I'm calling this bike ride "Boulder 720" by analogy to the Boulder 360 ride. This is about twice as long, so the number used to describe it must be twice as big. I live in Longmont, so I drove into Niwot. The dirt paths east of Boulder were passable with my entry-level road bike; only the North Foothills Trail on the north-west side of town was impassable by my bike. This route is also available as the raw track (kml) and the GPS route, rounded off to the nearest 100 feet (gpx).