Wrong on so many counts, but being a building anorak I diverted to studying the brick bonding, a perverse variation on English garden wall bond...
Now does it mean what it says, no dogs riding bicycles, or is it suggesting its a bicycle riding area, so no dogs, or no bicycle riding, because dogs are allowed. I'm always amused by signs referring to "no bicycle riding" as it only encourages trikes and unicycles, and quadcycles, and....
Referring to "cycling" would cover all, and saves on paint. As you say, silly sign...