Yorba–Prado Dam Pronto Professional Review and Guide
"Saving the best for last? Well, Yorba-Prado Dam Pronto is the longest ride in the book by just under a mile, at 46.8 miles.
The route is a giant, clockwise loop that passes through three counties (Orange, San Bernardino, and Riverside) and six cities (Yorba Linda, Brea, Chino Hills, Chino, Norco, and Corona). The route is the shortest way to loop the Chino Hills and Prado Dam by bicycle, where there are no shortcuts."