Controller Is The Brain Of The E-bike
E-bikes have a "controller"-- some kind of computer tha […]
E-bikes have a "controller"-- some kind of computer that manages all the signals coming from the various sensors and switches, and distributes electrical power throughout the system accordingly. Sometimes, that means powering up the motor, sometimes that means turning of the headlight. It is the "brain" of the bike.
The other meaning for "control unit" would be the display on the handlebars that allows the rider to make various adjustments to the bike's settings (power on/off, level of assist, etc) as well as read outs for things like battery level and wattage consumption -- speed and distance too in many cases. Increasingly, some manufacturers are using the rider's cell phone and an app for this functionality. One thing to consider: if your cell phone runs out of battery, you won't be able to use the electric aspect of your bike.
Most electric bikes have a lock in the controls to stop provide electric assist at 30kph or 20mph. There are ways to remove the lock so the electric motor plus you pedals can go as fast as you have the power.
Though this solely depends on the regulations guiding the use of e-bikes in a particular country. There are different rules governing the speed limits of electric bikes in different countries which riders must strictly adhere to.