Question

a) Where on a bicycle do you want to reduce friction to a minimum? How is it done?

b) Where on a bicycle do you want friction?

Answer 1

a) You want to reduce friction in the gearing between the pedals and the wheels so that nearly all of your mechanical energy is transferred to the rotation of the wheels. This is done by oiling the chain and gears.

b) You want friction between the tires and the road so that energy is not lost due to slippage between the tires and the road.