If you’re the parent of an elementary-school-aged kid, you’ve probably heard of a bike bus. It carries a group of children to school in the same way a regular school bus does, except everyone is on bikes. The “bus driver”—an adult on a bike—guides a slowly moving group ride along a predefined route. Kids and their parents join the group on their own bikes when the pack rolls by.Bike buses are a way for everyone to bike together for fun, convenience, and safety; on busy, traffic-congested commute...