Catamount Outdoor Family Center
The Catamount Outdor Family Center has been offering mountain biking since the 80's. It later developed Nordic Ski trails. Making it one of the first areas to have both.
Of course that was long before anyone ever heard of a Fat Bike. Which now share the trails in the winter months.
The center has over 20 miles of well maintanied trails. You might think that the trails are flat.
Well, some are pretty mellow but there's a 600' hill on the property and the trails make good use of it.
No matter what the season, in you're in the area, check out Catamont. In season they offer bike rentals, lessons, rides and races.
Here's a description from their Facebook Page.
":The Catamount Outdoor Family Center (COFC) in Williston, Vermont, provides activities year round including mountain biking, hiking, snowshoeing, cross country skiing, fat biking and sledding. In addition, COFC is known for the variety of events held throughout the year including a weekly race series and a summer camp program."