Without a doubt, e-bikes are affordable, speedy, effort-saving, and comfortable, but you can only take these advantages by riding on the right electric bike.

To choose an electric bike that fits your needs, you’ve to look for certain specs, and among all the motor is a heading component that demands your prior consideration. So, here is a quick discussion about ‘what size e-bike motor do I need?’ for your better understanding.

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**What Size Electric Bike Motor Do I Need?**

As I said in the introduction, the motor is among the most significant parts of the e-bike and not all motors are the same. Therefore, you need to address and understand the differences to choose rightly.

There are different terminologies and units that generally express the voltage or power of the motor and define its capabilities. Companies or engineers use certain kinds of devices or meters to measure these values and share them with us in the e-bike product description section.

**Physical Dimensions Of E-Bike Motor**

The physical dimensions of the motor are not actually a matter of concern when we are talking about power and capacity. However, you can consider the size if you’re anxious about the body-to-weight ratio of your e-bike and other relatable features like stability.

In simple words, a bulky motor means a heavyweight electric bike, and a compact motor means a comparatively lighter e-bike. That’s all for physical dimensions, let’s move on to the power measurements of motor.

**Power Measurements Of Electric Bike Motor**

**1. Volt**

The strength of the motor and its power is measured in different terms or units like volts, amp hours, watt-hours, amps, watts, and newton meters. Volts is the unit of force or it is defined as the rate at which electric power flows through the current at a certain time period.

Let’s think of a faucet or valve; a volt is basically a determining measurement that tells the speed of the water stream that flows through the faucet.

**2. Ampere**

The motor measurement is also done in Amps or Amperes. An Ampere is a unit of electric current and it is defined as the quantity of electric power that flows through a current at a certain time period. The time is always measured in seconds.

Again, compared to the example of the faucet I explained above, the amps would be the water that flows through the tube in quantity.

**3. Amp Hours (Ah)**

The amp hours measure the energy capacity of the electric bike’s battery. Amps hours is shortly written as Ah and it measures the amount of current that can possibly be transferred to a certain point in no more than sixty minutes under a specific voltage. Also read about electric bike battery problems.

In the case of the faucet explanation, the Ah is the total quantity of water that comes out from the valve. I have also shared a detailed guide about eBike battery BMS reset.

**4. Watts**

Then comes the watts; a measurement of amps multiplied by the value of volts (A x V). Watts is a conventional unit of power that a motor can generate; likewise, the watts give an estimate of the motor capacity of an electric bike.

Considering the faucet example, the watts are equal to the force applied to the water stream for the flow.

**5. Watt Hours (Wh)**

Watt hours are somehow the same as Ah, but watt hours don’t measure the energy capacity but calculate the power that is delivered in total. In the case of the faucet, the watt hours are equal to the force that is generated by the water over a certain period of time i.e., an hour. It is shortly written as Wh.

**6. Newton Meters (Nm)**

Last but not the least, the Newton meter is another unit to measure the torque generated by the e-bike motor. For your information, torque is the force created by a turning object like a coil of a motor or any spinning thing. It refers to the force and in the pattern of the faucet, it is the force generated by the spinning of water.

**Recommended Sizes Of E-Bike Motor**

Now that you know about the measurements of e-bike motors, it would be easier for you to understand the standard recommendations. Let me explain!

For city electric bicycles, the 40 Nm or 250 W motor minimum is suggested, for e-bike cruisers, the motor size should be at least 50 Nm or 350 watts. However, mountain riding requires a bit of a powerful motor, so in suggestion, you should opt for at least a 60 Nm or 450 W motor for an electric mountain bike. Lastly, speed electric bikes should have a 65 Nm or 500 W motor.

**Frequently Asked Questions**

**Is a 500W motor enough for an eBike?**

To be honest, the 500 W motor is quite efficient and provides an ample amount of power to run the bike. According to standards, speed electric bikes are recommended to have at least a 500 W motor.

**Is a 250W motor enough for an electric bike?**

The 250 W is the most common motor size in e-bikes and it provides a speed of up to 25 miles per hour, which is pretty considerable. Mostly, cruiser electric bikes have this motor size and they are suitable for casual commutation.

**Is e-bike motor size measured in Nm?**

Yes, the Newton meters (Nm) is a unit to write the motor size. Basically, Nm is the torque generated by the e-bike motor. For your information, torque is the force created by a turning object like a coil of a motor or any spinning thing.

**Final Thoughts**

**Final Thoughts**

In a nutshell, the size of the motor for an e-bike greatly depends on the final application. For instance, if you need a cruiser e-bike, the motor size suggestion would be different than that for mountain riders. In this article, I have explained the measuring units and their definitions in detail for your clear understanding and along with that, I have added some standards to answer what size e-bike motor I need. So don’t forget to go through the article!

Hi, I’m Robert A. Cannon, Electrical Engineer by profession and travel enthusiast! I has been passionate about building electric circuits and remodeling since my childhood. Following my passion, I graduated as an Electrical Engineer from University of Houston and turned my passion into a profession. I have worked in different electric vehicle manufacturing companies.

Following my professional expertise and experience in using different electric vehicles, I started EGearLab to assist the community in finding the right e-gear for transportation according to their needs. Feel free to contact me at anytime for queries related to electric outdoor vehicles!