Exercise 1: sample answer

On a high wheeler the distance per pedal turn equals the front wheel's circumference. With a chain, the pedals turn a large chainring that drives a smaller sprocket on the rear wheel, so the rear wheel turns several times per pedal turn. A gear ratio of about 2.5 to 1 with a small wheel could give the same distance per pedal turn as a very large wheel (check the figures), so the rider could be as fast while sitting low, near the ground and between two small wheels.