http://www.penvelo.org/ Group rides Sunday and Saturday morning and I believe Wednesday evening starting at Canada and 92. I think the A ride is Sunday and B ride Saturday.
My club.......
http://www.altovelo.org/ Group rides Sunday and Saturday morning starting at Peet's Coffer in Los Altos. The A ride is Sunday and B ride is Saturday.
I live near Burlingame and there are several excellent routes leaving Burlingame to Canada Road where you can ride to Los Altos or to the coast over Skyline. Here are some routes courtesy of Velogirls....
http://velogirls.com/resources/routes.php#peninsula