If you're looking for a slightly flatter route, you can avoid Jamboree and Cannon. Irvine Blvd, R on Redhill, L on Skyline, R Newport, L 17th, R on Hewes, L Santiago/Villa Park, R on Wanda/Santa Ana Cyn, L Gypsum to the SART.

I've ridden all of these streets and they are decent for bikes. The climbs on Cannon and Jamboree are good, I do them, just depends what you want.