I'm less concerned with a BB being period than a lot of other things, mainly because it's not as visible.

I like the looks of traditional BBs and also that they can be adjusted, but sealed cartridge are very durable and not sensitive to hangar alignment/facing.

Those outboard bearing BB's seem like a good idea. I just replaced one, and I liked it.

Cartridge BBs are an excellent choice though I can only speak for the Shimano UN-fiftysomethings. I installed one on my early 90's racing bike and put 30k+ training and racing miles on it back then. I still have it in a box somewhere and it's as smooth and tight (no play) as the day I bought it. The plastic NDS cup was cheapish but held up well.

Myself on flips, I usually just use the UN26 BB instead. OK, they are heavier than a UN54, but they cost half as much, and functionally, I consider them equivalent.

On longevity, in my unscientific research, I have found the following:

On neglected bikes with cartridge BB, at least half are toast.

On neglected bikes with spindle/cup/loose ball bearings, less than 5% are toast.

This is with a sample of 200+ neglected bikes.

Does a $10 price difference between a UN26 and a UN54 matter? On one bike, no. On 200 bikes, yes.

Bill, that's a really good perspective. So if neglecting your BB is your mode, you want an old fashioned BB, not a cartridge.

Hey, wait a minute now. If you DON'T want to neglect your BB, you overhaul it every so often. And if it's a cartridge BB, you don't; you just wait for it to fail.

That leaves no advantage whatsoever to a cartridge BB.

What am I missing here?

That's what I was thinking......

.....But it's plug and play between many years of never having to crack open/adjust/grease your BB. I have both loose bearing and sealed cartridge bearing BBs on my bikes and I don't really prefer one over the other in the end both are good in their own ways.

Chombi

+1 Main advantage is plug and play.

And on the cost side, IF you need to replace a bottom bracket, a $10 UN26 is pretty hard to beat (assumes modern british standard threading). As a comparison, a replacement spindle at Niagara costs $5, and replacement cups cost $4.50 for the crappy Pyramid brand....

And to someone with limited tools, you go from three tools to remove a typical old cup and spindle bb, to one tool ($7) to remove/install a UN26/54.

I had some fun at the local bike shop. I went in asking to buy a spindle. Guy explained to me that they no longer sell spindles, as the cartridge bb is inexpensive, easy to install, and has replaced the cup and spindle design. So I asked him what he had available in Swiss threading. You could see that WTF moment. Priceless.

OK, I get it now. Lasts shorter, but during that time, you don't have to do anything. That's good. Fewer tools. That's good. And no guessing about what happens when you mix cups and spindles, etc, i.e. no improvising and wondering how far the chainwheels will be from the centerline. That's very good.