A bike frame is the main structure of a bicycle, providing support and shape. It is typically made from materials like aluminum, steel, or carbon fiber, each offering different benefits in terms of weight, strength, and cost. The frame connects various components, including the wheels, handlebars, and seat, making it essential for the bike's overall performance and stability. Frames come in various styles, such as road, mountain, and hybrid, designed for specific riding conditions. The geometry of a frame affects how a bike handles and feels while riding. Choosing the right frame size is crucial for comfort and efficiency, ensuring that the rider can maintain proper posture and control.