We rode pavement from Oregon to NM. I did a bit of research. Here are the highlights off the top of my head. South on US 1 thru redwood forest, then over mountains to Redding. Then down to Lake Tahoe along west side, Then down to Lee Vining CA. Then over to Tonapah NV. Then Warm Springs, Rachel, Caliente NV, Cedar City Utah. Over mountains and down to Kanab. You would probably want to stay north somewhere along in here to get to CO.