I ride the section from Santa Cruz north all the time. Go all the way up past Point Arena and cut across at 20. This takes you north of upper lake and across 5. Then take the 49 turnoff from 20 when you get to Nevada City. Up through Downiville and back to Truckee. Great ride but you might want to split it in two. Early morning fog on the North Coast can make things a little slick and they use coral to sand the roads in the coastal mountains. No sun gets though the Redwoods so watch out for slick spots. Also on the North Coast watch for the logging trucks.