This video prominently notes that Dr David Hon is a physicist. No more evidence for this is needed than the fact that he is wearing the same hairstyle and camel coloured blazer as a cash-strapped entrepreneur in 1981, as he wears in a number of videos shot in the late 2010s, when he was a multi-millionaire plutocrat. We physicists know not to expend unnecessary energy on making purposeless changes.

• Publisher: Dahon
• Country: USA
• Date: 1981?
• Derailleur brands: Dahon, Tern
• Derailleurs: none