An electric bicycle, also known as an e-bike, is a bicycle with an integrated electric motor which can be used for propulsion. E-bikes use rechargeable batteries to power a motor which can be either positioned in the wheel hub (hub motor) or a mid-drive (mid motor), positioned by the pedal crank.
The world’s population of e-bikes is expanding rapidly due to recent developments in electric motor and battery technology. It is estimated there are now around 250 million e-bikes in operation around the world.
In New Zealand an electric bike may be ridden on the road without a licence or registration as long as the power output does not exceed 300W. All the road rules associated with normal bicycles apply to e-bikes. As such, all e-Bikes must comply with the ASNZ Standards for safety. (Note that very few e-Bikes sold in the NZ market have ASNZS safety approvals).
As has happened with battery operated power tools, there is a trend towards higher voltage motor systems for e-bikes. Most early e-bikes had 12V or 24V systems whereas the latest e-Bikes tend to use 48V systems. This means a lower current is required for the same power, which increases both efficiency and peak power.
Which Motor Type is Best – Hub or Mid?
Many people ask this question – the answer is … it depends. If you need a bike that you are going to throw around a bit while riding more demanding trails then you should be looking at a mid motor bike. A mid motor bike will give you better balance as the weight of the motor is low and in the middle of the bike. If you are just going to ride on roads and light tracks then a hub motor could suit as the cost is generally significantly lower for a hub motor.
Note that most hub motor e-bikes in NZ do not have torque sensing and instead have a (much cheaper) sensing system to detect movement of the pedals. This type of sensor is called a speed, or cadence sensor. The issue with speed sensors is that they are slow to react – taking about half a revolution of the pedal before they kick-in, and they are also slow to switch the motor off, which can be a safety issue. They also cannot control how much power is being applied from the motor and simply apply full power every time the sensor is activated.
All Bionic e-bikes have torque sensing controlling the motor operation. A light press on the pedal initiates a light level of motor power, while a heavy press initiates much higher power levels. The result is a much smoother, more natural feel when you a cycling. Torque sensing systems are also more economical on battery consumption, generally delivering between 5-10% better range than speed sensor systems.