No No!.. You need to think about this from a marketing perspective.. the granular size of that^ surface according to the Udden-Wentworth grain scale would be too large to be considered gravel.. so these bikes can't be gravel bikes, they need be recognised as an entirely new marketable catagory of off-road bicycle with a new set of standards. A cobble would be considered as being between 64–256mm .. which would make them cobble-bikes, capable of riding loose surfaces between 64–256 millimeters.
You heard it here first people!