As Hobbit said, you need the rails.Ive had the throw overs for many years, adding/removing the rails for trips.If you can live with the rails they work just fine, make sure to pick up a nice piece of soft leather to protect the paint.Also found tieing the bags to the rails with leather laces to be a pain.After a couple of uses I went with zip ties.Pack a couple of extra zip ties so you can cut them for removal and reinstall much faster than dealing with the long strings.Adding/removing the rails can be a pain as the bolts required for install are longer and may require lifting the bike to clear the rear tire.Another note of caution if you choose to add and remove the rails for trips only.Even though you may convince yourself they will only be on for a short time dont forget the locktight.Lost a nut on one of mine which I noticed only when the smell of burning rubber caused by the bolt burning into my rear tire.