This is a great ride mostly along two big rivers. The starting point is just there to show the only choke point along the way east. Once on the Wenyu river (温榆河), it is a bike only road all the way up north, except for a passage where the Song art museum is located.
You then have to cross a big junction of roads, but it's light traffic controlled. Then you follow a wide paved road leading to an international school, before the annoying part, the Jingmi road (京密路). It's annoying because of the traffic and noise, but once you cross it, the cycling lane is twice the size of a road lane.
Go south over the river to the next traffic lights and head back north to find the river road.
Follow the river for as much as you wish, it's all cycling only from that point on. The itinerary shows a way down back to the starting point. Although it is a big expressway, there is a side road with cycling lane as almost always in Beijing.
The last part of the ride goes to Chaoyang Park (朝阳公园) just because most people would come riding from this area.
NB: At the time of writing (sept 2022) some paths west of the starting point (north or south of the river) might be randomly closed for some unknown reason. As it is also a car lane there, if one is closed, the other is ok. East of the starting point is always ok.
The whole ride is great. It is quiet, the tree shade and water prximity allows you to do the ride even if it's hot. Along the Wenyu river, there are some smallish hills and twists in the road, and usually two different diverging and then converging roads that meet later.