According to Fox Mill Estates, citing Virginia statute, these bikes are not allowed on our streets:

Motorized bikes are illegal on highways, sidewalks, bikeways and on hiking or recreational trails. These vehicles can only be operated on private property with the property owner’s permission.

The definition of motorized bikes:

“Motor-driven cycle” means every motorcycle that has a gasoline engine that (i) displaces less than 150 cubic centimeters; (ii) has a seat less than 24 inches in height, measured from the middle of the seat perpendicular to the ground; and (iii) has no manufacturer-issued vehicle identification number.