A spin bike is a stationary exercise bicycle designed for indoor cycling workouts. It typically features a heavy flywheel, pedals with toe cages or clip-in mechanisms, and adjustable resistance levels. The design allows users to simulate the experience of outdoor cycling, engaging in high-intensity cardio workouts. Spin bikes often come with adjustable seats and handlebars to accommodate various body types and riding positions. Some models may include additional features like a digital display for tracking speed, distance, and calories burned. Spin bikes are popular for their effectiveness in cardiovascular fitness and lower body strength training.