Bike size refers to the frame size of a bicycle, which is crucial for comfort and performance. It is typically measured in inches or centimeters and corresponds to the length of the seat tube. Choosing the right bike size ensures that the rider can reach the handlebars and pedals comfortably, promoting better control and reducing the risk of injury. To determine the appropriate bike size, riders can use their height and inseam measurements. Most bike manufacturers provide size charts that match these measurements to specific frame sizes. Additionally, test riding different sizes can help find the best fit for individual preferences and riding styles.