Sacramento is not the Bay Area- it is in the Sacramento Valley. I haven't lived in Sacto in a couple of years but they have a well developed cycling community.
I used to see quite a few rides leaving from City Bikes on most days in team kit. There are two large clubs in the area: The Sacramento Wheelmen
and the Sacramento Bike Hikers
. I never road with the Wheelmen but they were rumored to have some competitive hammerfests. The Bike Hikers were more family/newbie oriented and rode at appropriate speeds. The Bike Hikers encourage guest riders but I don't know about the Wheelmen. Additionally, ad hoc groups form every weekend on the American River Bike/Discovery Trail of every caliber- although there is supposed to be a 15mph speed limit on that trail (watch for the stroller brigades and other oblivious and slow traffic).
The best source of information would come from the local shops or local racer there. I'm sure groups leave from some of the other bike shops or the bike shops have information about such training rides. Some of the shops are pretty serious about racing- especially Bicycle Business
which sometimes has a Discovery Channel team car parked out front.
Sorry I can't help more.