It may sound silly but it works!
I have started an rc car in the early 80's with a bicycle wheel, turn the bike upside down, have somebody hand pedal to spin the rear wheel, while the wheel is spinning you can then bump the flywheel against the tire! just make sure it is spinning in the forward position, the best will be an on-road bike so the tire will be narrow enough to pass through the chassis and hit the flywheel.