A hub motor has a low speed uphill and thus a very poor efficiency. When driving uphill, the speed is low but the required power is high. Why using a mid-drive motor?įor a high efficiency, a permanent magnetic motor must have a high speed, see this article. The official motor power is the power that can be delivered continuously without overheating or otherwise being overloaded. A 250W motor can easily deliver a much more power, for example 500W, and that occurs in practice, when accelerating and going uphill. Note that the power of a permanent magnetic motor is a relative term. This graph with motor curves circulates on the internet, but it is not correct, compare the yamaha with my graph above: It is very important to know that it is almost impossible to develop a motor with a much higher efficiency. This is due to the laws of physics, there is no better conductive material than copper and there are hardly any better permanent magnets than Neodymium. I have measured the motor parameters and made the motor graph, see the article about the Yamaha PW-SE.
This mid-drive motor has one of the largest gear ratios, and therefore the highest efficiency.
Here is the motor power graph of the Yamaha PW-SE. In practice, the maximum motor power will be limited by the motor controller and the software, but in this article, we focus on mechanical properties. From a mechanical viewpoint, the only substantial difference in performance is determined by the gear ratio. By nature, all small permanent magnetic motors have equal characteristics. That is because all use the same motor type: a permanent magnetic motor. It is important to know that, from a mechanical viewpoint, all well-built mid-drive motors of 250W are more or less the same. Mid-drive motors compared from a mechanical viewpointĪll 250W mid-drive motors have about the same characteristics
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The differences in driving experience, and the many tests you find in magazines, are mainly caused by the pedal-assist software and not by the motor itself. Most motors use pedal assist control and this is in particular very software dependent. With another software or motor controller, mid-drive motors may behave completely different. Why compare mid-drive motors on mechanics?Įbike mid-drive motors are often compared with each other, but this relates always to behavior and performance and these properties are mainly determined by software.
The Yamaha PW-X2 is also used by Giant and is called the SyncDrive Pro. Who can help complete the missing data in the list? In this article, mid-drive motors of 250W and maximal 3.5kg are compared from a mechanical viewpoint. Which e-bike mid-drive motor is the best?
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