Bikes can go waaaaaay north. At least to Mata Chica, that I know of. Mind you, it is not a paved bike path.
But it is the ONLY path. Sometimes it is just riding on the beach. Last week my friends (2 adults and 2 kids) rode all the way to Captain Morgan's, who was nice enough to let the kids go in their pool while mom and dad relaxed with beverages. (I'm not advertising that Captain Morgans has a "free pool" for everyone-- just that they took pity on the tired and hot kids that day, which was nice, I thought.)