The speedo sender, also known as the speedometer sender or speed sensor, is a component that measures the rotational speed of the motorcycle's wheels or transmission. It converts this rotational speed into an electrical signal, which is then transmitted to the motorcycle's speedometer or digital display. This allows the rider to see the current speed of the motorcycle in real-time. The speedo sender is crucial for accurate speed readings and helps ensure proper functioning of the motorcycle's speedometer and other related systems.