top of page

How Does An Electric Bike Work?

Electric bikes, or e-bikes, have revolutionised the way we commute, combining the convenience of traditional bicycles with the efficiency of electric propulsion. In this article, we’ll delve into the fascinating world of electric bikes and uncover how an E-Bike works!

How does an electric bike work?

What Makes An Electric Bikes Work?

The Heart of the E-Bike: The Motor

At the core of every electric bike is an electric motor. Typically located in the hub of the front or rear wheel, or integrated into the bike frame, this motor is responsible for providing the extra push needed for a smoother and faster ride. E-bike motors come in various types, the most common being brushless DC motors for their efficiency and durability.

E-Bike Motor

The motor in an electric bike serves as the powerhouse, providing the necessary propulsion to assist or fully replace the rider's pedalling effort. The basic principle involves converting electrical energy from the bike's battery into mechanical energy, which drives the wheels. Here's a breakdown of how the motor in an electric bike works:

  1. Types of Motors:

  • Hub Motors: These motors are located in either the front or rear hub. They are divided into two main types: geared and direct drive (gearless). Geared hub motors use internal gears to reduce motor size and weight, while direct drive motors have a larger diameter and operate without gears.

  • Mid-Drive Motor: Positioned at the bike's crankset (where the pedals connect), a mid-drive motor directly powers the bike's chain. This design utilizes the bike's gears, providing better torque and efficiency, especially on varied terrain.

  • Rear Hub Motors: These are positioned at the rear of the bike and are one of the most common places for an e-bike motor. Although the motor position doesn't affect how much power output a motor gives out, the placement of a motor system comes down to personal preference.

  1. Power Source:

  • The electric bicycles power source is a rechargeable battery, typically lithium-ion. The battery stores electrical energy and is mounted on the frame, often in the downtube or rear rack. The voltage and capacity of the battery influence the motor power and the bike's range.

  1. Controller:

  • The controller is the brains of the electric bike's motor system. It regulates the flow of electrical energy from the battery to the motor, controlling the speed and power assistance levels. Riders can usually adjust these levels using a control interface on the handlebars.

  1. Sensors:

  • Electric bikes are equipped with sensors that detect the rider's pedalling and adjust the motor's assistance accordingly. The main types of sensors are:

  • Pedal Assist Sensor (PAS): Monitors the rotation of the pedals and adjusts the motor assistance level based on the rider's pedalling effort.

  • Torque Sensor: Measures the force applied to the pedals, providing a more natural and responsive assistance based on the rider's exertion.

  • Cadence Sensor: Tracks the speed at which the rider is pedalling and adjusts the motor assistance accordingly.

  1. Operation Modes:

  • Electric bikes typically offer different operation modes, allowing riders to choose the level of motor assistance or use the bike purely as a conventional bicycle. Common modes include:

  • Pedal-Assist (PAS): The motor provides assistance when the rider pedals.

  • Throttle Control: Riders can use a hand throttle to control the motor without pedalling (common in Class 2 e-bikes).

  • Manual Mode: The motor is turned off, and the bike is solely pedal-powered.

  1. Regenerative Braking (Optional):

  • Some electric bikes feature regenerative braking, which harnesses energy during braking and feeds it back into the battery. This system enhances energy efficiency and may slightly extend the bike's range.

  1. Safety Features:

  • Electric bike motors often come with safety features, such as automatic cut-offs when a certain speed is reached, ensuring compliance with local regulations.

In summary, the motor in an electric bike works by converting electrical energy from the battery into mechanical energy to assist the rider's pedalling effort. The integration of sensors, controllers, and various operation modes enhances the overall efficiency and adaptability of electric bike motors, providing a versatile and enjoyable riding experience.

Power Source: The Battery

The power for the electric motor comes from a rechargeable battery pack. These batteries, often lithium-ion, are lightweight and capable of storing a significant amount of energy. Mounted on the frame or integrated into it, the battery is a crucial component determining the range and performance of an e-bike.

E-Bike Battery

Electric bike batteries serve as the energy storage unit, supplying power to the electric motor that propels the bike. Understanding how an electric bike battery works involves grasping the basic principles of energy conversion and storage. Here's a breakdown of the key components and processes:

  1. Battery Chemistry:

  • Most electric bikes use lithium-ion (Li-ion) batteries due to their high energy density, lightweight, and long lifespan. Within the battery, there are positive and negative electrodes, typically composed of lithium cobalt oxide (LiCoO2) for the positive electrode and graphite for the negative electrode.

  1. Cells and Pack:

  • A typical electric bike battery is composed of multiple individual cells connected in series or parallel to create a battery pack. Each cell has its voltage, and combining them into a pack increases the overall voltage and capacity. The pack is enclosed in a protective casing, usually mounted on the bike frame.

  1. Voltage and Capacity:

  • The voltage of an electric bike battery is a crucial factor influencing the motor's performance. Common voltages range from 24V to 48V, with higher voltages generally providing more power. Capacity is measured in ampere-hours (Ah) or watt-hours (Wh) and determines how much energy the battery can store. A higher capacity usually results in a longer range.

  1. Charging and Discharging:

  • When charging, electric current flows into the battery, causing lithium ions to move from the positive electrode (cathode) to the negative electrode (anode). During discharging, such as when powering the electric motor, the process reverses, with lithium ions moving back to the positive electrode. This flow of ions generates an electric current that powers the motor.

  1. Battery Management System (BMS):

  • The Battery Management System is a crucial component that monitors and manages the individual cells within the battery pack. It ensures balanced charging and discharging, prevents overcharging or over-discharging, and safeguards against overheating. The BMS contributes to the overall safety and longevity of the battery.

  1. Charger:

  • The charger is responsible for replenishing the energy in the battery. It converts household AC power to the DC power required by the battery. Most chargers are equipped with safety features and automatic shut-off mechanisms to prevent overcharging.

  1. Range and Riding Conditions:

  • The range of an electric bike, or the distance it can travel on a single charge, depends on various factors, including battery capacity, riding conditions, rider weight, terrain, and the level of motor assistance. Manufacturers often provide estimated ranges based on optimal conditions.

  1. Lifespan and Degradation:

  • The lifespan of a lithium-ion battery is influenced by the number of charge-discharge cycles. Over time, the battery's capacity may degrade, leading to a reduction in range. Proper charging and storage practices, as well as the quality of the battery and its management system, contribute to the overall longevity.

Understanding how the battery in an electric bike works provides insight into the key elements that power the electric motor and drive the entire e-bike system. Regular maintenance, proper charging practices, and adherence to manufacturer guidelines are essential to maximize the lifespan and performance of an electric bike battery.

Pedal Assistance: Pedelec System

Unlike electric scooters or mopeds, e-bikes are designed to be pedal-assist. This means that the electric motor kicks in to provide assistance only when the rider is pedalling. This pedelec system ensures that the e-bike experience closely mimics traditional cycling while offering a boost when needed, promoting a more active and engaging ride.

E-Bike Pedal Assist

A Pedelec, short for "Pedal Electric Cycle," is a type of electric bike equipped with a pedal-assist system. This system is designed to augment the rider's pedalling effort rather than replacing it entirely. Here's how the Pedelec system works on an electric bike:

  1. Pedal-Assist Sensor (PAS):

  • The heart of the Pedelec system is the Pedal-Assist Sensor. This sensor is typically integrated into the bike's drivetrain, near the bottom bracket or within the crankset. The PAS detects the rotation of the pedals and measures the speed at which the rider is pedalling.

  1. Torque Sensor (Optional):

  • Some advanced Pedelec systems may include a torque sensor, which measures the force applied to the pedals. This additional sensor provides a more natural and responsive assistance level based on the rider's exertion.

  1. Controller:

  • The Pedelec system is connected to a controller, which is responsible for interpreting the signals from the PAS and, if present, the torque sensor. The controller adjusts the level of assistance provided by the electric motor based on the rider's pedalling input.

  1. Electric Motor:

  • An electric motor is integrated into the bike, often in the hub of the wheel or, in the case of mid-drive systems, near the bike's crankset. The motor is connected to the controller and receives commands to provide additional power when needed.

  1. Battery:

  • The electric motor is powered by a rechargeable battery mounted on the bike. The battery supplies the necessary electrical energy to the motor. Common battery types are lithium-ion (Li-ion), known for their high energy density and lightweight properties.

  1. Pedal-Assist Modes:

  • Pedelec systems usually offer multiple assistance modes that riders can select based on their preferences or the terrain they are navigating. These modes may include:

  • Eco Mode: Minimal assistance, conserving battery power for longer rides.

  • Standard Mode: Moderate assistance for a balanced riding experience.

  • Sport/Turbo Mode: Maximum assistance for tackling hills or accelerating quickly.

  1. Seamless Assistance:

  • When the rider starts pedalling, the Pedelec system engages the electric motor to provide assistance. The level of assistance is determined by the selected mode and the rider's pedalling input. As the rider increases their pedalling effort, the motor responds by delivering more power, creating a seamless and natural riding experience.

  1. Automatic Cut-Off:

  • Many Pedelec systems include an automatic cut-off feature that stops motor assistance when a certain speed is reached, often in compliance with local regulations. This ensures that the e-bike remains within legal speed limits.

  1. Regenerative Braking (Optional):

  • Some Pedelec systems may feature regenerative braking, where the motor acts as a generator during braking, converting kinetic energy back into electrical energy to recharge the battery slightly. While not present in all systems, regenerative braking enhances overall energy efficiency.

In summary, the Pedelec system on an electric bike enhances the riding experience by seamlessly integrating electric assistance with the rider's pedalling effort. The system's sensors, controller, motor, and battery work together to provide a natural and efficient cycling experience, allowing riders to navigate various terrains with ease. How much assistance and the pedal power output you require however is completely up to you!

Control and Connectivity: E-Bike Controller

The e-bike controller acts as the brain of the system, regulating the flow of electricity from the battery to the motor. It also allows riders to control the level of assistance, adjusting the power output based on their preferences or the terrain they’re navigating. Some advanced controllers even come with connectivity features, allowing riders to monitor and customize their e-bike settings through smartphone apps.

Regenerative Braking: Efficient Energy Use

Many e-bikes incorporate regenerative braking systems. When the rider applies the brakes, the electric motor switches to generator mode, converting kinetic energy back into electrical energy and storing it in the battery. This feature enhances the overall efficiency of the e-bike and extends its range.

The Display: Information at Your Fingertips

Modern e-bikes are equipped with user-friendly displays mounted on the handlebars. These screens provide essential information such as speed, battery level, distance travelled, and the selected assistance level. Riders can easily monitor their e-bike’s performance and make informed decisions during their journey.

In conclusion, the magic of an electric bike lies in its seamless integration of traditional cycling with cutting-edge electric propulsion. The combination of a powerful motor, high-capacity battery, intuitive controls, and smart features makes e-bikes a popular choice for commuters and recreational riders alike. As technology continues to advance, we can expect even more innovations in the world of electric bikes, further enhancing the riding experience and contributing to a greener and more sustainable future.

Recent Posts

See All


bottom of page