Hit up Nevada City area and rode some of the lower trails below Whitecloud campgound. You can ride most of the way to Skillman campground on the Pioneer Trail but there's snow above that.... for now. It should be noted that the Pioneer Trail between Harmony Ridge Market and Whitecloud is just so-so. However, the trails that spur off the Pioneer in that area are fabulous! We rode Scotts Drop, Miners and some others that I can't tell you about.... you just had to be there. The Pioneer ABOVE Whitecloud Campground is super neato with, yet again, more options.
This guy has some good/basic mapage that will get you started down there. It's a nice alternative to Auburn with less people (usually), more trail options and a shorter drive. The town of Nevada City has all the amenities a mountain biker would need from greasy bar food to fine dining and everything in between. Personally, I like the hippie burrito shop on the north side of town.