I'm with you on the speed reduction. An urban planner friend talks about how you're best motivating a speed limit by the environment (tighter road, bends, etc)

I'm with you on the speed reduction. An urban planner friend talks about how you're best motivating a speed limit by the environment (tighter road, bends, etc) rather than a literal limit and threat of fine. But how would cyclists fare on cobblestones, especially if you were talking about suburban streets with kids playing, bikes going around, etc?