in more energy transferred into motion. Voltage pushes amps to cause the motor to turn and do work. 

WHAT’S A WATT?

The amount of work the electricity does is measured by watts. However, some energy is lost through heat. Poorly made motors can consume a lot of energy and not do much work. As such, just because a motor has a high wattage does not necessarily mean it will perform well. The motor could just sit there and get hot. Further, you may not need a lot of wattage to propel your ride. Typical wattage ratings are 250 watts to 750 watts. (Over 750 watts is not considered a bicycle in most jurisdictions; it’s a moped or motorcycle.) Some of the newest e-bikes are coming out with lower, not higher, wattage. Now, you might find a very lightweight bike with a smaller battery and motor that performs nearly as well as a similar older and heavier bike. 

WHAT ABOUT TORQUE?

This is twisting force. A motor’s torque is a good measurement to compare its ability to twist the wheels of the bike. Many bikes now list their torque spec. Typical levels are 50 N/m to 120 N/m (that’s 37–89 foot-pounds). Unfortunately, like many specs, there is no universal standard measurement. Torque is leverage, and that leverage ratio can be changed through gearing. That’s why center-drive motors have lower wattage ratings; shifting changes the way the torque is applied. Torque also changes as the rpm change. As a result, it’s hard to compare one motor’s performance to another using only torque as a guide. More is not necessarily better. After about 120 N/m of torque, the motor puts tremendous stress on the drivetrain. Go above 120 N/m and you really have a motorcycle. As with anything, it’s best to take a ride and then decide.

WHAT ABOUT WATT/AMP-HOUR?

As the name suggests, it’s the amount of energy in a battery as delivered over time. For example, a 10-Ah battery will deliver about 1 amp of current for 10 hours. Similarly, a 500-Wh battery will deliver…

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