Exercise bikes are easy to use and provide an effective workout.
They are easily adaptable to a home gym setting because they can be reasonable in price and usually do not require a lot of space.
Exercise bikes are very low-impact. There is no jarring of the knees or feet as might occur with a running or other aerobic exercise plan. Further, the pedal tension can be adjusted. Higher tension will increase muscle mass while lower tension will help with endurance.
It is easy to entertain yourself while you are on an exercise bike. You can either position the bike in front of a TV or prop a book on the handlebars and get some reading in.
Exercise bikes are also a good way to get exercise in even if the weather doesn't allow you to exercise outdoors --- just jump on your exercise bike and start pedaling.