<human>:  How does a bicycle work?
<bot>: A bicycle works by harnessing the energy from a rider's legs to rotate cranks and pedals, which power the chain drive that turns the rear wheel and ultimately propels the bike forward. The gears on the bike help the rider adjust the amount of force, speed, and resistance to suit their preferences and the terrain they are biking on. Additionally, the two wheels and the frame work together to provide balance and stability while riding, allowing the rider to stay upright on their bike as they move forward.