If there is one thing the Irvine area is not short on, it's paved trails. Depending on where you start, this either comes off the Back Bay Loop Trail
or you can access on the other side of the 405 from the Irvine Spectrum Center.
On this trail, you hike through industrial areas, neighborhoods, and even the edges of the university campus.
As with other trails in the area, keep a watch for cyclists--but enjoy the solitude and the views you get along the way.