How Does Pedal Assist Work in Electric Bikes?

Americans are abandoning traditional bikes in favor of electric models at record rates. The reason lies in that satisfying surge of power e-bicycles give whenever you want to pedal with ease, be it a steep hill or a regular ride through busy city streets. It’s all possible thanks to a pedal assist system (PAS), a smart technology that appears confusing to many novice cyclists. Well, it’s not rocket science – we are going to explain what pedal assist is and how it works in simple words.

What PAS Is & How Pedal Assist Bicycles Work

Pedal assist is an operating mode on an electric bike that delivers power when you are riding, like someone is just pushing you along. The system is implemented in the majority of e-bicycles to make cycling easier and more efficient.

Unlike throttle-only e-bikes that let you ride without pedaling (similar to a motorcycle), PAS activates only when you are pushing the pedals. That is, if you start coasting (e.g., down the hill), the assist will cut off, and you will just coast like on a regular 2-wheeled bike. This makes pedal-assist cycles ideal for those seeking a natural riding feel and willing to handle more challenging trips effortlessly without fully relying on the motor.

How Does a Pedal Assist Sensor Work?

A PAS-based electric bike may use a cadence or torque sensor integrated into the drivetrain to deliver power according to the rider’s pedaling input. Here’s how each type of pedal-assist sensor works:

• Cadence sensor: uses a magnetic or optical system mounted near the crankset to detect when the pedals begin to move. So, if you start pedaling, the pedal assist kicks in at your chosen power assistance level and propels you forward at a constant rate, no matter what you are doing (e.g., going uphill or riding on a flat road). As long as you are pedaling, it gives you the same consistent push. Hence, cadence sensors are typically found on recreational and commuter bikes.

• Torque sensor: a more sophisticated sensor system that not only detects when you start pedaling, but also measures how much force you are exerting on the pedals. Unlike the cadence sensor, it adds power in proportion to your riding effort. This means that whenever you start pushing harder, the torque sensor detects this instantly and tells the motor to give you more assistance. Therefore, the system is often used in MTBs and allows for more technical riding.

Now that you know what a cadence sensor is and how torque sensor pedal assist works, it will be easier for you to choose a suitable system according to your needs. Probably the best thing is to try both out to see which one you prefer.

How Much Is a Pedal Assist Bike?

The price for pedal-assist electric bikes typically ranges from $500 to $5,000+, depending on their quality, features, and brand:

• Entry-level e-bikes ($500-$1,500): basic models with cadence sensors, smaller batteries (250-400Wh), and less powerful hub motors (250-500W). They are suitable for casual riders, but may lack durability or advanced features.

• Mid-range cycles ($1,500-$3,000): most popular electric bikes for everyday use. They are equipped with better components like torque sensors, more powerful mid-drive motors (250-750W), and larger batteries (400-700Wh) that can handle 30-70 miles per charge. 

• Premium electric bikes ($3,000-$5,000+): high-end carbon or aluminum models that feature powerful mid-drive motors (500-750W), high-capacity batteries (700Wh+), and torque sensors. These bikes also boast advanced electronics (LCD displays, USB charging ports, etc.).

• Specialty bikes ($5,000+): niche e-bikes with top-tier components, such as Bosch or Shimano systems, and range up to 100+ miles. The most striking examples include cargo electric bicycles, folding models, and high-performance e-MTBs.

How Do eBikes Do Pedal Assist?

An electric bike amplifies the rider's leg input thanks to the coordinated interaction of the motor, sensors, battery, and controller. Here’s how these components work together to detect your pedaling effort and deliver power:

1. The rider starts pedaling. All the magic begins when you start riding, and the sensor system detects pedal rotation (cadence) or measures the exerted force (torque).

2. Sensors send data to the controller. The cadence sensor signals the controller that pedaling has started, while the torque sensor also sends data on the measured force.

3. The controller processes the input. The controller analyzes sensor data and the rider’s chosen assist mode. With cadence sensors, it activates a fixed assistance level once pedaling is detected. With torque sensors, it scales power proportionally to the rider’s effort.

4. The battery powers the motor. The controller signals the battery to send electricity to the motor. The amount of power depends on the chosen assistance level and sensor data.

5. The motor delivers assistance. The motor activates to propel the bicycle forward. Hub motors spin the wheel directly, while mid-drive sets work through the bike’s gears.

6. Feedback and adjustments. Sensors continuously monitor the rider’s performance and send updates to the controller, which adjusts motor output accordingly. For example, if you stop pedaling, the sensors detect this right away and tell the controller to cut motor power.

Also Read: FX-Series 750: Detailed Fat Tire E-Bike Review

How to Easily Build a Pedal Assisted Bike

Building a pedal-assist electric bike involves installing some extra components on a regular bicycle so that it can provide a surge of power when needed. The following steps will help you complete such a DIY project easily:

1. Gather materials. The list includes a motor (hub or mid-drive), pedal assist sensor (cadence or torque), battery and controller, display, and wiring harness. You may also purchase an e-bike conversion kit that already contains everything you need except for the battery.

2. Install the motor. Hub motors are installed on the front or rear wheels, while mid-drive units should be placed into the bottom bracket housing.

3. Install the battery. Mount the battery on the bike frame (e.g., on the down tube) or place it on the front or rear rack if it’s too big to fit well on the frame.

4. Install the sensors. Some sensors already come integrated into mid-drive motors, so no additional installation is needed in this case. If you have a separate sensor, attach it to the crankset or chainring and make sure that it can detect pedal movement.

5. Install the controller and display. If the controller is not built into the battery mount, attach it to the frame near the battery or bottom bracket. The display should be installed on the handlebars so that you can see and use it safely during rides.

6. Connect all cables and test the system. Connect all the components (motor, battery, sensors, and display) to the controller using the wiring harness. At the same time, make sure that no cables interfere with brakes, gears, or pedals. Once done, test the pedal assist system and make adjustments if needed.

How to Increase Speed on Pedal Assist Electric Bicycle

Below, we have highlighted the most efficient ways to make an electric bike faster. However, you should first familiarize yourself with e-bike laws and regulations in your area, as the majority of states limit the maximum speed to 20 mph or 28 mph. If it’s legal, leverage the following tips and strategies to make your e-bike faster:

• Switch to the highest pedal assist mode for maximum motor power.

• Install a more powerful motor of 500W or 750W.

• Replace the battery with a higher-voltage model (make sure it’s compatible with your motor and controller).

• Upgrade your bike with a torque sensor.

• Switch to thinner tires and remove bulky accessories (e.g., baskets, heavy racks) from your bicycle.

• Replace the worn-out components and clean your bike thoroughly.

How to Tell if Pedal Assist Is Working

To determine if the pedal assist system on your electric bike is functioning well, you need to observe how the motor, sensors, battery, and controller work together to give you a boost when riding. Here’s how to tell if pedal assist is working:

• The motor activates when you start pedaling.

• The power delivery is consistent (with cadence sensors), or increases if you pedal harder (with torque sensors).

• The motor stops when you cease to pedal.

• You can see your assist level, speed, and battery status on the display, and the data is updated in real time.

• There are no error messages on the display.

How Many Horsepowers Does an Assisted Pedal Bike Have?

The power of a pedal-assist electric bike is measured in watts and typically ranges from 250W to 750W. You may also find e-bikes with greater motor capacities of 1,000 or more, although they are illegal in the US. These values can be converted to horsepower (HP) for comparison with other vehicles:

• Entry-level motors (250-350W): 0.34-0.47 HP

• Mid-range motors (500-750W): 0.67-1.00 HP

• High-performance motors (1,000W+): 1.34-4.02 HP

How Fast Can You Go On a Bike with Pedal Assist?

Although Class 1 or 2 e-bikes are limited to 20 mph, and Class 3 models – to 28 mph in the US, you can still pedal faster. However, the motor will not help you in this case, as it stops assisting once you reach the designated limit. Consider the factors that influence how fast you can go on a pedal-assist e-bike:

• Motor power

• Battery voltage and capacity

• Type of pedal-assist sensors

• Quality of bike components

• Your physical form

• Terrain and weather conditions

• Bike weight

Rea Also: Navigating Electric Bicycle Trends and Innovations

How to Activate Bike Pedal Assist

Since PAS is designed to engage automatically when you pedal, you will hardly have any problems with its activation. The steps are straightforward:

1. Power on your electric bicycle by pressing the 'ON' button. It’s usually located on the battery, display, or control unit.

2. Choose your preferred assistance level using the display or control unit.

3. Start pedaling, and the motor will activate.

Pedal Assist Sensor Working: Common Issues and Solutions

Since pedal assist sensors are critical components of an electric bike, you should know how to act in case something goes wrong. Therefore, check out the most common issues with cadence and torque sensors, alongside the ways to fix them:

Conclusion

Pedal-assist bicycles are a top choice for those willing to ride smoothly and efficiently without feeling exhausted. By offering a blend of human power and electric boost, these bikes meet all the transportation needs of modern cyclists, from daily commutes to adventurous off-road trips. So why wait? Choose your Avant bike and experience that satisfying surge of power firsthand!