As you properly pointed out motors are generally built to their end output requirements. There may be motors that are built to a spectrum of output watts which means the motor is built to the largest output expected but used at a lower wattage. This derating would produce longer lived motors at lower wattage usage. I highly doubt that derated motors are being produced. Every ounce of metal be it copper, steel or some other costs money and this industry is about profits. That said speed should and is being used to regulate e-bikes here in California. They also mention wattage ratings with 750 watts being a more or less top motor rating for street legal use. I run a RAD City with a 750 watt hub motor which is regulated by its controller to 20mph. 20mph is way too fast for sidewalk operation in most situations but is fine for street use. I use the first level of PAS(power assist) at 54 watts which is the least amount of assist and manage 14mph all day on heavy duty 26"x2.25" MTB tires. I believe that being a very conservative user of the streets is always warranted. Big steel fenders always, always, always have the right of way no matter how mad you are at them. One can't keep up a high level of mad while resting in a coffin. I love my e-bike and ride it almost every day with my wife riding hers. She had stopped riding because of aging body components. These e-bikes have gotten us on the road for the last 3 years and it has been a very happy experience.
Last edited by tallbikeman; 01-02-24 at 07:15 PM.