Girl chases grandfather on bike

We walked down the street at my parents’ house, where my dad was riding his bike. Shira thought it’d be cool to follow him home, and she meant follow, right on his tail. So as he started home, pedaling as slowly as he could while still keeping upright on the bike, Shira trotted along beside the back wheel. I moseyed along behind, wishing I had my camera, but instead I took a mental snapshot. What is it about bikes that’s so special, so linked to childhood and growing up?