Question: My doctor told me to do aerobic exercise five times a week. Should I ride a bicycle, jog or walk fast?
Answer: In terms of recommendations, the doctor may recommend a variety of exercises. Whether or not you ride a bike obviously depends on whether you own one, and where you live, and what the opportunities for exercise are. So I would say, choose the exercise that's convenient for you and safe.
If you live in an area where you can ride a cycle and enjoy it, that's great. Use the correct protective gear. If you're in a high density area where cycling is dangerous, you can get the same benefit out of walking, vary it, go up and down stairs, consider a treadmill or an exercycle. All of these are quite good for you in terms of aerobic exercise and benefiting your heart.