timdaw

Many thanks for the useful suggestions for the FD. I've already experimented with the heat sink material on a wreck frame and it works much better than wet rags, so should save as much paint as possible. I'll give your suggestions very serious consideration. Your offer of details on the FD is very helpful, thank you, i'd really appreciate it!
I just published a blog post on my similar tandem. I got the date wrong in my previous comment here. Jan thinks 1944/5, with modifications in 1947/8.
https://vintagebicycle.wordpress.com...tandem-c-1944/
And here is the stoker stem on mine, for reference. The stem is fillet brazed to the saddle clamp. It's very nicely done, and it has a Herse alloy clamp bolt so I'm inclined to think it's original:

I like your comments about the learning process...."like a virus"!

scarlson 

No problem. Herse information should be free and accessible to the public. I don't understand why, I've asked several people for dimensions between Nivex rear derailleur pivots, and nobody will even respond. I'm not snooty like that. It doesn't cost me anything to measure my bike, and I'm not making any money or friends by keeping secrets. Let me know if you need any further measurements.
First off, mine is a 28/48 double, so all distances are going to be different if the chainrings are different sizes.
The square sleeve-tube brazed to the frame is a piece of 10mm square tubing, with 1.5mm thick walls, for an inner dimension of 7mm square.
The derailleur cage is made of 2mm thick steel, and it is brazed to a 7mm square tube with wall thickness of 1mm.
The tube is brazed to the frame 129mm from the center of the front eccentric shell to the center of the square tube.
The cage is 9.5mm wide on the inside.
The outer cage plate measures approximately 27mm wide x 26mm high at the rear, tapering down to 20mm high at the front.
The inner plate measures approximately 61mm at its widest at the top, tapering down to 14mm at the bottom, and 72mm high at the back tapering to 12mm at the front, following a 98mm radius centered at the center of the eccentric.
The lever hole in the derailleur push tube is 10.5mm x 4.5mm. The derailleur push tube is 67mm long in total. The edge of the hole in the push tube is 46mm from the outer cage plate.
The lever hole in the sleeve tube which is brazed to the frame is 19.5mm x 4.5mm. The sleeve tube brazed to the frame is 52mm long in total, with the hole's right edge 18mm from the right side.
The distance between the pivot bolt and the sleeve tube brazed to the frame is 38mm center-center.
The pivot stud is 7mm OD and accepts a m5x0.75 bolt. You could use an m5x0.8 and I promise I won't tell anyone.
The lever measures 176mm in total length. The part with rectangular cross-section is 10mm x 4mm and 67mm long, and the part with circular cross-section is 6mm in diameter. The ball end is also 10mm in diameter. I think this was made first on a lathe, starting with a 10mm bar. The bar was turned down to 6mm for the round shaft, but left at 10mm for the ball end and the rectangular end. Then the rectangular end was filed down to become a flat paddle 4mm thick.

Here are some pictures. Calipers in photo are set to 100mm.











Thanks for posting! Interesting to see that the rack on yours is the newer triangulated style, which Jan says was being phased in in 1946.

That stoker stem is very cool, and potentially something I could do just for fun with an old saddle clamp and my torch and some tubing. An interim solution, perhaps. Could you show me a close-up of the brazing in there, so I can see where exactly it was attached?

merziac

scarlson

Almost all my engineering skills are self-taught, or learned by observation. I have very little formal training. Ten years ago, I taught myself to arc weld by borrowing a welder and looking up videos on youtube. If I want to learn a process, that's often where I start. I find they have synergy: you learn one process and it helps you learn two others, like a virus they propagate and take over your brain. On the other hand, I'm nearly always dissatisfied with professionals' explanations of their work, and this alienates me especially given my lack of credentials.

This is the crux of this sort of thing, many times formal training does not prepare you for unknown original out of the box thinking because there was no box.

The original creator caused his vision to become reality because he was skilled and made it happen through synergy and willpower, you have to decide to be the authority on your own to get it done, especially if you want it done your way.

If you are not skilled in a particular skill you may have to try your hand or compromise in some way by a workaround you can live with. This can lead to a completely different fix or resolution, necessity being the mother of invention.

timdaw

Many, many thanks for the pictures and dimensions of the FD on your Herse. I agree with you that information should be public and had I a Nivex derailleur I would have been delighted to provide you with information you needed.
Here is the stoker stem on my tandem. It measures 170mm to centre of the seat post, and is of 22mm tubing. Looks like electric welding rather than braze, beautifully filed, which suggests Herse to me:

scarlson 

Thanks for posting! It looks like an old-fashioned version of the modern ControlTech adjustable stoker stem. I have seen something similar for tandem stokers, made by CoMotion!
Could even be gas welding, who knows! Skillful in any case, given that the base metal is so thin. I could do it with TIG and stainless filler, fairly easily, but filing it down would take forever.

Anyone who's got a Nivex rear, feel free to chime in. I will draw it up in Fusion 360 and put it on Thingiverse so the masses can 3d-print them or cut them out of alu with a coping saw or whatever.

Treasure Cycles

It is me indeed! I haven’t been “active” in that particular Facebook “Treasure Cycles” page in quite a while though...got turned-off by all things “Facebook”.

Treasure Cycles

I also kept away from this forum and didn’t realized (to my pleasant surprise) that it had picked up Again and with some wonderful Posts by not only you but also “timdaw”. It’s great to see friends share all the knowledge we possess without needlessly holding “secrets” back. Speaking of which; I didn’t quite catch the original thought about the need for “Nivex rear derailleur”, but in the spirit of sharing (and feeling part of the brotherhood of vintage quality French bicycle restoration), I’d like to volunteer any and every piece of information I hold and let you know that I currently own a Nivex rear derailleur that still hasn’t been installed onto my Alex Singer tandem, and would be willing to not only take measurements but more than that lend it out to you, my already good friend “Scarlson” so that you (Having the proper engineering skills can take your own measurements In order to share it with others that may want it in order to produce aluminum replicas of the same. I know I would personally love to own one of those! Also, I have a real need for a replica of a stoker stem such as the one our friend posted on here from his Rene Herse tandem in order to replace the smaller, less comfortable Phillipe stem currently on my tandem IF anyone gets to duplicate this.

scarlson 

Oh wow! I would love that!!
The main reason I need to reproduce a Nivex is for my "probably-Dujardin." Someone chopped off the Nivex hanger, and filed the dropout to take a normal axle, but I am going to put it back right. And I will put the plans up for download by anyone who wants them, because that is the right thing to do.

I can probably braze you one. The easiest way to do this would be with off-the-shelf framebuilding parts. Do you want something that looks completely correct, or do you just want something that *works*?

gugie 

Just goes to show you that there's nothing new in bicycles, it's all been done before.

Fixie idjits hacking hangers was done decades ago.

Treasure Cycles

The websites not allowing me to comment until I have 10 posts (most unfortunate). I would love to have a similar stem in your best engineering impression. After all, “beggars cant be choosers“. LOL
Let me know how I can send pics of my Nivex so that you can confirm if it’ll be good enough to duplicate.

Treasure Cycles

Mine is the “clamped-on” to the chainstay instead of the “bolt-on” one. I can”t
picture if this would completely help you figure out How to redo the hacked-off brace, but my offer stands for letting you borrow it.

scarlson 

I will send you a PM with my e-mail address and then you can e-mail me a link or attach photos to an e-mail.
And we'll talk about this stem thing.

Yes, it will definitely help!

Plus ça change, eh?

Treasure Cycles

I see you sent me a private message but the site is STILL restricting me from opening it due to not enough posts. In any case, I don’t mind sharing mine with you here.
It is:
docray@comcast.net
Looking forward to working with you on this and any other “ancien velo” project!

DMNHCAGrandPrix

Great to see this level of detail for rare parts!
Timdaw, I was surprised to see a "skirt spring" spanning the underside of your Ideale saddle. Was THAT a stock item, or perhaps a custom addition by Herse, or other bike owners?

Treasure Cycles

Here are the pics of my Nivex derailleur. Hope they are to everyone’s liking.

ReidH

Hi Treasure Cycles,
Beautiful Nivex derailleur. It is the clamp on version. I had search for a Nivex for my Singer tandem. Now have a short arm converted to a long arm. Also found that the spring tension has to be strong enough to handle the weight of the long drive chain.
Now have the pivots out to be drilled out and bushed. There is too much play from misalignment of the pivot spacing during manufacture. Must of been a bad day at the Nivex shed, I mean factory.

Reid Harding

ReidH

Hi Sam,
If you need some pictures of an unmolested rear Nivex dropout, I have a bike that I can take some pics of. Of interest is the Singer tandem doesn't have rear Nivex dropouts and the Baillieu that has Nivex dropouts has a Cyclo derailleur.

BTW, the Nivex rear axle for regular hubs, not Maxi-CAR is a interesting thing.

Cheers,

Reid

merziac

Paging timdaw

ReidH

One method to reinstate a Rene Herse front derailleur to a tandem that has had it sawn off is to build a clamp on version. There are pictures of an very early Herse tandem in Jan Heine's Rene Herse book of just such a thing. To add to that, I have pictures of just that sort of clamp on derailleur taken off a Herse. Maybe the same derailleur as the pictures. It appears to have many adjustment features that the brazed on versions didn't, which leaves me to believe it was a prototype or designed to be more flexible to changes in chainring size.

The pic's are from Ebay. I wish I won that auction. I need one for my Herse tandem that suffered many desecrations in it's life.

Reid

scarlson 

That's a very cool thing. I love that you can see the machining in it. You can see how on that eye that attaches the cage to the push rod, he started with a round hole and broached it square! Amazing.

Wait, am I going to get roped into building these? I just did one for my Trek, but it was not an exact replica, because when I started building it, I hadn't yet gotten the real thing. It was pretty hard to do, but it shifts well.

ReidH

Hi SCARLSON,

An on demand build would be nice, especially now that you have a actual derailleur on your tandem to work out the important details.

I would buy one as I need one for my Herse Tandem. The clamp on mech allows more fiddling with adjustments to shift better, chainring size changes and the ability to change from two to 3 chainring, if necessary. All without risk of disturbing the soon to be new paint on the tandem.

Reid

wheelman12

Hi. Awesome project. Love these old machines.
I was wondering if you’ve measured the frame geometry? I’m working with a builder on a tandem and would love to incorporate the old geometry...
headtube angle, fork offset, bb heights, wheelbase and distance between the bottom brackets would be really helpful in a comparison to a modern tandem.

seems like the biggest change is in the head tube angle and the bb-bb distance, between the old french ones and the average modern tandem.

thanks!

ReidH

Hi, a Rene Herse tandem geometry can be found in bicycle quarterly 62.
One significant geometry difference from a modern tandem is the low trail found on these classic French tandems.

Reid

jeirvine 

Here it is. That whole issue is worth finding.

scarlson 

Some updates come forth!
I have been let back into the machine shop on a somewhat limited basis. Here's some of what I've done.


Drilled and counterbored clamp bolt holes.


Slit the bar clamp with a slitting saw. I asked for, and got, some training from a career machinist on how to slit properly. He says the problem I encountered last time I was slitting (the screwdriver slot on a Brampton pedal dust cap reproduction) was using slitting saws with too fine of teeth, and ganging them, plus feeding too aggressively for this work (using a mill with a power table so I couldn't easily control by hand). The fine teeth can't handle the chip load under aggressive feeds, so the chips go wherever. This forced aluminum chips between the blades and caused them to bind in the slit.

So this time, I used a coarse saw and was on a different, older mill, and everything went great!

Whenever I'm using a slitting saw, I feel like I'm using this:

And I feel like this will happen, to my face:

Slowly getting over my fear!!

One interesting thing: the original René Herse stem was bored to 25.6mm for the bars and 22.4mm for the steerer tube (yes, it's round - it hasn't just been stretched open during removal of the bars), even though the steerer measures 22.0 and the bars measure 25.0. Mine's made with American tooling, so measures 25.4 and 22.2, and will work somewhat better than the original I'm thinking!
Edit: I will also add that the handlebar clamp bolt holes are 15mm center-center, as opposed to Jan Heine's 17mm Herse decaleurs, and that the original slits appear to have been done by hand with a hacksaw or ganged hacksaw, and maybe some light filing.

I will have to also produce a stoker stem. I will make one of aluminum to be true-to-original, and then maybe also make an adjustable thing of steel brazed to a seat clamp as in @timdaw 's picture. This will give me options for different stokers, one adjustable and one absolutely correct.