i have a late 70s motobecane frame. It has a french BB. Ive removed the fixed cup and go to thread in my new cups...and they wont go.

I can thread the fixed cup and the adjustable cup in the non drive side no problem. The fixed cup that i took out goes right back in with the counter clockwise thread like it is suppose to on the drive side but i cant get it started on the adjustable side. were the threads per inch or pitch different on the non drive side fixed cups? I have never seen this before and ive done a peugeot with great success.

if i hold up the new cups over the threads of the old cups...they appear to match up thread wise just fine. I dont get it.

The new cups i have are 35xp1 french threaded.

ANyone?

UPdate: I found this.....

All cups on the non-gear/left side un-thread in the direction the crankarms move while pedaling

French fixed cups (gear side) un-thread in the direction the crankarms move when pedaling backwards.

Swiss fixed cups un-thread in the direction the crankarm moves while pedaling forwards.

British fixed cups un-thread in the direction the crankarm moves while pedaling forwards.

Ill bet it is Swiss...
when i thread in the original fixed cup i have to thread it in going in a counter clockwise rotation (same direction as the cranks going forward. It THreads right it.....

SO....looks like i have a french bb for the parts bin.

Funny...the damn bike says MADE IN FRANCE right on it in big bold letters so i figured it was the same as my peugeot....

Hmm, could be Swiss threaded. Same size as French, but fixed cup is left threaded:

https://sheldonbrown.com/gloss_st-z.html#swiss

Neal

i think you are right . I found the answer about the same time you replied.

Now to try and source a set of cups....or at least a fixed cup. It appears they are pretty hard to locate. Is ebay the place to go for this type or can they be had online somewhere? Not looking for the Phil Wood model That is a bit out of my price range ....to say the least.

So the existing drive-side cup is trashed?

Neal

nah...it is fine. Perfect in fact. THe problem is they are thin walled cups because the previous setup had cottered cranks. IM moving toward a square tapered spindle at this point ...or thats the goal. I tried a #3 spindle and it is close but just not quite a fit because the thin wall cups thread in too far and you cant get a good deep bite with the lock ring. Conversely......i think a #5 spindle will be a bit too long and not allow the adj cup to thrread in far enough. I have not tried this on this bike but that was the way it was when i did my peugeot. I suppose i could try a #5. I dont think i have one laying around though. I think all i have are 3s.

Just for confirmation, my 78 GJ BB is Swiss threaded.

yup. I think that is what im looking it here. Not sure what to do now. Wait and hope i find somthing that will fit i guess.

I believe Phil Wood is the best option for a new replacement. Other than that, you'll have to scour Ebay for an NOS or acceptable used Swiss BB.

If you can't find a suitable spindle to use your present cups, and don't want to spring for an expensive Phil cartridge, you might consider one of the several threadless cartridges available from various vendors, e.g. Velo-Orange, YST, etc.

If you refaced the bb shell and took off a bit of material, might you get enough purchase with the lockring?

how are the YST units? do they work well or are they junk? from what i can tell is they look tapered thus wedging themselves in the bb. I would think this would damage the the bb threads. THe VO one says it expands from the inside out which wont damage the threads but they are about $60. If i could find a #5 spindle id try that again but i cant find that thing to save my life. I could have sworen i had one here somewhere.

The YST units are junk.

That figures. Most of the YST stuff is.

well....im going to try another spindle (italian) and see how that works out. Its either that or hold out for a swiss cup which isnt likely to surface. The VO threadless is a bit out of my price range. I might change my mind in the future as they do make excellent products and all the time and thought im putting into this is probably worth the $60.

im doing the same thing with a Motobecane.
you think the spindle out of this bb set would work?

https://cgi.ebay.com/NOS-Shimano-105-...74099134632572

You could retap to english.I've done it twice now with no problems using old steel cups.

Agreed. But if the OP needs to get the bike on the road, the YST unit will work until something better is available.