I'm at home with a four year old, and am trying hard to make bike the default choice for most of my journeys, which are typically less than 5 miles round trip. This has been achieved with varying amounts of success, I'm not great at loading her into the trailer on icy or wet mornings for example, and as Mickle says, it's just too convenient to use the car. I am getting better though, and the more I do it the easier it will get. There is no contest between bike and car, I prefer being on the bike whenever I can.