If you are starting at Roosevelt Park and wish to limit your time in traffic take the Greenway Trail (pavement) off of Boston. Follow The Greenway Trail west to Airport Road (pavement). Turn Left on Airport Road to Nelson Road and turn right to rejoin the route. Currently the Greenway Trail is under construction that is about finished. For a short time you may have to take Boston to a left on Sunset Street. After crossing the St Vrain River get on the Greenway Trail there.

If you are not starting at Roosevelt Park in Longmont you can detour at 83rd Street and Highway 119. This will cut most of the pavement off the loop and a few miles. Cross 119 and turn south/left toward Boulder. After a very short shoulder ride turn right onto Oxford Road (gravel). The next right is 81st Street (gravel) and follow this to a T. Turn left and go through a gate to a right turn onto 79th Street (gravel) to Plateau Road (gravel turning to pavement) and turn left. Just after you hit pavement turn right onto Portico Lane (pavement). At the T turn left and follow to the next left. This leads to a traffic circle. Take the first exit from the traffic circle to Clover Basin Drive (pavement). Turn left on Clover Basin Drive to 75th Street and Pike Road (gravel). This is the Open Sky parking area. Further west and to the left is Lagerman Reservoir.