just as a comparison though, the Axiom streamliner using skewer can be had for under $40 and it is perfectly sturdy. I guess if you put a rack on that doesnt use the skewer setup, then its always a bit easier to take off the rear wheel, so any rack will thread into the holes in that frame at the bottom, you just have to find to hardware and whatnot for the attachment point at the seatpost area.

**I would add that some racks have a diff distance between the two lower parts, where the bolts go through, maybe check with a given rack that the rack is not putting too much force on the frame at the bolt hole area--this was the case with mywifes bike, even though it has bolt holes at the dropouts, the axiom rack needed to be spread really hard to get it to go onto the frame bolt area (which was rather wide at that hole place) and Ididnt like the force it was putting there-maybe I could have bent the rack supprts out more, but I just went with the skewer option.
I do know taht this axiom rack is put on carbon bikes successfully, although they would have road brakes, so the single attachment point goes onto the brake bolt and nut, like on mywifes bike , and it works fine there (not the case with this bike I know, iwth discs)