If you decide to go up to Sacramento to ride the American River Trail, you might consider taking Amtrak up there. They have bike racks on the train and the station in Sac is right by the trail. You can even bring a bag and check it at the station, so that after your ride you can, check your bike, take a little *****'s bath in the washroom, change clothes, and hunt down something yummy in Old Town Sacramento.
Nice way to spend a Saturday or Sunday!! And it's usually warmer there than down here.

No cars for 25 miles!!