Another approach would be to bike from Pasadena west though the San Gabriel valley and SanFernando Valley through the mountainous areas of Malibu to end up in PCH to go northbound. With this approach you would never go south to dtla.
This would require a lot of route planning and would be much more taxing then the above options beause you would have about roughlly 40 miles or more from Pasadena to Malibu on some routes that would be basically mountainous.