Cafe curtain rods are similar to sash rods except they are frequently available with a larger clearance and some styles are more decorative. As with sash rods, cafe rods are designed for use with extremely light weight fabrics or sheers. If your drapery is lined or interlined, or if you need a rod that's wide, a standard curtain rod or a decorative drapery hardware treatment is probably going to be a better option.
If your curtain has a rod pocket, you'll need to consider the pocket depth when choosing a cafe rod. These rods are measured by their outer diameter. Make sure that the rod pocket on your drapery is large enough to comfortably accommodate the diameter of the rod. For decorative cafe rods, you can use small rings to attach your fabric to the rod. Rings with alligator clips are a popular option, and you can always stitch rings into the top of your drapery.
While some cafe rods may extend into the eight foot and over range, you must use extreme caution because the diameter of these rods is very small. They're not going to do a very good job supporting fabrics with a floor length drop. For toppers or valances of this width, where the fabric drop is around six inches or so, you'll most likely not notice any bowing or sagging.