Try the area along Valley Circle.
I did a run there about a month back. There is a small bike line starting in the north, and it can be a bit dangerous. But, it'll take you from the north valley (118) to the south valley (101) and rides parallel to Topanga Canyon. Once you get out of the first parts, Valley Circle opens up and rides next to homes. There bike lane opens up, and there are a few hills you can go down. I didn't get stopped too often, and had a good time.
If you're a little more advanced, you can even try Box Canyon which is in the same area. I've only driven it when I was younger, and from what I can remember, it's pretty hilly.