Indoor Cycling is a great way to boost your cardio endurance. It is done on a stationary bike, which is designed to feel much more like a real bike than your average stationary bike found in a gym. The front wheel is weighted and has a resistance control that can simulate an outdoor riding experience of sprinting and climbing in a realistic fashion. An average indoor cycling class will last 45-60 minutes and vary from simulating a long ride to working on intense interval training. Whether you are looking to just get in shape and burn fat or work on skills that will improve your outdoor riding, indoor cycling is a great form of cardio exercise.