Kirk R from Brunswick, MD on 1/6/2022 6:41:26 PM:
I would personally spend most of my time on mountain rd, which is a low traffic, nicely paved, road. It does have a good long climb on it, which is a big contrast from the tow path. Here's a route I made for someone (on this site, I think) and have used: https://ridewithgps.com/routes/35184094
There are a lot of gravel/dirt roads in loudoun county. It's one of the things that part of the county it known for (and there are efforts to keep them unpaved). You can zoom in to loudoun county on this state-wide map to see some of it. I have not verified that it's accurate (I live here so I just ride and see). https://vdot.maps.arcgis.com/apps/webappviewer/index.html?id=e4e9638690634fafae8bccb63abbee7c