A new bike, sized right, a quiet cul-de-sac, and an experienced friend who’s a wheel-radius ahead in cycling development make for an afternoon of colossal advances in biking. The radius ahead, however, was often a radius to the right, to the left, a radius behind.

Much to the Girl’s consternation. Five year olds together, best friends, are often like an old married couple: constantly arguing, but inseparable.