Torque is a technical term that may confuse a lot of electric bike riders. When buying an eBike, other than motor power, torque is an important parameter to pay attention to. A motor with high torque can significantly increase the fun of e-biking, especially when you are challenging steep hills.
What is electric bike torque?
Torque shows the turning force of the motor, that’s why electric bikes with high torque make it easier for riders to climb hills. For example, two people with two 250W electric bikes are riding uphill, the eBike with low torque will be very difficult to accelerate from a standing start, the eBike with a high-torque motor (more than 85Nm) pulls off with ease.
Torque is expressed in Newtons per meter (Nm). For most electric bikes, the motor torque is between 30 and 85Nm depending on the electric bike model. But there are still some 120Nm high-torque electric bikes in the market. Generally speaking, electric mountain bikes and off-road electric bikes use high-torque motors, because they are designed to ride uphills more frequently. Take two of the BuyBestGear’s hot-selling ebikes as examples, Ado D30C is a 250W city bike, the motor is 42Nm, and Shengmilo MX02S is a fat tire off-road ebike, its motor torque is much higher, which is 95Nm.
How is electric bike torque calculated?
The general equation for torque is Torque = Force x Distance, when a rider is pedaling, he or she creates a “Force” on the pedal and the “Distance” is the length of the crank arm, which is 17 or 17.5cm. If a person that weighs 60kg stands on pedals when the bicycle is on flat ground, then
Torque=60kg x 9.8N/kg x 0.17m=99.96Nm
When an electric bike is moving forward in pure electric mode, the “Force” equals the power that the motor exerts on the drive axle or the transmission (chain system, or hub gear with chain, belt ). That’s why a 95Nm torque electric bike can easily climb a 35-degree slope. When you ride in pedal assist mode, the motor supports you in addition to your own strength, so the electric bike will be more powerful and you can conquer much steeper slopes.
What does torque mean to an electric bike?
In one sentence, torque allows ebikes to accelerate and help cyclists to ride uphill. Electric bikes with higher torque get more force from the motor, so the cyclist will feel easier when pedaling uphill, and the electric bike will be faster to accelerate from a full stop to full speed.
Proper torque can prevent your electric bike from halting and stalling. When the electric bike itself is quite heavy(e.g. big wheel fat tire ebikes) or you are carrying a heavy load, getting the bike moving will be a challenge. If the ebike is equipped with a high-torque motor, you can do a lot less pedaling. Through the above example of a 60kg cyclist standing on pedals, you can see that the torque of 90+ Nm is very impressive. In fact, for most off-road e-biking, 40-50Nm motors can generate enough traction. Of course, the premise is that the load of the bicycle does not exceed its maximum load, otherwise the motor may be damaged.
How much torque do you need?
Normally, a 250W city commuting electric bike doesn’t need a high torque motor, you can buy a 25-40Nm one according to your preference. And 40-60Nm is the average torque for multi-purpose electric bikes, which can handle most mountains and slopes. But if you like to pursue excitement and want to challenge some steep hills, you will need at least 70Nm torque. For ebikers who live in areas where hills are everywhere, high-torque electric bikes are a must. Otherwise, you have to face the dilemma of sweating or rolling down like a marble on an inclined plane.
The torque and speed of an electric bike.
Electric bike torque measures the rotational force of the motor, it directly affects the acceleration of electric bicycles. When you are starting the electric bike from the complete stop, the motor torque increases to make the ebike reach a higher speed faster. When you already reached the top speed and start to ride at near-constant speed, the output torque of the motor will be the lowest. In another word, torque only plays an important role when you are climbing slopes or starting from a complete stop. When you are cycling at a quite high speed, torque is not important.
What is a torque sensor?
Another word that often appears with “torque” is torque sensor.
When cycling in pedal-assist mode, the electric bike uses a pedal sensor to “know” that you are pedaling. There are two kinds of pedal sensors, the cadence sensor and the torque sensor.
Compare to the cadence sensor, the torque sensor is more advanced (and more expensive). A torque sensor measures how hard the rider is pedaling to determine how much electric power to push to the bike. The harder you pedal, the more power it gives to the motor. If you pedal lighter, less power goes to the motor. It makes this adjustment in real-time, providing more natural-feeling cycling experience.
Here are some electric bikes that equipped with torque sensors