If you want to factor this in, there are several of us that ride the metric portion of the Tour of Napa in the fall or when the whim strikes us. The fall is a much nicer time to ride this route. August is OK but it's nicer in the fall, winter and spring. Anybehoobe, we can always plan a group ride on our own.
If you do a search for past group rides, look for "Twist on the Tour of Napa" or something like that. We start in St. Helena instead of Yountville and descend Howell Mtn cuz it's nicer.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.