Insofar as I know, a retrogrouch is, and has been for many years in this club, a rider who persists in favoring old componentry and old ways of thinking about bicycles.
...Someone, say, with downtube shifters and toe clipped pedals, or a frame of Columbus steel. Maybe SunTour brakes. And a freewheel, preferably with six speeds.
That's not me. Granted I think all bikes are pretty much the same with their major difference being perception fostered by that most devious of arts, advertising; and where there is an actual product distinction, I think way more often than not it's meaningless to the ride and performance.
That said, one of my bike frames, although made in 1991, was literally under my bed, unbuilt, for its first 11 years, so it's only four years in use; the other is three years in use.
Granted I was among the last to go to combined shift and brake levers e.g. STI and Ergo, but I've been there since 2002. Granted I was among the last to go to clipless pedals, but I've been there since, I think, ca. 1990.
So where's the retrogrouch in all this?
As for my being a grouch, well, that's an entirely different matter.
As, I see on the home page, Evan tied with me, perhaps he and I should have a bi(t)ch-off.
NOTE: The above parentheses is to get around the site's auto-censor for profanity.