Well it depends on the bike. On this bike model and many others, no you don't have to pedal, you can just push the button and go. It's actually easier to pedal just a bit to kick in the boost than it is to have to hold the thumb button down imho.. There's also different gears available like a regular 10 speed so you can choose how much resistance you want for the pedaling. It's very nice to have the different options.