Motor Overview

The electric motor is the heart of your electric bike, ebike kit or scooter.  Its manufactured specifications determines top speed, acceleration, hill climbing ability, power consumption, performance and ultimately distance.  Not all motors are built the same in terms of quality and durability.  When picking the right motor for you its important to understand a little more in depth of what to look for.

Power….Efficiency…Durability

Just about all electric bikes and ebike conversion kits have a motor power rating in units of watts.  A watt is a measure of power equivalent to joules per second or energy per second.  In laymen terms, it the amount of power or energy a motor can handle or “consume” continuously.

A motor with high wattage will consume a lot more energy in a shorter amount of time compared to a smaller wattage motor.  With greater energy consumption, the more mechanical power a motor in theory should produce.  In general, a higher motor watt rating means the motor should accelerate more quicker (greater torque), carry more rider weight, and assist on steeper hills.

With all of that said, not all motors are created equal even when comparing two motors of equal wattage.  If you take anything away from this article, it should be that, watt rating doesn’t always tell the whole story. In fact, a wattage rating may be the least indicative measurement when choosing an ebike.  It’ as equality important to note the controller and battery have a lot more to do with how an electric bike performs. Some manufactures offer 500-750 watt motors, but this doesn’t mean they are superior.  The goal is to find the lowest wattage motor with the highest quality mechanical components and efficiency.  Lower quality motors may use higher wattage to match the efficient of lower wattage motors to produce the same mechanical power. This is because motor power doesn’t capture how efficient the motor is.

Lower quality motors may use higher wattage to match the efficient of lower wattage motors to produce the same mechanical power.

to find the motor power (watts, W), consider a motor running at 36 V and 7 A; it has a power output of 36 V x 7 A = 252 W.

Motor Torque

Torque is the measure of the twisting force produced by the motor.  It is commonly given in units of Newton-meters (Nm, or pound-foot for countries using imperial). Torque is the main force that rotates your ebike’s wheel and is responsible for propelling you forward.

A lot of manufacturers hid or inflate torque output specifications for their motors, but this is an important part of your ebike’s motor specifications.  You can estimate it using the relationship that power is equal to torque multiplied by revolutions per second (RPS) or Power (W) = Torque (Nm) x RPS.

By dividing the motor power by max revolutions per second, you can estimate torque. Sometimes called stall torque, DC motors produce their maximum torque at zero revolutions per second. Peak power output is found at half the max revolutions per second and half the max torque.

Torque specifications are an important part your e-bikes performance!

Motor Performance

Manufactures motor power is a generalized way to compare the performance of ebike motors. The ebike with the more powerful motor should hypothetically, accelerate faster and carry heavier users.  However, as mentioned, this “power rating” doesn’t always tell you the whole story.  Additionally, many manufacturers over exaggerate or  measure motor wattage differently or show max wattage only.  As such, we always recommend you consider specifications looselyand base your decision on companies who provide all the specs.

Always use wattage to loosely when comparing motor performance, it should not be the ultimate decider of an ebike’s performance.

When reading motor specs and power ratings, you must note there is a difference between peak power vs. sustained power.  Peak power refers to the maximum power the motor can consume for short periods of time. It is generally not a very useful tool for comparing electric bike kits.  It seems many manufactures also over estimate this number and many manufacturers quote the peak power of their electric scooter as a way to deceive users.

Sustained or continuous power is the maximum amount of power the motor can consume indefinitely. This is the most useful measure for comparing motor performance among electric bike motors.