I'd say the gears on a bike acts as levers, as pedals and driven wheel turns with different speeds and force.
Wheel and axle.
A sprocket is a lever.
To do bicycling you need a bicycle. And the bicycle is a man-made item relying heavily on techology to provide all the bits and pieces.
Gears on a bike are a type of wheel and axle simple machine. As the pedals turn the circular motion into rotational motion, the gears on the bike increase or decrease the force needed to propel the bike forward.
Eliptical Machine
Handlebars are considered a lever simple machine because they help to amplify the force applied by the rider to steer the bicycle.
A pulley isn't a kind of simple machine, it is a simple machine
The type of simple machine that a slope is, is a inclined plane
it is a valve, which is not a simple machine.
A person uses mechanical energy to pedal a bicycle. As the person pushes down on the pedals, this mechanical energy is transferred into rotational motion to turn the wheels of the bicycle.
a simple machine.