Pretty much anything not covered by the topics above. Short lived production bikes or vehicles, Electrical, Tires, Paint, Brakes, etc. Use this for tech questions, and "Shoot the Bull" for general conversation, no tech.
Looking around I see that Avon do the Cobra in a narrow 23" size, although they don't seem easy to find. Chang Shin list a trials type tyre.
I was just curious; I'm familiar with the Barum 2.25x 23" track racing tyre that is still in use in speedway and grass-track, and I know all about the various 21" types from the Avon Speedmaster to the motocross ones but I've never actually seen a road bike with a 23" front wheel, although they must exist, it seems. I've seen occasional bikes in the "board tracker" style with no brakes and speedway tyres, but I'd always assumed that as the whole bike looked unrideable, the tyres used were purely cosmetic anyway
Shoot, a man could have a good weekend in Dallas with all that stuff...