Late 60's French 650b Conversion --- Headset Issues ---

[Theo Jacobson]

I picked this bike up on craigslist and have been slowly restoring / rebuilding it. The frame is by "Cycles La Gazelle" which still exists as a shop just outside Paris (website). It's pretty low end, built with hi-ten tubes and stamped dropouts, but I wanted to go through the exercise of building my first 650b rando-ish bike. The only thing about this frame builder I could really find on the internet is this slightly deranged Retrobike thread. 

Here's a photo of the bike when I picked it up:

There were many issues, some of which were immediately obvious and some which I only realized after taking it home:

- The headset was loose, with the locknut barely holding on to the threads due to a VO decaleur taking up too much stack (foreshadowing)

- Rear wheel was not dished, so the previous owner had been riding the bike with the rear wheel angled in the dropouts so the tire would clear near the chainstay bridge

- Rear derailleur extremely bent

- Bolts for the downtube shifters were too long, and pinching the frame 

- Left pedal bent 

Despite this, it seemed like a fun project so I didn't mind too much that the bike was not in a rideable state. I dished the wheel (Grand Bois Papillon rims laced to Campy Nuovo Tipo hubs) and re-aligned the dropouts and rear derailleur.

Despite some damaged threads on the driveside, I was able to pull (using a vintage VAR tool) the Stronglight 49d cranks (1st generation, without the "Marque" opposite "Depose(e)"). Removing the bent chainrings was also tricky, the bolts closest to the crank arm were rounded and I had to carefully remove them with a hacksaw. Through my local shop I got new TA chainrings from Peter White and mounting bolts from VO, and got the pedal threads tapped to English. 

Here's the finished build:

Even though the tubing is nothing fancy, it feels great. I really like the geometry, the fit, and the drivetrain which is at once simple yet versatile (48/30 and 14-24 5-speed). I started with Newbaums and toe cages but swapped for more comfy bar tape and MKS Lambdas (with pins added). 

However... the headset felt funky from the start. Sometimes it would feel smooth, but then halfway into a ride it would start binding in one direction and knocking in the other. It felt a bit sketchy on descents. I went to overhaul it again, and realized it was because the loose bearings were bunching up on one side. 

So I carefully re-greased and installed the headset making sure that the bearings would be properly seated on the races. Then the true problem was revealed --- the steerer tube threads are completely mangled about 15mm down, so I can't adequately tighten the headset. This is only a problem when the bearings are properly seated. Before, the bearings were bunching up so that the headset felt tight, at least for most angles. But with the bearings uniformly distributed, the headset is juust tight enough that it keeps the bearings in place but it knocks like crazy. 

It seems impossible to get the steerer tube rethreaded to the French 25mm x 1" (???) standard. I'm going to try the more modern VO headset to see if the threads engage slightly higher up on the steerer, but otherwise I'll have to find a replacement fork. 

Any ideas? 

[lena...@gmail.com]

Interesting project Theo! And nice work getting through so many challenges.

If you are willing to give up the quill stem look... I wonder if an Innicycle conversion headset will have enough threaded length to engage with the healthy threaded portion of the steerer. If so, perhaps you can file away the damaged threads. Here is an installation video,  innicycle 1" Threaded to 1 1/8" Threadless Conversion Headset Full Installation: www.innicycle.com - YouTube.

All the best,

Lena

[satanas]

It should be possible to replace the steerer (and headset) with normal English threaded ones, though maybe not at a price you might like. Depending on how much damage there is, and where, a different headset and/or a thicker or thinner crown race might help, as might milling a few mm off the head tube. However, I doubt there's any simple, cheap solution. If you had access to frame building tools there would likely be more options, but if you had to pay someone not so much.

Later,

Stephen

[fordb...@gmail.com]

Wonderful bike ! Is that a Svelto rear derailleur or a Jubilee it's hard to see.

For your headset- do you have enough ball bearings in the headset ? How can they "bunch up" ?

It does sound like you would benefit from a proper facing of the head tube.

Would the threads on the steerer benefit from a clean up with a die ?

You could always braze a stub in the top of the steerer and use a stem with no quill.

Keep us posted-

Ford

Ghent, NY

[David Dye]

A threading die for French threads is actually much easier to come by, since it's a normal size 

https://a.co/d/0fjpMgFE

You could likely get it cleaned up well enough with just a thread chasing file.

[Theo Jacobson]

Thanks for the suggestions everyone! 

Lena, thanks for sharing that Innicycle converter, I wasn't aware of it! As you said the question would be whether there are enough good threads. It's possible... 

Stephen, yeah, it seems like most options involve pretty major modifications that I don't really want to invest in. 

Ford, the rear mech is a Huret Luxe 2100T. I think it looks wonderful and it shifts quite nicely! The bearings were `bunching up' due to improper installation technique on my part. Since I don't have a bike stand I installed the top cup facing down, and by the time it felt tight some of the bearings had migrated from their original position. When I load up the cups with bearings sitting next to each other I'm left with space for about 1 extra bearing, which seems pretty standard. However I was wondering, if I used more bearings or larger bearings if that would add just enough stack to make the headset sit tight... 

Huh, I didn't think to just search for M25x1 dies, my impression was they were hard to find! That opens up a path forward! Fingers crossed that the VO headset works. I also have my eye out for replacement forks. Here's one on eBay with the right steerer length, but I don't know how the axle-to-crown of 650a forks compares to 700c. 

-Theo

[Stephen Poole]

If you can source a French threaded die for a tolerable cost - or find someone who has one - you could also try (carefully!) building up the damaged area with brass before chasing the thread.

Best of luck,

Stephen

[Leif Eckstrom]

Hello, great project. Thanks for sharing the challenges and the enthusiasm. I suppose if it doesn’t work out for this particular bike, you’ve worked through most of the problems with these wonderful French frames that you’ll be able to apply to another build should it come to that. I’m glad to learn that cheap dies exist for this application. I hope that works for you. 

One other issue is headset stack height. I see your frame has a stronglight competition or p3 headset. Those have a relatively low stack height, which means you likely have a 33mm to 35mm stack height on your frame and fork. Campagnolo record headsets required 38-40mm of threads. Unfortunately the VO French headset was built to a 38-40mm stack height, maybe even 41. That seems like an unfortunate design oversight since most old, French forks were cut shorter to the stronglight spec. 

One possible way to get some stack height savings and fix a worn headset is to use a lower cup from a low stack and easy to source “modern” headset—say a tange cds model, $30, available with 27.0 or 26.4 crown diameter. You would then use the top section of your existing French -threaded headset to match the treaded portion of your hopefully revived French threads on the fork. 

I’ve been plagued by this French headset and stack height problem before and just recently learned that Zeus headsets were typically French threaded (unless marked “BSC”) and well-regarded by the late great French bike boom historian Chas. Colerich. You might check his posts on bike forums classic and vintage. His handle was “vertyg” I believe. Anyway, most of this info I learned from reading what Chas. wrote. Chas. also indicated the stronglight headset cups with a V-shaped channel in the race (for the loose bearings to run in) never wore out in his experience. He didn’t think Campagnolo headsets were particularly long wearing, and he thought stronglight and Zeus were better headsets for durability. 

Good luck to you! I’m currently working on a 72 or 73 Gitane super coursa frame that came with a Campagnolo headset, and has the higher stack height. 

Best, 

Leif in Chicago

[Stephen Poole]

FWIW, Campag track & GS headsets had both loose balls and a lower stack height than road, IIRC ~33mm, as did Shimano cartridge bearing headsets. Finding either might be challenging though. Milling the head tube shorter can definitely work IME; we used to do this routinely with Cannondale frames in the early 90s so we could fit Stronglight needle bearing headsets.

Later,

Stephen (who's luckily seen very few frames with French threads here in Oz)

[Theo Jacobson]

I'm actually hoping that the increased stack height of the VO headset will work in my favor. If all goes well the VO top cup will set a couple mm higher on the steerer without bottoming out on the bad threads, while not sitting too high as to compromise the available threads for the locknut (yes, it's a fine line...) I was planning to use the flimsy Mafac cable hanger in lieu of the lock washer, but if I need the extra space I'll swap it out for a stem-mounted one that sits above the headset. 

The steerer is quite badly damaged so I do worry about there not being enough material to cut/chase good threads. I don't own a bike stand let alone brazing equipment, haha. 

-Theo

[Brad]

I second Stephen's suggestion.   Almost all of my restoration/ conversions have involved replacing the fork with an ISO threaded model.   It solves so many problems.  

[Brad]

Crust has two flavors of threaded forks on offer.  SOMA has some iterations of the Champs Elysees fork that should work.  Scrounging around on eBay may bear fruit.

[daxo potato]

i too have an old French project bike, with headset problems. it rides like a dream even with similar stamped dropouts and not particularly light tubing. what is it about those French bikes?

my issue was the headset loosened up on a ride and i didn't notice it until it had ground a divot in the steerer. I've concluded that fork replacement is probably the way to go. the problem is the bike is fully chromed with a fantastic orange clearcoat. replacing the steerer will probably cost similar to a new fork and destroy the paint job anyway, so maybe that black crust fork will be ok.... 

here's a picture. found a NOS TA track crank after folding over the solida ring on the cottered cranks, and got rid of all the danglers and what not. 650b wheels built by Anthony at longleaf. yes, I'm aware that it needs brakes as well as a new fork. 

cheers

Dave in NY 

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[daxo potato]

not sure why didn't attach first time...

Dave in NY 

[Ken Freeman]

Ken Freeman
Ann Arbor, MI USA

A few:

I think French frames, or maybe just frames from small builders, can be irregular, and the existing head and fork bearing parts should be carefully disassembled, cleaned and measured, with all associated spacers included.  Need to see if you can infer what the original dimensions are, carefully looking and counting with a magnifier.  We should try to observe the suspected trouble spots, like the area 15 mm down, to see if any damage can be recognized.

Not sure I’ve seen thread saving files et pointmentioned as a tool to smooth rough bearings.  I bought a set from Granger and used them on the original HS bearing parts f sfor my 1952 Rudge Aero Special.  The bearings re finally all in decent, smooth condition that will allow the frame to be assembled with good alignment and freedom from binding - can’t wait to have her on the road!

Another point:  I would work hard (well, I did!) to correct any alignment deviations  on the original old fork.  I did not maintain this care in getting the front end of my Mondonico restored after a terrible front end

crash with header.  Bike was converted from a wonderful Mondonico long stage race. geometry to what I see as a too quick crit geometry, after I shared my own geo measurements with him!!

There are too many variables in fork/frame matching.  If you like the way the ancient one rides and handles, it might be hard to get a modern builder to match the feel of your old setup, which you clearly love!

ader

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[Theo Jacobson]

The VO headset swap was a success! The VO headset has a more modern design that looks like a `dome' built around caged bearings, compared to the older, flatter one. As a result the threads of the VO top cup engage much higher up on the steerer, despite a < 1mm increase in stack. Here's a cartoon:

Due to laziness, lack of proper tools, and stack height worries, I just swapped the top half of the headset. I reused the mafac cable hanger and original locknut. 

Everything feels nice and solid and smooth. On the other hand, this process gave me another chance to take a look at the damage to the steerer tube, and it's pretty bad:

Maybe some of you wouldn't continue riding a fork in this state. Absolute worst case scenario would be the steerer snaps in two while riding. But because the stem expander plug is `holding on' well below the compromised point, this scenario seems unlikely to result in a loss of steering. In any case I'll stop riding this bike on fire road descents :) 

Thanks for all your input, 

Theo 

[Stephen Poole]

If it was me, I'd pull the fork out occasionally and check for cracks at or near the bottom of that trench...

Later,

Stephen