Originally Posted by
Polaris OBark
There is.
For class 1, assist must cut off at 20mph. The high-quality systems like Bosch make a big selling point of how they ramp down the assist as they approach 20 mph so that the transition is smooth. In other words, if you are pedaling at 21 mph, you are doing so without any assist on a class 1 ebike. I tried this on my wife's bike. The transition is smooth, but I can feel it.
For class 3, the cutoff is 28mph. I assume it works the same way with the throttle and class 2.
Again, not all states adopted the various classes, and there is no guarantee that the states that did defined them exactly the same. I don't believe there is a federal regulation limiting speed. Some European countries do. Bosch units designed for the European market carry some of that over, like their 250 watt limit.