My perspective on the original post was a thought on how to get faster, if one wanted to. It also sounds like someone made an unfortunate remark about 13 mph being slow, which as everyone has pointed out, doesn't mean diddly.

But I'm definitely interested in going faster - when I'm out by myself, strictly for personal satisfaction (or maybe to try catching some of those groups who pass me). What I'm concentrating on is form, and noting my speed on sections of my ride that I repeat all the time. Like, "hey, weren't we doing X mph last week, and now we're up to X + 1." And from what I can tell, proper form involves moving your knees up and down, and not moving anything back and forth or side to side. If this can be accomplished, then all the effort goes into moving the bike forward. And someday I'm going to ride up a HILL - I promise. I'd like to be able to do this without hurting my back... so Form is an interesting topic to me. But this sort of stuff floats my boat, and doesn't mean a thing about anyone else.