Preheat oven to 350 degrees. In a large bowl mix together sugar and oil. Blend in egg, vanilla and buttermilk. In a separate bowl combine flour, cinnamon and baking soda. Add the flour mixture to the moist ingredients. Stir in rhubab and nuts. Divide batter between 2 greased loaf pans. Bake 45 minutes or until cake tester inserted in middle of loaf comes out clean.