What is Pedal Assist on an eBike and How Does it Work?

Pedal assist is a great feature to have on an eBike. It helps propel you quicker allowing you to ride longer distances with less leg fatigue. There are different types of pedal assist, which we will discuss below. Keep reading to learn more about this great feature!

What is Pedal Assist?

Pedal Assist, in eBike terminology abbreviated PAS for Pedal Assist System, is the term used for the devices that send power automatically to the eBike motor when you pedal. This makes it so you do not have to use a throttle on the handlebars. This system is a response to the speed you are spinning the cranks, the torque applied to the pedals, or a combination of the two.

eBikes with pedal assist systems are sometimes called pedelecs. This system has been around since the 1990s.  The purpose of this system is to make pedaling easier. You can feel it kick in as you move effortlessly propel forward, making it much easier to ride long distances. (Source)

RIDE e MTB Tip: Are you thinking about building an eBike? It isn’t very hard – Heck I’ve got step by step instructions with videos along with all the tools. Check it out 👉 How to Build a Mid-Drive Electric Bike

How Does Pedal Assist Work?

Pedal assist works by using a sensor that essentially talks to the eBike motor. This allows you to ride at your desired speed based on the settings you have on your pedal assist. Pedal assist has two sensor types: cadence and torque.

Cadence sensors turn the eBike motor on when you are pedaling and shut it off when you stop pedaling. The cadence sensor has speed plateaus for each pedal assist setting. For example, pedal assist setting 1 may plateau at 8 miles per hour, while pedal assist caps out at 20 miles per hour. This is the highest speed the pedal assist can achieve on each setting.

Torque sensors are more advanced than cadence sensors. Instead of plateauing based on your pedal assist settings, torque sensors give proportional assistance based on how hard you are pedaling. So, if you pedal faster, the torque sensor sends more power to the motor. (Source)

Pedal assist eBikes have a control button mounted to the handlebars. This allows you to set your assist level so you can decrease or increase the motor power while riding. You only interact with this system if you wish to change the desired assist level.

Ride eMTB Pro Tip: Some bikes only have throttle or pedal assist. Which one is better? Find out in this article 👉 Pedal Assist vs Throttle on eBikes

What Are the Benefits of Pedal Assist on an eBike?

The major benefit of pedal assist is you get power without using the throttle. Using a throttle does not seem like a major hassle, but on long trips or during a stop-and-go commute, having to modulate the throttle to your desired power level can become tiring.

Twist throttles can tire the wrists after long use, and thumb throttles ensure your thumb is constantly extended. Both actions can lead to hand fatigue. Unlike the throttle system, you only engage with the pedal assist buttons if you wish to increase or decrease the amount of assistance while riding.

RIDE e MTB Tip: Check out a complete guide to throttles on ebike 👉 eBike Throttles and How Do They Work

What Are the Drawbacks of Pedal Assist on an eBike?

Some situations pose a danger to you or your eBike while using pedal assist. For example, if you are in a busy city with a lot of stop-and-go traffic, potential obstacles, or low speeds, automatic power whenever you pedal will result in motor bursts. This can cause wear on your motor, which is not what you want. 

If you keep the pedal assist at a lower setting while riding in busy areas, you can reduce the motor bursts and extend the motor life.

What Types of Sensors Does Pedal Assist Use?

There are two main types of sensors for pedal assist on eBikes: cadence sensors and torque sensors. Cadence sensors are the most common type. These involve a magnet ring placed on the spindle or crank arm. The sensor detects the magnet as it goes past when the pedals turn. Other cadence sensors sense passing teeth on the chainring or cog.

Torque sensors measure the amount of force you are applying to the pedals. Torque sensors typically mean replacing the bottom bracket. The new bracket will have a force sensor built into it. Other torque sensor systems measure the force applied to the rear axle, chain, or rear dropout.

The main difference between the two sensors is simply that the cadence sensor does not sense the amount of force applied to the pedals, while the torque sensor does not measure the number of revolutions per minute of the pedals.

RIDE e MTB Pro Tip: With eBikes growing in popularity learning all the terms and definitions can be a bit overwhelming. Let me help with this comprehensive glossary. 👉 eBike Glossary

Can I Add a Pedal Assist System to My Bike?

You can! There are several great conversion kits on the market to turn a recumbent bike into an eBike using pedal assist technology. Many of these are easy to install and integrate into your existing bike model. Some pedal assist conversion kits come with batteries, while others do not.

You need to factor in the range you can get from each battery. A 10-ampere hour battery will give a range of approximately 18 miles (29 km) while an 18-ampere hour battery will give a range of around 33 miles (53 km).

RIDE e MTB Tip: PAS, Throttles and Brakes all work together on an eBike. Read this article to learn more about how eBike Brakes work. 👉 How Do eBike Brakes Work (with sensors)

What is a Good Conversion Kit for Adding Pedal Assist to My Bike?

One of the best conversion kits on the market right now is the Bafang BBSHD 1000W Mid Drive Kit. This kit was designed to fit most bikes including commuter bikes, mountain bikes, road bikes, and fat bikes. The motor that comes with the kit is reliable and powerful. It is brushless and can easily go over 30 miles per hour.

This model is easy to install and comes with all the accessories you need to properly add to your bike. The Bafang BBSHD features cadence sensor pedal assist.

Does Pedal Assist Drain the Battery?

The quick answer is YES. At all pedal assist levels you will use the battery power. But please note the more pedal pressure the rider applies reduces the amount of drain on the battery.

A good rule of thumb is if you think your battery is going to run-out on a ride, start pedaling. Lower the assist level and use some leg power to add range.

Finishing Up

While pedal assist and throttle both have the same function on an eBike, to propel the rider more effortlessly, pedal assist can help keep hand fatigue down. Simply choose the level of assistance desired, and you do not need to push anything else. The only time you interact with the system is to change the assistance level.

In short, pedal assist is a great addition to your eBike!

---