This is a very popular cardio-machine for bike lovers. Unlike the treadmill, you remain seated all the time which many people consider as a great advantage.
Riding an exercise bike is technically easier than riding a usual bike. There is no need to keep your balance or keep an eye on the situation on the road. But it decreases the effectiveness of the training by making it more relaxed.
People with knee problems or injuries should avoid the exercise bike as it has a significant impact on the knees. Especially if the user sets the bike to a high resistance.
It also can negatively affect the knees if you select an incorrect (too low) position.
The best way to estimate the necessary load is your heart rate (cardiac rate). To burn fat you should workout at a rate of 65-75% of maximum. You can calculate your maximum cardiac rate with the following formula: 220 minus your age.