The Basics About Electric Bike Motors
by GanterRosie on Mar 06, 2023
Electric bikes are gaining more popularity as two-wheeled electric transportation for recreational riding and commuting. Mid-drive motors and hub motors are the two most common e-bike designs used in today's electric bicycles. Both have their own set of pros and cons, so deciding which motor is best for you will primarily depend on your demands and which advantages appear to be more helpful. In this article, we will be talking about the basics of e-bike motor types. Read to know more!
How Ebike Motor Works
To begin with, an electric motor is an energy converter that turns electrical to mechanical or electromechanical energy. It transforms electrical energy into mechanical motion (translational or rotational). Motors are propelled by torque, a force that spins objects around. When power is applied to the motor, torque is generated, which causes a drive shaft to spin. The shaft then drives a chainring. The chain drive provides the forward force, which works in tandem with your pedaling effort. When power leaves your battery and travels to your ebike's motor, it makes a brief halt at the controller. The controller controls how much power is provided to the motor in any electrical device, essentially deciding how fast it spins.
The speed limiter allows you to pick less than full power when you want optimal efficiency. Then there's the electronic braking system. The e-brakes do not electronically stop you; instead, they detect when you pull the brake levers and signal the controller to stop the motor if the throttle is stuck. When you let go of the throttle, it usually springs back, but if it doesn't, the e-brakes will stop the motor from pushing. The familiar cable that initiates standard bike brakes is also present on the e-brake handle.
Things can get a little more complicated with an electric bike, depending on the extent of help provided by the bike model. If you wish to ride without assistance, you can use "pedal only mode," in which the engine receives no power and all of the efforts are done by your legs the old-fashioned way. Then assume you see a big hill ahead of you, and you don't want to get too sweaty. You may now activate "pedal-assist mode," where the motor and you work together. The ratio of human to machine power varies depending on how hard you work and how hard you pull on the throttle, but in any case, both your legs and the motor are working together to spin your bike's back wheel.
Different Types of Ebike Motors Explained
Although a few other electric bike motors are the most popular, hub motors and mid-drive motors, we'll focus on those two here. Hub motors are fitted directly inside the bike's front or rear wheel hub and are more popular than mid-drive motors. The motor system on a hub motor electric bike is entirely independent of the bike's powertrain. On the other hand, a mid-drive electric bike incorporates the bike's drivetrain. When combined with a derailleur-type drivetrain, it employs the gears and chain for power.
Mid-drive motors are found between the cranks of an e-bike. Torque is generated by an electric motor, which spins a shaft attached to a chainring. Rather than providing an additional power source, the motor supplements your pedaling power within the bike's chain drive. The motor pack also has a gear-reduction mechanism. According to Bosch's Weinert, while mid-drive electric bike motors spin hundreds of times per minute-much faster than you can pedal-the motor's inner gear decreases the RPMs at the shaft, allowing the system to run at a rider-friendly cadence of 50 to 80 RPM. All mid-drive systems except the cheapest have gear sensors that limit the power to the motor while you're changing gears to prevent the chain from breaking while the bike isn't in gear.
Mid-drive motors have grown much more widespread in recent years, threatening the hub motor's dominance as the king of the e-bike motors. It puts the motor near the middle of the bike and transfers the engine's power to the rear wheel through the bicycle's chain drive. Mid-drive motors are directly connected to the crankshaft, where the pedals, drivetrain, and chain are located. Currently, this is the least popular method of powering electric bicycles, although it is gaining popularity. However, they are more expensive than other types because of their availability.
Pros and Cons of Hub Motor
Front hub motor pros
- Most old bikes may be retrofitted with new front hub motors, which are very light and straightforward to install.
- Front hub motors work well with hub gears, derailleurs, and belt-driven motorcycles.
- Hub motors are less expensive than mid-drive motors since they can be mounted on a standard bicycle frame.
- Motors for the front hub are simple to replace or repair (dependent on type and seller).
- You don't have to change the gears at all if you retrofit with a front hub, and it's a relatively simple conversion (so reasonable costs tend to be cheaper). It's also simple to reverse the conversion if you want to switch bikes.
- The drive chain on the front hub motors does not require much maintenance.
- Hub motors love to spin, so they're perfect for combining with gears. When using a hub motor, you don't have to push if you don't want to, hence, these motors provide more assistance than mid-drive motors.
Front hub motor cons
- On dirt roads, front hubs lack grip, causing the wheel to spin upon start-up, especially when traveling uphill.
- Some lighter-weight hub motors offer less torque at low speeds and should not be utilized for hauling, riding on mud, or a lot of uphill riding.
- Some old front motors are heavy, affecting the bike's weighting.
- Changing a tire isn't as straightforward. It will require the use of a spanner.
- Front brake pads are showing a little more wear.
- They require more battery power.
Rear hub motor pros
- There is a broad range of power options because the support built into bike frames can manage it.
- The control pedal assist sensors are more intuitive and responsive than their front hub counterparts.
- Almost all motorcycles are propelled by running power to the rear wheels. As a result, they are pretty similar to riding a standard bike and have a very low learning curve.
- Excellent, with a throttle function to assist you in getting off the line quickly.
Rear hub motor cons
- Rear hub motors are more difficult to change tires than the front or mid-drive motors.
- Rear hub motors have a higher rate of spoke breakage than front hub motors, especially if the bike is loaded heavily on the back.
- They require more battery power since they are less efficient than mid-drive motorcycles.
- Retrofitting hub gear bikes with rear motors is not possible.
- The rear brake pads are showing a little more wear.
Pros and Cons of Mid-Drive Motor
Mid-drive motor pros
- A mid-drive motor is often situated in the bike's center, between the pedals, to ensure even weight distribution. This center arrangement results in more even weight distribution, improved handling, a smooth ride, and simplicity of carrying.
- Sensor systems: Since mid-drive motors are pretty modern bike motors, they frequently include novel sensor systems, especially pedal assist and gear shifting. Some of these systems may foresee when the rider is about to shift gears and adjust the motor's power output properly, leading to a smoother transition.
- The torque created by the powertrain is harnessed by the mid-drive motor, resulting in rapid acceleration and improved power for steep climbs.
Mid-drive motor cons
- To maximize the effectiveness of the motor, it must be shifted appropriately, which means you must always be in the appropriate gear for the terrain.
- Increased wear and tear on your ebike's drivetrain
- There are no forward gears, restricting the number of ratios available to only those on your back wheel.
- The chain can snap if you shift gear while under significant motor power.
- Since the motor is embedded in the bike frame, replacing it is costly.
- If you don't change down before stopping, you won't be able to change gear until you restart.
How to Choose the Ebike Motors
One of the most crucial decisions you must make when purchasing an e-bike is choosing between a mid-drive or hub-drive motor. The motor system you choose can significantly impact the quality of your ride, so it's essential to understand the differences. A hub drive motor built into the front or rear wheel is the most common motor seen on less expensive e-bikes. Although the latter is more popular, some e-bikes feature motors on both wheels. A hub drive provides torque to the wheel directly, bypassing the gears on your bike. Electric bikes with mid-drive motors are frequently the most responsive, particularly when it comes to pedal assistance. On average, they provide more peak assistance/output than hub-drive, making them an excellent choice for off-roaders and electric mountain cyclists.
If you're wondering which is better, the answer depends on your needs. If you merely use your bike to commute to work and cruise through parks and around town, a hub motor is a way to go. However, a mid-drive motor is your best bet if the mountains call you and that slope in front of you looks like the perfect location to put your talents to the test. Whatever option you choose, the most important thing is to have a good time and enjoy your journey.