Eagle River, WI (KDAL) - In the Northern Wisconsin Community of Eagle River this weekend the owners of vintage snowmobiles will bring out the sleds for a series of slow motion races that are a prelude to next weekend's World Snowmobile Championships.  While about three to five thousand fans will be out this weekend, organizers of the AMZOIL World Championship Snowmobile Derby expect upwards of twenty thousand fans for the faster races next weekend.