Power: 2 ways rated in power. Volts from the battery and wattage from the motor. Certain voltage will be put in the battery, usually it is 24-72V .
Voltage have strong relationship with the acceleration of the bike. The higher the voltage the faster the acceleration. The motor output is measured in watts, this means the higher wattage the faster the top speed and acceleration. Normally the best electric mountain bikes range from 250W to 1000W.
But one important thing to be pay attention to is the higher the voltage and wattage the faster the bike will drain its battery. So if you go for a super-fast 72V 1000W combo, you will need a massive and expensive battery to get any decent range.
Most electric bikes we sell at zhsydz.com are 36 volt coupled to a 250 watt motor. This allows a comfortable acceleration and top speed of 25 km/h.
In some countries like USA electric bikes are allowed to a top speed of 32km/h,so most of our electric bikes sold to America will make 30-35 km/h in order to meet the needs of the US market. But in European countries, commonly customers just need max speed 25 km/h .So when you use an e-bike in different countries or areas,remember to choose the reasonable speed.And we always sell the best electric bikes to different countries/areas.