Here's an underslung demultiplicator modification, that I've executed for a vintage tandem project's speed config. I'm always interested in C&V creativity, but haven't stumbled across any particular thread yet... C'mon folks, blow my hair back with your contraptions & contrivances!

This is a project that is intended for next winter. I've mentioned it a few times and it's coming along slowly, mostly because I am a tightwad and don't want to throw lots of money at it.
craigslist find Peugeot UO14:


I have a Sturmey-Archer AW 3 speed hub. Using a technique published by Sheldon Brown, I am planning to install 2 modified Shimano cassette cogs on the hub (14/24), and 2 chainrings on a touring crankset (38/28) which will give me 2 "ranges", high and low, with 3 speeds in the hub to make 6 speeds. The two ranges both wrap 52 teeth, so chain tension will be no problem. I think I will use wing nuts on the rear hub to allow easy shifting. The chain will have to be hand-shifted, which is fine because the point is to have no derailleurs for a clean look and no icing in the winter. I also have MAFAC Racer brakes and some "Randnner" bars. I just need a dark ano Matrix rim to build the rear wheel.

Shimano 105 BB with gossamer cranks... but most important the rack is attached to the rear triangle with a couple of insulated electrical connectors which add strength, stability, and because of the rubber coating won't damage the paint.

I can appreciate the handtossed gearing on the right bike, and I love a smooth connection... That Bell's pivot facilitates shifting accuracy betwixt a Frenched retrofriction bar lever & a long cage rear gear. It will allow for a smooth overall transition between narrow gears & route wiring with the top stop eye.

Uh, would you please explain what a underslung demultiplicator modification is, and how it works?

In this photo you can see the home-made bar end shift lever on my 40's Fothergill:

The lever is held by a heavily modified Suntour bar end shifter body, which had been broken previously.

In the same photo you can see a handlebar bag that is also home made, custom tailored, etc.

You can also see the 1930's (?) Centralpull brake, for which I had to fabricate part of the clamp that holds it to the fork. The part that isn't rusty, that's the part I made.

The shifter, shown above, operates a Resilion derailleur that shifts the chain between two cogs on a Sturmey Archer dyno-4-four hub.

Of course the derailleur isn't home-made.

You can't really see it in the photo, but the tail light is attached to a home-made bracket. There's a similar bracket on the fork.

Let's see:

Homemade light bracket:




Another homemade light bracket:


Battery LED retrofit of a 1950s Soubitez taillight:


Dynamo LED retrofit of a 1950s Soubitez taillight:


Dynamo wiring conduit through the chainstay bridge:




Nokia cell phone car charger cord, re-purposed:


Rack bracket flush-mounted in brake spacer:


Blinkie light bracket, re-purposed as a fender mount:

"Would you please explain what a underslung demultiplicator modification is, and how it works? "


Demultiplier (Démultiplicateur in French)
A bell-crank-like device formerly marketed by Simplex as an accessory to their bar end shifters. It attached to the seat tube just above the bottom bracket. It served the function of a cable guide, but had two separate cables attached to it. The cables attached to a pivoting part at different radii, so the mechanical advantage was altered by this unit. This made it possible to shift reasonably well with the barend shifters, even though there was a stone-age Simplex derailer at the other end.
The cable from the shifter connects to point "1", acting on radius "A".
The cable to the derailer connects to point "2" acting on radius "B".
the cable travel at the upper section is increased by the ratio A/B. Cable tension on the segment between the shifter and the demultiplier is reduced by the ratio B/A.


Well this essentially explains the demultiplicator's form & function. I've just had to route mine underneath the tandem, rather than alongside the bottom of the seat tube. I'll be needing it for all the length between the rear gears and a Simplex retrofriction bar end lever. It's an overcomplicated bit of brand collaboration, but I've had fun cobbling this parts bin puzzler together.

Love that Fothergill! I've seen a grand ol' wooden-knobbed bar end lever that would look right at home on it. Are those shallow Lauterwasser/Highgate bars or inverted North Roads?
I've also been wanting to upgrade some Luxor Le Martele lights with LED, I'm sure I'll have some questions.
That brake arm light bracket is an elegant solution, looks the right part. Sure wish my touring tandem had the internal wiring option... I'm a fan of that useful little rear mudguard fastening, and the repurposed phone cord!

Thanks! A wooden-knobbed bar end lever sounds interesting. I don't suppose you have pics? The bar is the new "Lauterwasser" bar from Soma. Not to be confused with a real Lauterwasser, but the best I could do.
Stop right there! This thread is about DIY and modifying what's already there, right? The solution, obviously, is in your hands. You won't be the first.... In fact, I am strongly tempted to drill my Fothergill frame for internal wiring, though I hesitate to modify a frame this old.

Very nice mods! I am taking notes for future builds. Now I'm inspired to use some of those turkey legs I've pulled off old bikes.

Side note: sorry rhm I couldn't resist a take on your avatar when I was out taking photos the other day.

Can't seem to locate any snaps of an early barend example, at the moment. Won't be drilling, but you've a valid point... Them Jack Taylor Super Tourist single/double frames had a proprietary Reynolds 531 wiring tube fitted. My next project will have to be fantastically complicated.

I like it, what're you apologizing for, at least you made yours yourself! I stole mine from Picasso. Hmm... maybe it's time for a new avatar....

Ditto - I particularly like the fender mount from an old blinky-light bracket, and the brake-caliper light mount.

I was reluctant, but after speaking with some frame builders, was convinced it's not a problem. However, I would not drill a main tube myself, because it should have a welded or brazed reinforcement-- which I'm not capable of doing myself. The hole on the downtube near the headtube lug has a brazed-on reinforcement: a 5mm bottle cage boss with the threads drilled out. The only other hole drilled is at the bottom of the bottom bracket shell; this has no significant impact on the structural integrity of the frame. Some BB shells have huge sections cut out for weight savings. Everywhere else on the bike, pre-existing opportunities for internal wiring were exploited. The existing fork and fork crown vent holes were utilized for running the wire inside the fork (which was no small feat), and the chainstay bridge hole took a 6mm threaded adjuster barrel without modification.

Rudi, I love that bar-end shifter you made! Does the cable path around the lever align closely with the cable stop built in to the mount? What was the lever from originally?

Love it - Great shots and ideas - THANKS

Thanks! It's not as functional as a Suntour but style is everything.

I'd been looking or a suitable chunk of aluminum for this purpose for a while when, on my morning ride up 8th Ave on my way to work, I found a pedal and half of a crank arm. And when Providence offers me a piece of cheese, I take what she offers. I had to fill a groove in the back of the crank arm with JBweld; you can see a hint of that --it appears as a dark gray shadow-- in the photo. Then I hacksawed, drilled, filed, sanded and polished the present shape out of the raw material of the crank arm. The lever itself is pretty primitive. I cut the cable path with a hack saw, which lines up with a two-step drill hole for the cable head. It lines up with the cable stop in the shifter body just fine, but my design does put a kink in the cable near the cable head; I suspect this will cause fatigue and premature failure. I first used this shifter for switching between wide and medium on a Sturmey Archer S5 hub, for which this was pretty successful. Now I've switched it to the Resilion derailleur, which has a very strong spring, and this shifter doesn't hold it quite well enough. I'll probably be able to fix that with suitable washers....

Nice. I thought I was slick with filing that brake arm, but your filing handiwork takes the cake.

Thanks! By the way, my new avatar is a violin head I carved out of cherry for a half sized violin. I started working on it when my son graduated from 1/8 size to 1/4 size fiddle, and stopped working on it when he graduated from a 3/4 to a full sized one. Big project.

This is a version of what I was describing, with a cast-knob end. They were produced by Cyclo, and I find them on EbayFr occasionally under the title passe-vitesse.

Mmmmm, that's what I've been looking for! I'll have to add passe-vitesse to my searches.

Geez, Rudi. Color me impressed.

No, you can be impressed if I ever finish the project. Meanwhile it's just a nicknack I've invested too much in to throw out.

I just finished some extensive modifications to BF member Henry III's Schwinn Sports Tourer:

https://www.bikeforums.net/showthread...rer?highlight=

Wow, that was you behind all that transformation? Impressive! Totally jealous.

I saw this simplex shifter retro friction lever which opperated the dynamo while on a little randonneur event



whole bike photo here