SKS and a couple of other companies have gotten around this by coming out with "clip-on" fenders that can be zip-tied to a road bike. The SKS fenders are known as "race blades".
Originally Posted by randochap
(rickety "race blades" don't count)
They're a hell of a lot better than nothing! Currently I've got my old road bike set up as a commuter, and race blades are the only thing that fit on it. For what they are (a stop-gap solution), they work really well. Paired with some home made flaps and a piece on the rear of the seat tube, they work really well.