OC_Roadie asked how far the trail goes: The part that follows the river pretty much stops at Green River, however you can take Green River into Corona and then on to Norco, Riverside, or even Ellsinore. The Riverside Bicycle Club has an annual ride called "Smog to Surf" that goes From Riverside to Huntington and back for a full century. I think you can still sign up for the August 27th ride.
Casey