[bsammon]

I'd have to agree here that success at this drawing test/challenge is strongly correlated with experience repairing/maintaining (one or more) bicycles, a lot more than it is correlated with riding them.

I also suspect it strongly correlates with knowing the term "diamond-frame". In addition to bicycle-repairers probably knowing the term, it's also used among people who like/know other frame styles--in my case recumbent bicycles.