I'm sorry, I don't know what you are responding to with "Probably bikes right?". Cities that are built for living typically include massive investments in pedestrian infrastructure, including bikes, if that is what you are saying. Biking is not feasible in most suburbs because of the distance. Cities that care about reducing traffic, such as Amsterdam, absolutely have more children biking than a suburban area. Unfortunately a lot of cities in the United States were built for cars and not people.