I received a free (probably 1971) UO8 that will take a lot of work. It has badly rusted cottered cranks. I suspect the BB threads may be French. Would it be possible to replace the spindle and convert to a 3 piece crankset?

Sure.

Just do a search on that topic in the forum, there is plenty of info on how to do it.

I have what's probably the same bike. The BB threads are definitely French. Right now I have the BB spindle from my Shimano 600 (6207 model) chainset running in the original French BB cups. The cranks are the Shimano 600 double that goes with the spindle. It works fine, so far, and took pounds off of the bike.

I think there is a way to use your current cups with a square taper spindle. the french/Peugeot experts will tel us more shortly

I converted my U08 ('72 unless I totally misremembered when I bought it) to a Sugino cotterless crank with Sugino cups. Later I restored the original cottered crank with the original cups but I am about to do a conversion back to cotterless with those cups. I see no reason it shouldn't work. (On the other hand, it isn't clear whether either of the two spindles I have to use will work.)

As everyone has said here already, it's absolutely doable - simply stick a suitable (i.e., thin cup spindle for thin cups or thick cup spindle for thick cups) English 68mm square-taper spindle in place of the French spindle.

In fact, there's nothing unusual about this swap. The folks who started the French thread myths seem to have further propagated the (incorrect) theory that French cup-and-spindle BB's are somehow remarkably different from any other, and therefore impossible to maintain or modify.

-Kurt

wow, that's good news for me too. I've got a pug in the queue that's gonna get the same treatment. thanks.

No problem - Just did that last week on a UO-8 - You will need at least a 5s-B 70mm crank spindle Bottom Bracket Axle 5s-b Road 70mm (35-54-37.5) 126.5 Bolt Type (Italian OK) - Must use loose balls - Remember to put the longer side away from the crank side for more room to play on tightening the cups - Heres a link if it will post cause finding the 5s-B is getting increasingly hard...

https://www.amazon.com/gp/product/B00...ef=oss_product

Also - Are you going to braze or silver solder on any extra bosses or convert over the dérailleur drop out and shifters... Sounds like fun... fun... funn... I love old Pugs...

https://www.bikeforums.net/showthread...4#post10902984

70mm? Did you use a 70mm spindle designed for thick cups paired with French thin-cups in a 68mm shell?

^
To the OP: Do not pay any attention to that.

-Kurt

cudak888 - Yes I guess I did - But I am always worried I am doing things wrong - I had to go to the 70mm 5s-B because a normal 68mm did not give me enough room to fit the cups and get the tapered crank on right - I really don't know if they were thin, thick or French, but they did thread on and tighten so I considered myself lucky - This method seams to work with thin or thick cups as long as you are using loose balls - Hope I am not wrong in doing this... Allot of times I am just putting things together from left overs...

I have been contemplating this move as well:

Sheldon has the following:
"
French bottom bracket cups usually have thinner walls than Japanese ones, so the bearing ridges on the spindles are farther apart. If you use a standard Japanese spindle, the adjustable cup won't be able to screw in far enough to snug up the bearings, or if it does, it will sink into the bottom bracket shell so that you won't be able to install the lockring.



The good news is that a Japanese spindle made for an Italian size (70 mm) bottom bracket will usually fit! In the Sugino marking system, these are the spindles that are marked with a "5" code. Spindles for 68 mm bbs have codes beginning with 3. This trick often makes it possible to upgrade an older bike from cottered to cotterless cranks at a reasonable cost."

That reads as if Sheldon didn't want to explain the simple fact that like-threaded cups often come in thick-cup or thin-cup forms. There is no reason to single out thin French cups as being singular or unique, for you'll find thin-cup English and Italian BB's, of which the former BB's spindles will interchange with thin-cup French BB cups.

-Kurt

How do you tell if you have thin cup or thick cup? Where would one measure? Would caged bearings work or is it best to go with loose bearings?

scozim - I just went out in the garage looking for thick v/s thin cups - No luck in any real measurement BUT the cups made for the "caged bearings" were thinner in external width and did appear lighter in weight??? - cudak888 and Sheldon have it right - And I seem to have stumbled onto the right spindle when using the 70mm 5s-B on three cottered crank conversions using loose balls... Ya know... following these threads instead of going out and facing a cold ride is not so bad... But still... My old Fuji (Horse) is calling...

Where are you getting the idea that there are cups made for loose bearings that are different from cups made for caged bearings?

I come back from my garage (where it is freezing....) I have done measurements on two sets of fix cups (french thread).
On the thin one, the thickness of the wall is 1,5mm
On the thick one, the thickness of the wall is 4mm.
My measurements are not very accurate .
Hope it helps.
Hush

I'm not sure how to distinguish between thick cups and thin cups, except in Campy. What I would suggest with the Peugs is simply to get a spindle that is close to what the crank needs (and I happened to have an English -sized spindle), 9 1/4 inch balls per side, and try it. If it adjusts, turns well, and the Q is balanced and acceptable with no scraping of the arms on the frame, it IS good, regardless of the thick/thin rules.

What is the 5s-B spindle? Who makes it, and what is it for? It is NOT a requirement for a successful installation.

Trial and error is fine is you happen to a have a bunch of spindles to choose from. It doesn't work so well if you have to buy them before you try them.

Make that 11 balls per side.

I didn't read this entire thread but if you are willing to drop $50, you can buy one of these and be done with it.
https://store.velo-orange.com/index.p...y-cups-26.html

I had a U08 and was gonna do the JIS spindle with the existing cups or whatever sheldon said. In the end I hosed it down with WD40 and rode it as is.

Road Fan and Grand bois - I had difficulty with a bearing cage on a thick cup once - It may not have been the cup but after that I just went to loose balls all the time - The deal on the 5s-B is just something I hit on when making transitions form cottered cranks on French bikes - Its not "The Way" its just "A Way" to do it for a few bucks... It all seems to work but maybe I have been just lucky - All in all it was very nice to get away from the cottered crank and allowed a greater variety of cranks to be used... Its all been allot of fun... And none of them have failed...

Ok, well maybe I was lucky.

I'm cool with the 9-balls, too. And I prefer loose balls in BBs rather than cages - in an install like this it removes a constraint, that the cage has to fit between the spindle and the cup.

Ok, Zand, that's all cool, and I'm glad for you that something worked pretty quickly. But what IS a 5s-B? What company makes them? Are they in Sutherland's or some other handbook?

My other thought if my Shimano hadn't worked was to measure the old Peug spindle and try to match it up in Sutherland's to a close-matching cotterless spindle.

My main point was that he might just hit it close by luck.