^ i'd break down your first group into smaller groups as not all recreational cyclists are "affluent".. there is a large segment of recreational cyclists in SJ who ride because it's fun and doesn't cost anything. obviously compared to the homeless these people would be considered rich but not when compared to silicon valley millionaires
but as far as advocacy groups in SJ, I'd say there isn't really much diversity. The main group i can think about is Silicon Valley Bike Coalition, which feels more like a corporation than an advocacy group. The minimum donation required to join SVBC is $35, and a $1000 donation represents a "lifetime membership". So basically this group is made up of middle class and upper class folks.
There are other bike organizations in SJ, notably San Jose Bike Party, which is very diverse. In some senses SJBP could be seen as an advocacy group, but the organizers don't seem to be interested in using their considerable reach to wield any kind of political power. They are content to use the parties themselves as a way of promoting biking, with mixed results.