When one ventures into the world of e-bikes, they venture into a world of terminology that is foreign to most. Watts, torque, amps, volts, amp hours, watt hours, etc. For someone who knows that their house runs on 240 volts and car runs on 12 volts and not much more, it can be daunting.
Today we try to break this down and we’ll promise to keep the jargon as minimal as possible.
Understanding power - WATTS
The wattage of your e-bike are both the most and least important elements of your bike. They are the most important as the laws govern the maximum watts an e-bike can have to be legally ridden on the roads in Australia.
The maximum power allowed on an e-bike in Australia is 250 watts.
This is extremely important. You will see e-bikes available with 500, 750 or even 1,000 watt motors. These can’t be legally ridden on the roads in Australia. Get yourself tangled up with a car and good luck with CTP insurance covering you, and expect to end up in court defending yourself.
Why 250 watt?
This is a bit of a sore point in the industry. 250 watts of power was an arbitrary number that the Europeans came up with to regulate e-bikes. They came up with that number in the 90’s when Yamaha released their first e-bike motor… the motor had 250 watts of power.
Why watts are a poor measure of power
Remember when you used to by 60, 80, 100 watt light globes? Then LED light globes came out and all of a sudden they were 8 watts? Technological changes meant LED light globes were much more efficient than the old style globes.
Watts are simply the measure of how much electrical charge is flowing, not the performance of the end product.
This is why light globes moved to lumens as their standard for measuring how powerful a light is, after all it is the amount of light that you get from a globe that you measure it by. It’s for this very reason that torque is the superior form of measurement for e-bikes.
Understanding Torque
Simply speaking torque is a measure of force around a point. When you push a lever you are using torque to push this.
Lets say, you are trying to open a door. If the handle was close to the hinge, the door would be very hard to open, however as the handle is at the furthest point from the door it is easy to open. By applying the same amount of work, the door is much easier to open from near the side, due to the power of leverage increasing the torque or the force around the point (in this case the hinge).
Torque is super important with e-bikes as like a lumen is the most accurate way to measure a light’s brightness, torque is the most accurate way to measure the power around the wheel or the crank. More torque = easier to pedal.
Newton Meters (nM) are the units used to measure torque, with the higher the Newton Meter the more assist your bike will give you.
Amps and Volts
Amps and Volts add another element to the power discussion. Volts can be considered like the lanes on a freeway, with more volts being a wider lane freeway, with Amps being the amount of electrical energy.
Amps, Volts and Watts are inter-related, with amps multiplied by volts equalling watts.
You’ll see e-bikes often marketed as 36v or 48v. Given the key constraint that they must work with are watts (remember the 250w power limit in Australia), a 48v battery must have lower Amp output than a 36v battery.
On their own they’re therefore not telling a huge story. We think it’s best to let the engineers work out the right balance between amps and volts, and not be hoodwinked into believing 48v is more powerful than 36v. After all, it’s the Torque we’re most concerned about!
The power and torque of a Tribe Bike
We believe it is super important for all of our bikes to comply with the Australian laws. As a result all of our bikes have 250w motors.
On our Tribe Original, we offer 2 motor options, a rear hub motor with 35nM of torque and a mid drive motor with 80nM of torque. Why the big difference in torque between the two? Essentially the mid drive motor could be considered the LED of the light globe world. It is more efficient at converting power into torque. This greater power comes at a higher financial cost.
From a hill climbing perspective, the mid drive motor (a Bafang m400) is recommended if you need to get up hills. The power is exceptional, even with a heavy load.
