Figuring out how fast you want to lose pounds can help you determine how many calories you really want to burn by bikes directs and in turn, how long you need to pedal for.
Choosing to exercise on a stationary bike at the gym, will allow you to exercise in absolutely any weather, as well as help you monitor and keep track of your speed more accurately.
Moderate intensity would be a 7 or 8 on a 1 to 10 perceived exertion scale, and vigorous would be close to a 9 on that same scale. Keep in mind that the harder you work, the more calories you will burn and you will lose weight faster. Your goal should be to burn about 3500 calories per week minimum.
Do you prefer to ride on pavement, trails, uphills/downhills, or will you stay on a level ground? Regardless of the type of bike you decide to get, be sure to purchase a quality well-fitted helmet, which is very important.