I live in North Orange County and most of the trails are in the South or inland. Plus, I just have to get out of the city. I remember my first year owning the Element I put about 1,000 miles on it in the first 7-8 months, but then in the summer went on a month long camping/hiking/biking road trip and jumped to 5,000 miles.
If I rode to the MTB trailheads I frequent with friends it would take a couple hours to get their by bike (vs 30 minutes in the car) and I wouldn't have the energy to do the ride, let alone get back.
As always, would love to see more bike pathways. At least Irvine (as much as I loathe it), has put in a pretty good system. It would be cool to have bike "highways".