Yes:

Nothing mysterious about it. French threads are based on the globally recognized «Systčme International d'unités», otherwise known as the "metric system." That the rest of the bicycle industry chose a hodgepodge of other thread specs is hardly their fault.

Hello all...I was mostly joking, I'm aware that it's difficult to move away from your country's established systems...we'll see if this so called "systčme métrique" ever catches on. It's nothing to loose our heads over
Anyway, I had a little bit of time to (attempt) to nail down the thread direction:

left side of the bike appears to be righty tighty...

As does the right side (my fingers pointing in the thread direction)

This is why it sounds strange *to me* when people talk about the French using weird standards. The world -- other than the US -- had pretty much decided that metric (aka SI) is the way to go, so I hardly blame the French bike makers for converting to it. How did they know the rest of the world would say "never mind" in the bicycle industry?

My confusion is less on the thread size, and more about the thread direction, what are the benefits of having it be the french/Italian way?
Sounds more like a disagreement on the fundamentals of how to put a bicycle together, than a disagreement on standard tool/part sizing.

Also as vintage cellar alluded to, I think if they marked bikes with specific threading info rather than marking swiss/french the exact same and then interchanging it willy nilly (like motobecane did) there would be less frustration/jokes about french standards.
Not like im upset, the reason i want to build an old french frame is cuz i appreciate all this weirdness...but weirdness begets jokes sometimes

Threading is always an interesting subject. Local tradition plays out. There were proprietary methods that won over swaths of territory, and parts were sourced on a local basis in order to help the economies within the state. France had tariffs with Italy, neither would change, that would be a loss of face. England had a couple of different threadings with one that was eventually used outside of Europe almost everywhere before the EU was formed.

Right, some makers believed that reverse threading is important to prevent the cup from screwing itself out. Read here about precession. The cranking motion turns the spindle forwards, and precession tends to screw the cup backwards. Reverse-threading the right-side cup prevents that. Precession will tend to screw the cup even tighter.

In post #27, Charles Wahl infers that some makers didn't think it was important because you can mitigate the risk of precession by screwing the fixed in very tight.

Interesting that pedal threads are always reverse-threaded on the left pedal (i.e. the pedal you put your left foot on); there is no disagreement on that. And fun fact: the Wright brothers came up with that idea. I don't know why we got a consensus about pedal threads but not about crank cup threads. Maybe making taps was prohibitively expensive so they wanted to use one tap for both sides. Nah, I wouldn't buy that if you claimed it. Those taps wear out, and if you use a tap half as frequently, it lasts twice as long.

Personally, I find the metric system to be far more "rational" for bicycles than the English (Imperial) one. We routinely use mm for hub spacing, wheel diameters, stems, handlebars, tire widths; and even express "inch" as 25.4. So why not refer to 1.370" x 24 TPI (a weird dimension anyway) as M34.78 x .95 mm for bottom brackets? At least it provides a frame of reference on a par with all the other standards.

An advantage of using the same thread on both sides of the bottom bracket is that the shell can be threaded on a lathe, simply running the tap through from one side all the way to the other. Dave Tesch told me that was why he liked using Italian thread on his frames.

most of the French and Italian thread BB shells i have seen are not done all through.
Although Pino expected you to be capable of that. A Var tap would be needed, Campagnolo / Cobra ... no dice.

I would have to check my S-22, Beef, its what's for dinner.

Hello all!
I appreciate all the input I've received, thought I'd share some progress:


I will try to post updates, unless there is a better place for that sort of thing.
Santé!

Hello all,
I have managed to source a very nice campy bottom bracket, 112mm spindle french threaded etc. Photo of the spindle part no 68-SS-120:


I have successfully installed it on my bike (along with some snazzy Mavic wheels) and so far it fits!:

Clearly french threaded, and my joy is immeasurable! The last thing to do before i can declare victory is ensure the chain line is good. Looks pretty good to me:

but who knows, I will go to my LBS to pick up a chain and will report back if they laugh at me for my crooked chain-line.

Hello all!
Thanks for all the help during this processes, couldn't have done it without you! Here is the finished bike:

Oh man is it fun! Put some 26mm turbo cottons on it, and spent yesterday doing powerslides in the various piles of leaves on the road. I think the blue tape really goes with the silver/Grey and the tri-colour motobecane badging.
-Hank

Hi all,
Id like to update yall as the bike has been in its "final form" for a while now and ive had a chance to take some better pictures:





Settled on a nitto pearl stem (sanded down a bit to get it to fit in the fork, but worry not i went through all grits/polished it like a good boy before i was done) and some nitto rando bars. Bag is an old hand me down from my dad, as are the front panniers.
a very comfy, fast ride indeed; and it can carry many dozens of eggs to boot.

Cheers,

Hank