You already know you feel good when you ride a bike. Regardless of how, what, where or why you ride, you're experiencing physical and mental benefits.

For example, the simple friendship we experience by riding with a group of people is linked to the release of the hormone oxytocin, which helps reduce blood pressure and build the immune system, one of many important health benefits. Similarly, biking for transportation appears more helpful in losing weight and promoting health than working out at the gym.

Why biking to work is great for your health (Alliance for Biking & Walking)

Parents play a vital role in encouraging bicycling among their kids. There are a number of research studies that demonstrate significant health benefits for children who walk or bicycle to school. For example, a Danish study in 2012 show that children who walk or bike to school rather than being driven by their parents have increased concentration, and the effect of this ‘exercise’ lasts all morning.

Mental health

Aerobic activity such as bicycling is recognized as a defense against everything from depression to addiction to menopause to Alzheimer's. Bike-riding has been studied for its effects on mood disorders, Parkinson's symptoms and more, and there's anecdotal evidence of beneficial effects on ADHD in children and adults. Bike commuting in particular is associated with a sense of well being that suggests that bike commuters are happiest kind fo commuters.

Bicycling and Mental Health (Girls Biking to Work)
The title pretty much says it all. An overview, with many helpful links.

As a tool for maintaining a healthy body weight, bicycling makes us happier, relieves stress, helps us sleep better, and more -- and all that affects how we store and burn fat. The Harvard School of Public Health conducted the first study that demonstrated these benefits specifically for women.