If you can pack your bike in a car, I would go to either Ventura County,Orange County or Pacific Palisades. In Ventura County you have some great riding in Ojai. Lots of country roads. Orange County has 150 miles of bike routes along with places life Santiago Canyon. Also, almost all of the roads in Irvine have bike lanes.

Down town LA is not a very bike friendly place, but Malibu has lots of hilly country and Pacific Palisades have some great places to ride along side of the beach. Next to Pacific Palisades is Rolling Hills Estates which has lots of winding roads with great scenery.