The biggest advantage of spinning is to lose weight wherever you want! If you want to have slim arms, you can bend your arms 90 degrees, hold the handlebars tightly, and tighten your arm muscles to make the muscle fibers slimmer. If you want to shape the calf, you can imitate the action of going up the mountain. The thigh drives the calf to be passively stressed, which can consume more calf fat without growing large muscles.