Exercise machines resembling modern stationary bicycles have existed since the end of the eighteenth century; the Gymnasticon was a prominent early example of this.
Most exercise bikes provide a mechanism for applying resistance to the pedals which increases the intensity of the exercise. Resistance mechanisms include magnets, fans, and friction mechanisms.
In recent years, many new stationary bikes have appeared, including those in recumbent positions, upright bikes and indoor cycling bikes which are bikes built for riding in indoor cycling classes. Some models feature handlebars that are connected to the pedals so that the upper body can be exercised along with the lower body.