I commute daily through Rock Creek Park, from Dupont Circle to Silver Spring. I use the road north of Broad Branch Drive, but I’m going against the flow of most of the traffic, so I don’t have as many cars passing me. I do see a fair number of cyclists going the other direction. The road is in sad shape, so if you are comfortable riding in traffic, don’t be afraid to ride towards the middle of the lane in places where the potholes and patches make the right side too bumpy.
From the CCT, you can either turn right on Jones Mill Road and take that to Beach Drive, or you can go left and take Susanna Lane to the Rock Creek trail connector. See this map as an example. From the District line to Bingham Drive, you’ll be on the road. There is a parallel bike trail from Bingham Drive to Joyce Road. If it has rained heavily recently, there’s a bad muddy patch on the trail just north of bridge over Rock Creek.
At Joyce Road, you can continue on Beach Drive south, but I like turning right and taking Ross Drive to Ridge Road to Broad Branch Road. It’s some nice hill work with hardly any traffic. On my commute, I can count the cars that I usually see in a week on that segment on one hand. From Broad Branch Road, you can take the trail to Pierce Mill and beyond.
The road is closed south of Pierce Mill, but that is going to reopen soon. The next section of road to be closed will be from Joyce Road to Pierce Mill. As I understand, Ridge Road and Ross Drive will be closed to cars during this time period.
.