become the industry standard for modern electric vehicles due to their advantages.

2. Geared vs Gearless (Direct Drive) Hub Motors

Geared hub motors use a set of internal reduction gears to transfer power from the motor to the wheel. This design allows the motor to spin at a higher, more efficient speed while still delivering strong torque to the wheels, especially at low speeds. As a result, geared hub motors generally offer excellent hill-climbing capabilities. This makes them well-suited for smaller electric vehicles that require efficient power delivery over varied terrain. Nonetheless, because of the additional moving parts, gears may wear over time and require occasional maintenance.
Gearless hub motors, also known as direct drive hub motors, operate without internal gears. Instead, the motor's outer shell rotates directly with the wheel, powered by magnets and coils inside the motor. This simpler construction means fewer parts that can wear out, offering long-term durability and virtually maintenance-free operation. Consequently, gearless hub motors excel in applications where smooth, quiet operation and longevity are prioritized. They are commonly used in larger or high-speed electric vehicles where constant high torque isn't as critical.

3. With Sensor vs Sensorless Hub Motors

Sensored hub motors use built-in sensors (usually Hall sensors) to monitor the rotor’s position in real-time. This allows for precise control of commutation, delivering smooth acceleration, reliable startup torque, and better low-speed performance. Sensored motors are especially beneficial for applications that require frequent starts and stops, such as city commuting or heavy-load transport.
Sensorless hub motors, on the other hand, do not contain position sensors. Instead, they estimate rotor position using back electromotive force (BEMF) generated as the motor spins. While this approach works well at higher speeds, sensorless motors can struggle with accurate positioning at very low speeds due to weak BEMF signals, resulting in less torque during startup. Nevertheless, they have fewer components, which reduces cost and potential sensor failures, making them preferred for light-duty use in recreational vehicles.

4. With Clutch vs Clutchless Hub Motors

Some hub motors use a clutch to disconnect the motor when it’s not powered, effectively eliminating electromagnetic drag. This makes pedaling much easier on electric bicycles when riding without motor assistance. Some clutch systems also allow for gear ratio adjustments, improving efficiency and ride comfort under various conditions.
Clutchless hub motors are directly engaged at all times, which means the motor’s internal resistance is always present, even when unpowered. While simpler in design and typically more durable, clutchless motors may make non-powered riding harder due to the constant drag.

5. Front vs Rear Hub Motors

Front hub motors are mounted in the center of the front wheel. In e-bikes, this placement helps balance the bike’s overall weight, as the motor supports the front while the rider’s weight balances the rear. Front hub systems are also mechanically isolated from the bike’s drivetrain, simplifying installation and maintenance, and reducing interference with gears. However, front hub motors may offer less traction on slippery surfaces since the front wheel generally bears less weight during riding.
In four-wheel electric vehicles, front hub motors can streamline the drivetrain by eliminating the need for a central motor and transmission. They also enable front-wheel drive (FWD) configurations, which are often preferred for their stability, but the four-wheel vehicle may also face similar traction challenges as e-bikes, especially during acceleration or under heavy load.
On the other hand, rear hub motors, positioned in the rear wheel, deliver a sensation of being pushed from behind, which often feels more natural for riders. They typically provide better traction and stronger propulsion, especially on inclines or when carrying heavy loads. Rear hub motors also integrate well with multi-gear drivetrains. Even so, their added weight at the back may affect handling, particularly on rough or steep terrains.
In four-wheel electric vehicles, rear hub motors facilitate rear-wheel drive (RWD) or all-wheel drive (AWD) systems, which are favored for their stronger torque in performance and utility applications. Yet, the increased unsprung mass can affect ride comfort.

What are the Advantages and Disadvantages of Hub Motors?

Advantages of Hub Motors

Hub motors offer various benefits that contribute to their growing popularity in electric vehicles, including:

• Lightweight: The removal of bulky drivetrain components significantly reduces the vehicle’s overall weight. This lighter structure not only enhances energy efficiency but also improves acceleration and overall performance.
• Space Efficiency: With the motor housed inside the wheel, valuable space is freed up within the vehicle’s chassis. This extra space can be used for passenger comfort, cargo storage, or other essential components, as well as additional battery capacity to provide higher power density for a compact design.
• Vehicle Design Flexibility: Thanks to their compact and modular design, hub motors enable manufacturers to easily configure front-wheel, rear-wheel, or all-wheel drive systems, enabling diverse drivetrain configurations. This also allows for hybrid designs by augmenting traditional power plants.
• Quiet and Smooth Operation: With fewer moving parts compared to conventional drivetrains, hub motors operate with remarkable quietness and smoothness, especially with gearless direct-drive systems. This contributes to a more pleasant riding or driving experience, free from the noise and vibrations associated with mechanical transmissions.
• Improved Stability: By distributing weight more evenly and lowering the vehicle’s center of gravity, hub motors contribute to better stability, especially during sharp turns or sudden maneuvers.
• Cost-Effectiveness: While initial costs can vary, the simplified mechanical structure of hub motor systems often translates to lower manufacturing complexity and reduced material requirements. This can lead to more cost-effective production for manufacturers and reduced maintenance needs for users, allowing for long-term cost savings.

Disadvantages of Hub Motors

Now, let’s look at the challenges of using hub motors along with relevant solutions:

• Increased Unsprung Weight in Cars: Installing motors directly on the wheels significantly raises the unsprung weight due to the portion of a vehicle's mass not supported by the suspension system. This can negatively impact ride comfort, handling, and the responsiveness of the suspension system, particularly over rough terrain. Nevertheless, sophisticated suspension tuning and active damping systems can help offset the impact of increased unsprung mass.
• Heat Dissipation and Energy Consumption: Hub motors generate heat during operation, especially during acceleration, braking, or hill climbing, which also raises energy consumption. The confined space within the wheel makes it harder to dissipate this heat, potentially leading to performance loss or even component failure. Manufacturers address this by integrating advanced cooling methods such as liquid cooling systems, improved heat sinks, and high-efficiency thermal management designs. Using high-quality, low-resistance materials further helps reduce energy loss and manage heat more effectively.
• Lower Tolerance in Harsh Working Environments: Because hub motors are exposed directly to road conditions, they face constant vibration, shocks, moisture, dust, and temperature fluctuations. This may accelerate wear and increase the risk of failure. Solutions include robust sealing technologies, corrosion-resistant materials, and reinforced motor housings to protect sensitive internal components. Additionally, regular maintenance or advanced sensor systems are also best practices to monitor motor health and prevent unexpected failures.

Common Applications of Hub Motors

Hub motors are widely used in electric transportation while gradually expanding into industrial equipment and medical devices as technology advances.

E-Bikes and E-Scooters

In electrical bikes and scooters, hub motors are mounted directly in the wheel, simplifying installation and eliminating the need for complex drivetrains. Riders also benefit from steady power, quiet gearless riding, and simple servicing. Some advanced models even combine lightweight design with the hub motor’s inherently strong performance, making them ideal for urban commuting and off-road riding alike.
Source: ResearchGate

Electric Cars

Despite the challenges of added unsprung weight, hub motors are still being actively developed for electric cars. For instance, companies like Protean Electric and Nissan have explored hub motor integration to eliminate traditional drivetrains, offering compact designs and independent wheel control. This allows for potential efficiency gains and simplified power delivery, especially as the automotive industry continues to push for cleaner, zero-emission solutions.
Source: ResearchGate

Industrial and Medical Equipment

Beyond transportation, hub motors serve in industrial and medical equipment requiring compact, quiet, and precise operation. Applications include small-scale automated guided vehicles (AGVs) within factories and warehouses, as well as mobility aids, specialized diagnostic equipment, and even some robotic surgical instruments. This showcases the hub motor’s versatility for precise movement and efficiency in space-constrained environments.
Source: Freepik

The Future of Hub Motors

According to an analysis by , the global hub motor market was valued at approximately $12.26 billion in 2022. This value is projected to grow at a compound annual growth rate (CAGR) of 4.8% from 2023 to 2030, fueled by rising demand for electric vehicles, sustainable transportation, and advances in motor technology.
Looking ahead, future developments in hub motors will focus on creating lighter and more efficient designs. This may include Innovations in materials, such as advanced composites and improved magnetic alloys, which will help reduce motor weight while maintaining or even increasing power output. Enhanced energy efficiency will also contribute to longer range and better performance for electric vehicles and personal mobility devices.
Furthermore, hub motors are expected to expand into a wide range of new applications. Industries such as drones, robotics, automated cargo vehicles, and Internet of Things (IoT) devices are beginning to adopt hub motors for their compact size, precision control, and ease of integration.

Fukuta Motor - Your Best Hub Motors Manufacturer for Innovation

As industries continue to embrace electric mobility and automation, having a reliable hub motor partner becomes more crucial than ever. With this in mind, stands at the forefront of innovation, delivering high-performance hub motors that combine efficiency, durability, and cutting-edge design to meet a wide range of applications.
Ready to power your vision with unparalleled hub motor technology? Explore our or today to learn more about our custom solutions.

FAQs

What is the difference between hub motors and mid-drive motors?

While both are commonly used in e-bikes, the main difference between hub motors and mid-drive motors is their placement and how they transfer power:
Hub motors are integrated directly into the hub of the wheel (front or rear). They provide power directly to the wheel, offering a simple and efficient system with fewer moving parts.
Conversely, mid-drive motors, are centrally located near the pedals or bottom bracket of a bicycle. They transfer power through the bike's chain and gearset, leveraging the bike's existing gears. This can offer advantages in terms of torque for climbing hills and better weight distribution but often involves more complex mechanical components.

Are hub motors AC or DC?

Both AC (Alternating Current) and DC (Direct Current) may be used in hub motors. However, brushless DC (BLDC) hub motors are the most common type in modern electric vehicles due to their simplicity, easy control, and compact size.

Are hub motors reliable?

Yes, hub motors are generally very reliable. With fewer moving parts compared to traditional drivetrains, they experience less mechanical wear and require minimal maintenance. As long as key components like the bearings remain in good condition and the motor is protected from excessive moisture or corrosion, hub motors can last for many years. Their sealed design also helps shield them from dust and debris, making them a durable option for various environments.