Yes. Both the Explorer and Summit system can be ridden as a normal bike with out using the motors. You can ride them even with the battery removed.
Both motors have a freewheeling system meaning you are not turning the motor when it is not in use, the bike rides as normal.
Both systems have a throttle so you can ride the bike like a normal bike then press the throttle when you need a boost to climb a hill or pass a young man wearing licra.