NY 86 begins at NY 30 in Paul Smiths, Franklin County. The route heads east through the town of Brighton, providing mountain views of Adirondack Park. After passing through the tiny communities of Easy Street and Gabriels and traversing the southern edge of Paul Smiths College, NY 86 turns south to serve Harrietstown, where it meets NY 186 at the hamlet of the same name. NY 86 continues southward to Saranac Lake, the largest community on NY 86 in Franklin County. Moving through Saranac Lake, the business and tourism anchor for the area, NY 86 is well marked, but follows local roads to an intersection with NY 3 in the village center. The routes briefly overlap before splitting at the northern edge of Lake Flower.