As on an ergometer or any other type of exercise bike, the same applies here: In addition to the resistance you choose, the duration of your workout is crucial. If you have just started exercising on your exercise bike, a few minutes of concentrated training are usually enough. The training impulses you set are already enough to improve your endurance. If you just want to burn as many calories as possible, you should of course train for as long as possible - preferably at high resistance. However, please never train too long in the maximum heart rate range. The answer to this question depends on your own training goals.