You see all those wonderful yellow lines? Those are roads that are not paved. Either gravel or dirt and they are public. Some are only a few miles long but others like the one below are hundreds of miles long.
What I love about this website is when you click on a route you see the elevation change and the other valuable information. The website appears to be made by Mountian bikes but it serves a purpose for anyone wanting to find routes near by or thousands of miles away that are unpaved. The website appears to be community based so anyone who has info to add I’m sure the contribution would be welcome!
Here is the link to the website