Force in Bicycles

The two forces applied to bikes are external and internal forces.

• Internal forces are applied by the rider of the bicycle or the friction.  The rider applies the force through steering the bike.  It happens in the handlebars, wheel, and pedals.  It is generally a torque that is applied.  The friction is caused in many different areas: from the ground, the gears, the brakes, and the pedals.
• External forces are applied from gravity.  The pull of gravity causes the external force of the bike. There is the riding resistance the ground creates, the air-resistance and drag the air creates, and force from braking.