Blackweir, Cardiff, 7pm Friday evening. Late summer sun fades to the West, scattering shadows like confetti. Freewheels tick as bikes are walked over the narrow suspension bridge. A quiet, convivial urgency informs the movement of people headed for social engagements. There are no cars here to sully the mood, hinder movement or give cause for concern. Just the empty freeway of the foot and the boulevard of the bike.