The rear wheel of a bicycle has a set of sprockets whcih vary in size. The chain hooks onto the sprockets, and when a pulling force is apply to the chain, the sprocket, hence the wheel turns. As any cyclist knows, when going up a hill, to maintain a constant velocity, it is better to use a lower gear, or larger sprocket. Why? In your answer, consider what the net torque is at constant velocity. Ok so obviously, the larger the sprocket the easier it is to pedal, but I'm not quite sure why...I dont even know if that will apply here or not.