Justin- Have you not seen drop out adjusting screws with the knurled or wing form on them? The idea is two fold. One is to have a nice flat surface to butt up against the axle, like the screw's head allows for. Second is to let the rider be able to move the screw with out a tool. The little chromed and knurled "nut" (or the plastic wing like tab) threads onto the end of the screw, sticking out past the drop out, and makes turning the screw much easier. These screw end cap/nuts often rattle off the screw, and like that PV adapter on the valve, go missing. One of my anilities is to tighten the cap really well when I work on a bike with them.
>I joined the list today, having lurked off-and-on for several years. I
> a small question about dropout adjustment screws. Why do they thread
> through the dropout from the front to the rear? It would seem more
> to thread them from the rear to the front -- that way the screws could be
> adjusted without removing the wheel. I am sure there is a reason for
> I just don't know what it is.
> Justin Miller
> Philadelphia, PA