When using an exercise bike it is extremely important to be able to monitor your heart rate while exercising! Always buy an exercise bike with a built-in heart rate monitor so that you can adjust your workouts accordingly. Almost all the exercise bikes do have this although cheaper ones will often just have a pulse rate monitor built into the handlebars. The more expensive exercise bikes will have workouts that are driven by your pulse rate so they adjust themselves to keep your heart rate at level that you set. This is a very nice feature but not essential if you can’t afford it.