Retrogrouch731

I was gifted this frameset and have spent hours trying to figure out what it is and have yet to come to a confident conclusion. It is Reynolds 531(has remnants of the French language decals on the frame and fork), Campagnolo dropouts on the frame and fork, and the bottom bracket and fork are English threaded. The frame tubes are all pinned inside at the bottom bracket junction. Overall fit and finish is above average.

edit: the bottom bracket and fork are French threaded.

Retrogrouch731

Also I’ve weighed the frame and it’s about 4.4lbs.

juvela

-----

thank you for this inquiry

fine job with the pictures

this lug pattern produced bty NERVEX for Motobecane and is proprietary to them

if cycle a U.S. market example it would likely be the Grand Record model

suspect it may be a Euro model which would have a different model name

appears to be mid-1960's era

here is an image of this lug pattern on a 1973 model Motobecane Grand Record



-----

Retrogrouch731

I’ve suspected it may likely be a Motobecane but have yet to find one with the same stye of finish at the dropouts on both the fork and frame. This frame has a distinct scalloped finish on the ends of the stays and fork blades that no Motobecane I can find has.

juvela

-----

this question of the detail of the ends finish of the taper tubes came up recently in another forum thread

it was clarified by member verktyg IIRC

if you search under his name and taper tube detail you may be able to bring it up...

also conceivable the cycle could have been badged as Motoconfort

IIRC the Monfor badge had already been discontinued by the time of its manufacture...

MB owned several of these less well known names

---

the mounting hole for the rear caliper brake in the brake bridge appears it may be another MB feature. it looks in the photo that it may be larger in diameter than required to accommodate a 6.0mm mounting bolt. on some MB products the hole is larger than standard as a ferrule is employed. these are fabricated of stamped steel sheet and are plated with a satin finish. if lost they can present a snag for an assembler. note that the bridge appears to lack internal reinforcement; this is also consistent with employment of the ferrule.

-----

juvela

-----

​​​​​​https://www.bikeforums.net/classic-v...ification.html


-----

Retrogrouch731

Thank you for the help and link to that other thread. It appears I have a higher end Motobecane of some sort based on the fish mouth dropouts. I assume it’s an uncommon European model as there is no other like it photographed and posted here in the states that I can find. This information has been immensely helpful and fills in a lot of blanks that will further help me research and conclude what it is. I plan on building it up as a winter project later this year into next.

juvela

-----

the two things which make me suspect it to be a European model are the livery and the crown

have never seen an MB produced cycle in the U.S., regardless of how badged, exhibiting either this livery or crown

ironically, Mercier employed this colour scheme widely for a fairly long period. not suggesting any Mercier connection.

​​​​​​https://www.bikeforums.net/classic-v...ch-market.html


-----

repechage

Screams French to me. But of english threading...
You verify the fork steerer threading and quill diameter?

zukahn1 

Moto based on lugs as said as for the threading bb width they started switching to ISO JIS on some models to allow for Japan and other none French componet,s to save costs as early as 1976 when the company was in a bad way finance wise. So everything seems to fit match a mid level Euro model Motobecane circa 76-78.

MauriceMoss

Nice frame you got there Retrogrouch731, and a rare-ish bird, too.


The fork crown, light blue paint (including the lining & pinstriping and the contrasting lug color), seat stay caps and the serial number stamped at an angle on the rear NDS dropout are all consistent with Jeunet.


I have four examples of Jeunets built with those lugs, as well as one Jacques Anquetil (which I assume is a Jeunet-built (since they split production of JA labeled frames with Cizeron at the time)). There were also two unmarked frames built using those lugs posted on BF a while back that I think are Jeunets, too. It would seem that (at least with their 630 models) Jeunet was pretty consistent in the use of that fork crown but there were at least 3 different types of lugs used over the years.


I'm not aware of any connection between Motobecane and Jeunet - as far as I know they were two different companies, in two different towns, going about their two different businesses.
I've also not come across any official documentation stating that these Nervex lugs were exclusive to Motobecane; it's just that they appear almost exclusively on Motobecanes (apart from very few Jeunets). This would be an interesting bit to dig into deeper and find out. I too thought for a long time that these lugs were special to Motobecanes - the first time I saw a Jeunet with those I thought it had to be a rebadged Moto.


As for the rareness of this frame, I don't know if the use of these specific Nervex lugs on Jeunets was done for just a short period of time or what, but you don't see very many of them around. Having Campagnolo dropouts makes this one even more rare since there was only one Jeunet model made with those dropouts - the 640.


The British threading is a bit puzzling, as I don't think I've seen any Jeunets with BSC threading (or at least not stated in threads about them).


Anyways, on to the pics.

Apart from the color, I think this is the best match for the mystery frame:







Seat stay caps, lined around the edges and sometimes down the middle, too (that 'tail' going down the stay was very fragile as it seems like it rubbed off on most frames):






Here are some serial numbers (apologies for crappy pics; it's all I could find):





And the other 3 Nervex-lugged Jeunets:

zukahn1 

Great detective work MauriceMoss the Jeunet 650 pro is such rare bike that the rest of us here didn't even consider it about the nicest and rarest of the French bikes from the bike boom era.

Retrogrouch731

The inside fork steerer measures 22.2mm with my calipers and a test fit with a Cinelli stem confirms this(tight fit). I was wrong about the English threaded bottom bracket, it’s French threaded. I have only dealt with English and Italian threaded bottom brackets before and hastily partially threaded in an English non drive side cup and concluded it was English. I went back and confirmed the drive side is indeed right hand threaded as well meaning it’s French. The fork steerer also appears to be French as an ISO headset threads on but is quite loose(I don’t own any French threaded components). I received this frame last month and since it’s the warm riding season now, most of my energy is put towards riding and projects like this wait for the winter when there is a surplus of time and energy. Thanks to all for the responses and feedback.


here is a clear photo of the serial number

zukahn1 

The sizing threading was done none French to allow for the the top end Campy and other none French top end components of the time. This is a nice detail that makes these one of the more sought after 70's frames. Based on the few Jeunet's I have worked on and the 620 I still have the steerer is actually 22.1 or so works fine with French stem and while a tight tight fit most ISO 22.2 stems will work.

Retrogrouch731

I just found this listing for this exact frame. This isn't just a similar frame, it is the exact one in my possession: the size, scratches and marks are a perfect match. This was listed in 2013 in Massachusetts. I got this frame from a friend who got it from a shop outside of Cincinnati last fall (2020). No details are given in this listing to what model it might be.

juvela

-----

thank you so much for this additional information gents!

now all lines right up


-----

zukahn1 

If it has Campy drops it's a 650b . The 600 seems to stand for nothing the 50 stands for it is the highest of five models and the B seems to indicate robins egg blue paint not completly sure on this.

Retrogrouch731

The dropouts are perfectly aligned as I got this frame. Not sure if a previous owner or a shop tweaked them. I have fallen in love with this frame after learning what it is and more about French frames from this era. This frame has lots of nice details(lug thinning) and is quite cleanly done compared to most of the French frames I’ve seen. It has a few spots with some extra brazing material around the back of the seatlug but hardly anything that is too noticeable nor makes the frame seem sloppy. There are no notable gaps in the brazing around any of the lugs, something I still see on some significantly more prestigious frames and isn’t that big of a deal anyways as they usually are small and not very deep. Overall, it’s a very well made frame. I’m likely going to build it up using parts I already have (Campagnolo nuovo record and a 1st gen dura ace crankset that’s not going to be used otherwise as I don’t have anything built up with that group). I will likely get the French threaded bottom bracket and headset from Velo Orange.

zukahn1 

Final alignment was considered shop assembly work on this era French and most road bikes. Some shops did it nicely while others didn't bother it is great that this one is aligned and you don't need to go through hassle of aligning the frame and fork. It seems two thirds off the vintage road frames I come across need alignment work. I do also like the lug work on the Jeunet's which is nicely high lighted by the gold pin stripping on the black lugs.