I have several theaded holes in my steel-framed Lemond and since there is no paint in there on the threads, this seems like a place rust could start. These holes appear to be for fender mounts (not the vent/drain holes). My other bikes also have rack mounting threaded holes in addition to the fender mounts.
Do other people put a screw in the hole even if it is not being used?
I have put some grease in the holes on my Lemond for now, I was thinking plastic plugs are also a possibility.
What do you do?