This is Minnesota Off-Road Cyclists. They build and maintain trails all over the Twin Cities. There are trail conditions and some are open during the winter. I ride Theo Wirth a lot but Lebanon Hills in the SE metro is the best, most fun, trail I have ever ridden.
Battle Creek is good. For novice or intermediate riders, the trail along the north bank of the Minnesota river is always a good choice. It's accessible from Lyndale Ave, I believe.