I guess I'm brave, stupid or over confident in my thinking. From
iab 's list the thing that would stop me is the wooden rims. That is until they were removed from the spokes and refinished. Then an occasional short ride would be fun. Old tires and tubes and all else would be scrutinized but, if it looked ok, I'd ride it. Right now I have a pair of tires on a bike from the 1980"s. They were skinwall tires. Most of the latex has come off. But I can still pump them up with only one bulge which I will place a piece of silk tie material into to reinforce it. This is only temporary until I decide how much I like the bike and which specific tires I would get. I am tempted to get a jar of liquid Latex and go over the cotton cords. The rest of tire is good.
Cottered cranks. No problem.
Plastic derailleurs, well we know they have a limit life so I wouldn't go too far on them.
Galvanized spokes, yea, as long as they are not thinned out by rust.
Tubulars, yea
Steel rims, as long as they are not rusted too badly
Old freewheels, they don't make them like they used to and I prefer to rebuild them when I can, so a big yes
Old brake pads, only if they are still up to reasonable braking, otherwise replacements are inexpensive
Spoon brakes, I wish I had a bike with spoon brakes (that were original)
Old tubes, yea, I would rather patch some of the old tubes than get the new tubes with presta valves 3" (or more) long
Dork disks, sometimes they look right, like on my Schwinn Continental
Toe clips. Yes. I am using them on only one bike now. And I don't have SPD's or other shoe pedal interfaces.
Turkey Levers, Safety Lever, Extension Levers. I tried. They just don't do it for me
The "Death Fork", Aha! There it is. The one piece of old tech I would not ride. I have a Lampert that has had the death fork replaced by a Tange fork by the previous owner. Thank you Yamaha.