Originally Posted by
Leisesturm
As I understand it, even in the U.S., motor wattage is not an absolute. The way I have heard it described (simplified) there is no actual difference between a high quality 250W, 500W or 1000W motor! A CHEAP 250W motor will burn up and be destroyed if 500W of power are put through it for even 5 seconds. A more robust 'better' motor can withstand more heat and will get a higher wattage rating but it is not more powerful, just better made. The BATTERY determines the rating of the motor. Voltage x current = power rating. The motor has nothing to do with it. The motors are made in China and the ones that go to the EU (and UK) are only allowed to have 250W put to them. In the US they are allowed to have more, whether they are up to it or not. The highways and byways of the U.S. are littered with the blackened, half melted, pot metal casings of sub-par e-motors bogged to death by lazy operators. You want to see that happening everywhere?
ALL mid-drive systems except the Bafang and Tongshen DIY systems use proprietary mounting shells that must be factory installed when the frame is being built. It's not a conspiracy. Well, no more of a conspiracy than MTB components having different dimensions than ROAD components. If you are not behaving like an absolute hooligan on your e-bike you will never be stopped by law enforcement to inspect your motor. In 2023 no manufacturer has yet come up with a way to limit the un-assisted speed of a bicycle. But up to the assist limit all bets are off. The 250W system is more powerful than any three moderately fit cyclists you could find. Who needs more?
The EU certification is written that at 250W the motor will maintain its temperature but at 251W in essense it would start to overheat so many have said that there is no maximum rating but of course in the real world such a motor could only be used lets say 10% over that rating without too much heat damage etc but in reality motors are being used to 900W and hugely different motors are being certified with completely different thermal properties as 250W. Also hub motors are much more effectively cooled as there is more motor mass, they are surround by a spinning fan (the wheel), they have less or no internal gearing or belts and the heat generating controller is external so under those rules hub motors should be allowed far higher wattage. As far as I understand it the US regulations are far more honest and engineering focused. Yes a 750W rated motor might peak at over a 1000W etc but the continuous rating is pretty accurate even if sellers like to call a 750W motor a 1000W motor due to its peak values. I don't think the motor mountings are a conspiracy although a standard mid-drive motor mounting is possible that all companies would use would be my preference. The possible conspiracy is the fact that some ebikes are given a 250W rating where as other less powerful ebikes are not, the certification seems manipulative and confusing in order to promote short life and expensive European products. However its also possible the certification is just written by someone incredibly incompetent or naïve and took too much information from European manufacturers which skewed the certification. The certification is also heavily against throttles which is the most common power control method in the world, it's electronically simple and gives the rider full control of power and when to use it. It helps the elderly, weak and disabled use ebikes more easily. It should not be legislated against. In the UK we have had to setup a 250W LPM sub class of moped which operates the same as ebikes (no helmet, insurance etc) in order to help such people get access to ebikes. It's messy legislation which not everyone understands in order to work around the EU legislation but as far as I can tell those ebikes need to be actually 250W as all of them seem to use fairly low power hub motors, I've not seen any with 900W mid-drive motors that call themselves 250W.