Ebike Motors and Technology, Compared and Explained

By Jordan Galeles

A cyclist new to e-bikes probably has a few questions about what e-bike motor they should get. This article will cover the ins and outs of e-bike motors to help cyclists make an educated decision for an e-bike that will best suit their needs.

Types of E-bike Motors

Hub Motors

Hub motors are generally a better fit for commuters or those looking for basic assisted cruising.

Hub motors can be mounted on either the front or rear of the bike. Rear hub motors will mount more securely and have better traction than front hub motors. Installing the hub motor on the front wheel may save you time when it comes to rear tire changes, since rear tires will be battered more than front wheels from regular debris, but it may feel like you’re being pulled along instead of propelled.

Pros: Hub motors require little maintenance since all their components are within the casing and can more easily be replaced.

Cons: A hub motor will have wires attached to the bike to power and control the motor, which will make it more difficult to change tires. Usually, hub motors will use cadence sensors that monitor motor power based on pedal speed, so it’s less accurate and can result in choppy response time during high demand and maneuvering. They aren’t very good for ultra-hilly treks (though they can deal with regular, not-too-steep hills just fine) and are a little heavier than mid-drives.

Geared hub: Geared hub motors are generally lighter than direct drive or “gearless” hub motors, so commuters will appreciate not having to haul something heavier around.

Gearless/direct drive hub: If you’ve already decided on a hub motor and you’re looking for power and willing to have a heavier bike, direct drive hub motor is the way to go.

All-in-one wheel motors: They take less time to install because the battery is packed in the middle of the motor casing. Because of the limited battery size, they tend to have very low power and range, so good for short trips and flat street riding, but that’s about it.

Mid-drive Ebike Motors

Mid-drive motors best serve cyclists looking to take on rough terrain, or who want a more well-engineered ebike designed around the motor.

Pros: Mid-drive motors will more easily respond to changes to torque measured at the crank since they can use sensors for pedal assist that regulate motor power. Regular tires can be used and changed with ease while using mid-drive motors. Mid-drive motors are lighter and can tackle hills and shift gears with more power and ease than hub motors. Because mid-drive motors are installed where the pedal crank meets the frame, they tend to feel like a more natural ride.

Cons: Mid-drive motors tend to be on the pricier side compared to hub motors, due to increased gear reduction and mechanical components. For the same reason, as with all mechanical systems, the more components involved, the more likely something is to break, so mid-drive motors will typically need more maintenance than hub motors. High on the maintenance list for mid-drive bikes are replacing bike chains. Regular chains just don’t have the capacity for continuous 250-750 W output, so most retail mid-drive bikes will include a chain designed specifically for e-bikes that can handle the extra torque. Belt drive instead of chain drive will also resolve that issue.

Friction Drive Motors

Friction drives function using a more simplistic method than hub or mid-drive motors. They generate power through friction from a wheel that presses against the tire. The friction element diminishes during wet weather, so it’s not as effective in those circumstances. They often tend to be less aesthetically pleasing compared to hub or mid-drive motors which usually blend into the frame.

E-bike Battery & Power

Another thing to keep in mind is the balance between performance and ride duration. You’ll usually want to decide if you’re looking for extended battery life (measured in watt hours, Wh) or more motor power (measured in watts or horsepower), because you’ll likely sacrifice one for the other. The more power you have, the more it will drain your battery’s juice.

There are many factors that affect ride duration, such as elevation changes, weight, and pedal cadence, so you’ll want to keep those things in mind and potentially keep an extra battery charged and on hand in your pack if you’re planning on taking a lengthy trip.

Explanation of E-bike Classes

Many states have implemented a 3-class regulation model that breaks down e-bikes into three categories based on speed, power, and level of assistance. The three classes of e-bikes are: Class 1, 2, and 3. These classes were implemented by California in 2015, and because this 3-class model hasn’t yet been adopted in all places, there is a need for more clarity in regards to e-bike classification nationwide.

Class 1 is most popular with newer e-bike riders. The motor in class 1 bikes activates through pedaling and deactivates once cyclists reach 20mph. Class 1 bikes are generally accepted on any paved surfaces that a regular bike is allowed and are usually most affordable.

Class 2 is like class 1, but also has a throttle-assist in addition to pedal assist up to 20mph. Class 2 bikes are banned in some places due to the throttle assist, which is used similarly to the throttle you’d find on a motorcycle to propel your bike.

Class 3 provides pedal assist like class 1 but continues to 28mph instead of stopping at 20mph. Lastly, class 3 bikes are a little pricier and not typically allowed on most paths or mountain bike trails but are allowed on most city streets. Class 3 bikes also have more speed and power for hills, stops and starts, and hauling so it’s popular with commuters. On paper, by law in California, class 3 bikes can only be ridden by those over 16 years of age and riders must wear a helmet. Class 3 bikes tend to be a controversial class because they are sometimes restricted from shared-use paths like in parks where they are used by both cyclists and pedestrians.

While laws have been implemented in California, many states and cities are still ironing out the details of how they plan to implement e-bike classes. People for Bikes provides a state by state e-bike policy guide here: https://peopleforbikes.org/our-work/e-bikes/policies-and-laws/.

Where Are Ebikes Allowed or Banned?

The classification system has helped better define e-bikes and where they can go, but it hasn’t resolved some core issues, especially when it comes to electric mountain bikes (eMTBs), federally managed trails, and the opposition from numerous conservation groups.

There’s a chance EMTBs with throttle-assist may damage trails. There’s also the potential issue of policing e-bikes on trails with resources not designed or allocated for e-bikes. Some fear motorized bikes will bring raucous noise to peaceful trails. Some think the paths, trails, and tracks will get just plain crowded with e-bikes allowing more people to go more places. Others without vehicles may fear the risk of injury from being impacted by an e-bike in a space where they were previously absent. Lastly, and perhaps the most common fear of bringing e-bikes to non-motorized paths and trails, is how do you draw the line between e-bikes and motocross-style bikes? (The implementation of the 3-class model greatly helps with this.)

On the other hand, while there are plenty of motorized roadways for travel, cyclists of eMTBs seek more single-track backroads recreation, which is in short supply for motorized bikes as they are typically reserved for non-motorized vehicles. Separately, there’s very little need to fear extra noise from e-bikes, as most e-bike motors are whisper-quiet – often no different from the noise of a regular bike. (Those with conversion e-bike motor kits installed on the front wheel should be aware that it may cause more components to vibrate which will add additional noise, but not much, and there are ways to reduce that.)

In general, there’s a long-standing history of delineation between motorized and non-motorized areas and e-bikes are breaking the mold, creating the need for a better system to both classify and regulate the use of these vehicles. There’s a wider range of power within motorized vehicles these days, so classifying e-bikes with the 3-class model is a good first step to understanding where they should or should not be operated. As with all changes, implementing a better classification system across the board will go a long way to helping cyclists do what they love most: ride.

Something still unclear? Got other ebike motor questions we haven’t answered yet? Leave a comment and let us know.

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