Preheat oven to 350°F. In a large mixing bowl, whisk the flour, sugar, baking powder, baking soda and salt; set aside. In a small bowl, stir together the milk, mayonnaise and apple cider vinegar. Pour into the dry ingredients and gently mix to combine. Spread the dough evenly into the loaf pan. Bake on center rack for 45 to 55 minutes.