I'm guessing this isn't repairable... :(
 

I've been slowly working on this Motobecane Grand Jubilé.
I needed to move the front derailleur down because I bought some new chainrings. It came to me with 52/42 rings and now has 47/32 rings. I decided I might as well clean it up as long as I had to remove it. Gave it an ultrasound bath and then a bit more spot touch-up with a bit of degreaser.

As I'm working on it in my hand, the hinge breaks. I knew these things were fragile, but dang...

https://live.staticflickr.com/65535/...2606d61b_c.jpg
https://live.staticflickr.com/65535/...87649602_c.jpg

Maybe with some JB Weld. A stroll through Ebay might turn p piece though

Looks like there was a casting flaw or the hinge wing had been previously damaged from an overtightened bolt. They're fragile but shouldn't fall apart just from you looking at it too hard. Toast as far as I know, I'm afraid.

Simplex SLJ? If so, not uncommon at all.

-Kurt

Good guess. :thumb:
Huret Jubille derailleurs were light and as fragile as that were "pretty"with the front derail famous for flexy indifferent/balky shifting and a vague indifferent rear derail.
That one's Done, surprising it lasted this long.
Find an old ST or Shimano front for cheap or a Campag for not, ditch the long-throw Huret DT controls for ST ratchet type and get on with it, all will work better.

That being said, once sorted you have one of the best riding club frames of the era. Light, compliant on rough surfaces and predictable on descents they were highly sought after by Century club riders "back when" and often fitted out w/ TA triples, ST V-GT Luxe rear derail, Fr ST and ST barcons to get up and over challenging terrain at pace.

Smart owners stripped the Huret components off straight out of the box and sold them to the "weight weenies" of the era, who like "weight weenies" of all eras spent $ and rode little, took those $, did the conversion described above and Proceeded.

-Bandera

I had a Campy break like that - made me sad.

I've run a Jubilee FD once. You nailed it's characteristics - a banana peel would probably shift crisper.

I'm not convinced of the RD's performance though; they're not much better or worse than a Nuovo Record. I've taken to pairing the RDs with Cyclone M-II/Superbe infinite band FDs, probably up there with the best front derailers of all time for classic 53/42 combos. They don't always look like they match, but they disappear nicely into the build.

The clamp-ons work just as well too, and are much easier to remove when in rough shape.

https://cimg0.ibsrv.net/gimg/bikefor...1dd41174ea.jpg


-Kurt

Yes, if it is a Simplex LJ or SLJ FD, it is a common problem.
The clamp body and strap has sharp corners at their edges where cracks can start when the anchor strap is overtightened. One area where they usually crack too, is at the narrow actuating arm slot corners at the bottom of the clamp body. Ran across a couple of those already from sellers at eBay where they either did not noticed the cracks before they sold it to me or just did not think they were a problem. Fortunately I was able to return them and get a refund.

Bummer. Might be repairable only if extreme measures are taken. Like TIG a blob right on there and file/grind/drill it as needed to match the original. If you have access to a TIG. Wouldn't do that to a crank, but it should be enough for a strap. Another more extreme solution would be to disassemble and get that piece 3d scanned, then get a new piece 3d printed - or CNCd. The problem area could be beefed up slightly. It would take a lot of work to make that happen, since it's the main casting of the derailleur.

Sensible approach would be to glue it back together with JB Weld --and then put in in a decorative case so that the beauty of the design can be admired in perpetuity. They worked OK when well set up, as I recall. But that one has done its duty.

Should have made 'em out of Delrin... :lol:

I really like the lighting in that photo. Well done.

Not to mention the excellent depth of field!

Right?!

Wish I could take pictures like that.

3D printing another aluminum band isn't necessarily unreasonable (though not worth it for a basic Jubilee front mech) it's getting another roll pin installed without wrecking the tab that I'd be worried about.

It's something that'd be an option for a hugely unusual part.

You're all too kind - but the reality of it was that I must have taken that photo about 100 times, using slightly different framing, f-stops, focal lengths, and whatnot (swapped lenses twice). I still don't think any of them came out just the way I wanted.

I was getting so ticked off with the height of the grass (note that I found a bare patch) that I almost contemplated bringing a lawn mower to the park :lol:

-Kurt

JB weld won't fix it, and TIG weld a tiny piece of aluminum? Yeah, right.

Just replace that derailleur.

PM sent.

Thanks for the responses. I imagine it was probably already cracked when I removed it and that it had only maintained its integrity out of habit. Replacements aren't unobtainium (looks like $70-$100 on eBay), but what are the odds the one I purchase is already cracked? Or that it cracks while installing it?

I grabbed a SunTour Vx from the bin, so I can keep moving forward. Kind of a shame though, as the bike was completely original. I will take a look though. Perhaps I can graft the Huret cage onto the SunTour body.

https://live.staticflickr.com/65535/...a342f735_c.jpg

Probably cracked before you put it on - I've been able to confirm some of those failures with pre-build photos.

You're better off with the Vx. The Jubilee shifts like crap and won't look good over the small chainrings anyway. Don't try melding the two, it isn't worth it.

-Kurt

The FD clamp is not the right diameter for that bike.

Here is an old thread with some useful info on how to get that FD to work right on that bike. Threads like this really ought to be in a special C&V folder (a kind of a sticky).

https://www.bikeforums.net/classic-v...amp-shims.html

Ditto. Methinks there's a vignette involved? :thumb:

Do a poor man's magna flux test on the clamping band. Spray it with some WD-40, not to much, just get it oily and let it soak in good. Lightly wipe the surface clean, and then sprinkle some baby powder over the surfaces, let it sit for a short period then wipe gently again. Any existing crack will show up as easily visible white line outlining the crack, it one is present. Use good direct lighting so that even a slight crack holding the oil/powder shows up.

Used this on motorcycle parts (MX and XC racing,) an NDT lab tech taught it to me, he did the real thing regularly on metal parts and fabrications.

Bill

Clearly I wasn't clear. It is not practical in any way to repair that derailleur. I agree, just replace it. I was just saying that if cost is no object, it's technically possible.

The JB weld was only suggested to hold it together enough to sit on a shelf somewhere. High strength epoxies are roughly comparable to lead/tin solder in tensile strength (if properly applied), which is not enough in this case.

I would trust a 3d printed piece even less than the original, and it's not like it would be ready to use out of the machine. It would require a lot of precise machining. Probably easier to just mill the thing from a block.

I maintain that TIG is possible, but not in the way you're all probably thinking. Actually, it's even technically possible to weld the original pieces back together with specialist gear. Micro welding is a thing. Probably cost (as a WAG) 50x the value of the derailleur to have it done.

No doubt. I didn't have a known French diameter front derailleur, and the Vx clamp doesn't come close to bottoming out. Also, it didn't show any gaps between the clamp and the seat tube. I think it should be good until I can find a proper replacement or construct a shim.

Good idea, but if I was to (for instance), find a suitable candidate on eBay, I'd have to purchase it, test it, then quite possibly ask for a refund. That would be kind of a PITA. Even if it passed that smoke test, I might break it during installation, no matter how careful I was.

I'm not at home right now, but when I get a chance, I'll take a comparison photo of the Huret derailleur and just about any other in my parts bin. It's a beautiful piece of artwork, but looking at the hinge, it seems clear no mechanical engineer was involved in the design. Not even a seat-of-the-pants engineer.

Hi, Skip! I had the same failure occur on a Jubilee. If you are interested I could dig out my fragments and you can see if you can try to piece it back together. Perhaps the failure on mine complemented the failure on yours?

Also, there were a number of other Huret front mechs. I have one that I have used on my 2 x 7 friction system on my Trek 610. I don't want to sell it, but I will look for it on Velobase and see if I can find it. In the past I have not found it. That one shifts a 52/39 VERY well and has not broken after about 15 years in place on that frame.

@Salamandrine @gugie The size of the clamp is not the issue for TIG welding. But the alloy is. A lot of aluminum alloys used for forging from that time period are not weldable.