This is probably a dumb question, but i thought i read somewhere that you can use a 68 mm bb in a 73 mm shell? Yes/No? Or was it the other way around?

The threading for ISO 68/73 mm bottom brackets is the SAME (as far as I understand), it's just a question of how far the cups stick out from the. Sheldon Brown sez: https://sheldonbrown.com/gloss_bo-z.html#bottom

Not one that I've ever tried. The test would be if the left crankarm hits the chainstay. Depending on the crank it might work well enough to be rideable, but I think that it's kind'a nice to have the crank centered on the frame.

It would depend on the length of the spindle I suppose... and the amount of adjustability available in the cups.
Ranger, if this is an old adjustable bottom bracket, the cups are certainly interchangeable between 68 mm and 78 mm shells--provided that the threads match.

You're right. Goes to show how long it's been since I did anything with a bottom bracket that had separate cups.

Am I really out-retro-grouching you? 2 out of my 3 bikes have adjustable BBs, mostly cause I'm cheap and they worked fine when I got them.

I'm a retro grouch, but not a reactionary grouch. I'd hold onto an adjustable BB until the spindle bearing races pitted or something like that, then I'd swap it for a cartridge in a heartbeat.

Agreed. Just hasn't happened yet for me.

HEATHENS!!!

HERETICS!!!

SARACENS!!!

Cheapskate right here. I also enjoy playing with loose ball bearings and the ability to flip a spindle around.

I loved my old Campy bottom bracket. It was lightweight and beautiful. But I rode on it for over two years and when I pulled it out, it was rusted and pitted.

Since then I've pulled the BB out every 500 miles and cleaned and regreased. I was especially diligent during the rainy season. That practice became tiresome quickly and now I use the heavier cartidge bottom brackets and don't worry about it anymore.

Yup. I like cassette freehubs much better than spin-on freewheels too. Oh, and I think that down tube shifters are like having the gear shift located on the running board of your car.

I'll agree that cassettes are just plain better. My road bike has downtube shifters and I've never used brifters... but I like downtube shifters just fine except when going slowly and it's hard to balance.

I find it very relaxing actually, and extremely satisfying when you get a nice old Nouvo Record BB to spin smooth as butter. Modern cartridge BBs never do that.

But they are a lot easier. I have them on all my MTBs.

Because of the seals?

Agreed, it's a fun challenge.

They are equal or better in basically all respects I'd say. But when they break, they're broken. And I find that extremely frustrating. I like to be able to fix everything, even if it's not really worth the time and effort.

I heard that Phil Wood makes fancy cartridge BBs with replaceable bearings that press onto the spindles. In my opinion that is the way they should all be, basically a cup and cone but with sealed bearing cartridges. I'd buy one but they are soooo expensive.

On my older Giant I have a 73 mm shell and have been running 68 mm BBs for years. It works better IMHO since it runs the bearing in deeper in the frame. Thus it keeps a good bit of crud out(which we have enough of in east coast racing). Ideally the bearing would be placed like the external cup BB(X-type, Hollowtech II) to keep the load spread wider, hence more rigid, but the difference is minimal. If you run a 68 the only concern is your spindle length and if the left(non drive) cup has a shoulder. If it does have a shoulder than it can't take up the slack propperly, in which case its no good. A lot of models are non-shouldered. Adjustible is the way to go.