No surprise here that cycling is healthy, it's especially good for your cardiovascular system and it's low impact makes it healthier for the joints than running...However, cycling is not a weight bearing activity and doesn't do anything to increase bone density and doesn't do anything for your upper body strength. Cycling isn't a substitute for weight lifting and gym work.. You should also do some resistance training to strengthen you joints, increase muscle mass and increase bone density to prevent osteoporosis in older age...Also if your diet is poor and you eat like crap then you won't reap any health benefits no matter how much you ride or exercise.