What is an e-Bike?
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 many of the latest e-Bikes use 48V systems. Using a higher voltage has several advantages:
- efficiency is improved as heat losses are lower
- electronic components are less stressed with lower currents
- motor peak power is higher
Which Motor Type is Best – Hub or Mid?
This is probably the single most commonly asked question asked about e-bikes, and the least understood. The answer is … it depends. At Bionic Bikes we have a selection of both mid motors and hub drive motors so we are not biased one way or the other. We just want you to have the right bike for you.
The Facts: 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 an e-bike with a mid motor. A mid motor will give you better balance control as the weight of the motor is low and in the middle of the bike. If however you are just going to ride on roads and light trails then a hub motor could suit as there is no noticeable difference in the weight distribution for this type of riding. Also, the cost is generally substantially lower for a hub motor.
Note that most hub motor e-bikes in NZ do not have torque sensing and instead have a very basic 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 half to a full revolution of the pedal before the motor kicks in. They are also slow to switch the motor off, which can also be a safety issue. They also cannot control how much power is being applied from the motor and simply apply full power (depending on the level of PAS selected) every time the sensor is activated.
All Bionic hub drive e-bikes have SensorDrive technology 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. SensorDrive is also more economical on battery consumption, generally delivering between 5-10% better range than speed sensor systems.
Mid motors generally produce more torque than hub drive motors, however you need to be in the right gear in order to use this torque (as the transmission is after the motor – like a manual car). If, for example, you try to climb a hill in too high a gear with a mid drive, the motor will be turning too slowly to develop high levels of torque. Hence it is important with a mid drive that it be ridden in the correct gear. With a hub motor the motor is after the transmission, so it doesn’t matter what gear you are in, you can still achieve full power from the motor. Therefore, if you are not competent with your gear changes you may be better to consider a hub drive e-bike.