Google Map It, most of the roads out of there are bike friendly, as long as you are a safe rider. I googled "Chestnut Hill" it looks to be in the Carmel Mnt/Sabre Springs area (fancy names for the development of the area between Poway and Skinurpeenus), my route suggestion would be to head slightly north to Camino Del Norte, take that west through 4S ranch, it will turn into Camino Del Sur. Turn right on San Dieguito road, right on El Apajo to Via De Santa Fe up into the heart of Rancho Santa Fe, then Linea Del Cielo west until it turns into Lomas Santa Fe all the way to PCH in Solana Beach. North or South from there your choice. South takes you through Solana Beach and Del Mar you can pick up Carmel Valley road back east to the 56 bike trail for a nice loop or continue south to take on either the Torrey Pine Grade or Park Road, once at the top then loop back to Carmel Valley and back to Poway/Penasquitos area.
or, up in Rancho Santa Fe head east along Del Dios and loop back through Harmony Grove ( I know the way, just not the actual street names off hand) and back to the coast along La Costa Avenue than back south along PCH through Encinitas/Sol Bch/Del Mar and back east as mentioned above. If you are up for that route than you will have experienced the San Diego North County Coastal Biking Nirvana.
Last edited by atmdad; 06-13-12 at 11:37 PM.