Time to go back to the Miyun Lake for a few laps. The A ride do a nice long loop around the entire Miyun Lake while B and C group will travel along the Western side. C and B group will see the Great Wall up close.
For the wind geeks here is the wind forecast for the next 9 days. (only works with VPN on). This was developed especially for predicting days which were suitable to ride by friend Dustin Grzesik in 2013. Infact it was one of the first wind prediction tools (if not the first) in Beijing. We use it religiously to predict the quality of the air in the city and out in the mountains. If the wind is blowing from the North and over 10kph expect an AQI of under 50 in the city. With less windspeed its often also excellent quality air in the mountains.
You can use this data to decide when to ride and understand Beijing's wind and pollution patterns.