There are two types of exercise bikes, which are the upright and the recumbent type. While both are primarily intended for training, they are not the same when it comes to intensity.
For beginners, the most suitable choice is the recumbent type, which offers less intense workouts. For more advanced training, it is more advisable to have the upright type.
The recumbent bicycle is a lot larger than the upright one, and you cannot stand up while biking, unlike with the latter, which means less intense workouts.
Also, although there is no standard recumbent bicycle, all of them are designed having larger seats than the upright type, so they are much more convenient to use, which is ideal for older people and those who are obese.
The upright bicycle, however, is ideal for advanced users because it offers more features, such as a screen monitor where the heart rate of the person is displayed, along with the distance travelled and the calories burned.