How fast an ebike can go depends on the size of its motor. Almost every ebike you’ll see in the USA is capable of exceeding the speeds it is limited to. It is common to see ebikes categorized regarding their speed and functionalities using a tier system of three classes:
Class 1 - 20mph with only pedal-assist
Class 2 - 20mph with pedal-assist and a powerful throttle function that negates the need to pedal
Class 3 - 28 mph with only pedal-assist
These classes are not yet set in stone, more on that in the next section, but they’re the guidelines that most ebike companies follow when designing their ebikes because these classes are turning out to be the preferred framework for legislators.
Whether or not an ebike in each of these classes can reach its permitted electric bike top speed depends on the payload it is carrying and its motor output. The maximum speed of an ebike will be relative to both its payload and the power output of its motor, but, in most cases, with just you on your ebike, you’ll be able to reach the class limits placed upon it.
It is worth noting that higher speeds can be reached by pedal power and the assistance of gravity because the speed of the bike itself is not limited, rather the electric assistance cuts out when the class limit is reached.