The Columbia Trail is actually the old railroad line north from High Bridge. Great scenery and just slight a slight grade in places, some parts are rocky and crosses a couple refurbished bridges. Leaving High Bridge you follow a river about 50 feet below the trail - great views. About 5 miles up you'll go through the town of Califon, and another 3 miles past that you'll have to find your way across Route 513 to the rest of the trail that ends in Long Valley, this portion of the trail is not marked as well. Basically a fast, flat ride with some nice views.
How to get there:
78 to 31 North (Clinton Exit). Take 31 North a couple miles to 513 North in High Bridge. Stay on 513, make a right into High Bridge and then a left a the top of the hill on Main street. The trail head is clearly marked a couple blocks up on your right.