Some guys here may remember RJ on the VRCC Board. RJ was a retired CHP Motorcycle officer. He always advocated for the idea of a flap on the front to cut down on rear flats for the very reason you mentioned. He said that the CHP put mudflaps on their motorcycles for that very reason and after over a million miles on bikes, he strongly believed the theory of the front kicking up the debris and the flap keeping it from getting into the rear.