Aubergine 

speedevil 

That looks to be a great project. I've been looking around (not too seriously) for a tandem and something like this would be an enjoyable project. It's great that it will have a second lease on life when you're done.

Brian25

Hi, I was admiring your tandem. Do you mind sharing what that green is called or and number code? I have used an old Campy double front derailleur for triples before. They do not work very well for triples. I would recommend a front derailleur designed for triples.

Aubergine 

seedsbelize 

4 cross spokes?

Aubergine 

non-fixie 

One of those exceptional cases in which the repaint is actually a major improvement. Well done!

Looking forward to the rest of the build.

RobbieTunes

That thing is so cool. So fliippin' cool.

Aubergine 

I parked the Tandem in the shed for a few months but got it back out again to finish it off. After working on it a bit the last three days it is close to done. As should be obvious, the timing chain still needs some adjustment, and I think I need a half link to make it all fit. And the crank needs to be spaced a mm or so to the drive side. As it is, the front derailleur can’t pull the chain onto the granny. Otherwise it works pretty well for an old Tandem!

Oh, and the rear drum brake. I set it up as a drag brake. The two Mafac brakes are operated by the normal levers, but I mounted an old Huret stem shift lever and ran a cable from that to the drum. So going downhill, I can put on the drum brake and then modulate speed further with the regular caliper brakes.

A last fun touch is the Campagnolo 980 rear derailleur, to which I added a Soma long cage. It works pretty well!

tiger1964 

Lovely, including the paint and I'm not even a fan of green.

Alas, I think the only Gitane tandem I've ever seen was in the brochure I picked up when I ordered my Grand Sport in 1971.

Every line looks just right.

thumpism 

We had one for a while but didn't ride it much. Fun to play with but it also took up more than its share of space in a crowded basement so we let it go.

due ruote 

Well done, grasshopper!

Will the eccentric bb not take up that slack in the timing chain?

Aubergine 

I was not quite able to connect the chain when it was at its slackest position, and as you see in the pic it is still slack at the tightest position. Of course I might just be a lousy tandem mechanic.

due ruote 

Your timing rings look pretty small. (Or is that an illusion?) With bigger rings I believe you could take up more slack.

Aubergine 

My recollection is that they are 30 teeth. Larger rings would not help take up slack; every one tooth increase in size (times two chainrings) would mean I would have to add two links to the chain, leaving me in exactly the same position I am now.

verktyg 

Nice paint job. The green is close to the color Gitane came out with in 1974 when they switched from foil decals to the yellow or green clear plastic sheet style.

Yours is the "TANDEM SPORT" model.

We kept at least one of those Gitane tandems at the shop until about 1976 when they became unavailable. Most of them had Mafac Cantilever brakes but I've seen them with Mafac Caliper brakes like yours.

Only rode double on one of them for a few short rides but lots of single test rides on new bikes and customer's bike we were working on.

Most of those tandems we worked on were set up with a brake lever for the Atom drum brake on the rear bars. Some folks thought that it gave the stoker something to do or at least the sense of some control.

They used an odd 1 1/8" headset. We tried to grab all we could get when we found them. They may have been British thread??? Also there may have been some Stronglight 1 1/8" headsets used on those tandems.

1969 Flyer, List Price $199.50


1970's Catalog. This picture was probably filmed in Maryland not France.



In 1976 we started bringing in a few Andre Bertin tandems from France.



verktyg

non-fixie 

To me it looks as if it is not yet in its furthest forward position. Try getting it further out. If that doesn't remove the slack, then winding it fully back and removing a link should do it.

Oh, and you might want to synchronize the cranks a bit more for peace of mind.

Love this green color.

due ruote 

But with a larger ring, wouldn’t each degree of turn of the eccentric move the teeth farther?

palincss

You shouldn't need a half-link to properly tension that timing chain. That's what the adjustable bottom bracket device is for. And it looks in this picture as though the timing chain is too long. And also, note that the cranks aren't correctly set either for in-phase or out-of-phase.

Aubergine 

The cranks were synchronized before I tested it! But the chain slipped. But you are right, I will try rolling the elliptic back again before trying the single link.

palincss

There's so much slack it looks like you may need to remove 1 or 2 links. In fact, you'd best check to see that the timing chain isn't stretched. Who knows how many miles are on it.

Aubergine 

I know how many miles are on it! Zero. The chain is brand new. Any flaws in assembly at this stage are entirely down to the incompetence of the mechanic, namely, me.

Random Tandem

After you get the timing chain worked out, you can try whether you like in phase, out-of-phase, or something in between. I prefer the back cranks 3 teeth behind the front cranks on my tandems as this helps smooth the weak spot in my stroke (as the stronger pedalling pilot, with one of my children as stoker) but it is close enough that I can put pedal at the top on the inside of a turn and know that the rear pedal will not strike. All of this you can try and see what you like best,but first lets get that chain on correctly.

First thing I would do is rotate the ecentric so that it is as close to the rear as possible, then make the chain as short as you can get over the chainrings. My guess is that this will mean that you need to remove a link. Then, rotate the ecentric until the chain tension only allows about a 6-10mm deflection in middle of the chain. Tighten the ecentric and rotate the cranks to see if there is another spot in the chain where it is much tighter or much looser. If so, you need to see if you can get the timing chainrings more centered on their cranks (I think sheldonbrown.com has a good section on some ways to do this). If the chain is much tighter at some point and you cannot centre the chainrings, you need to adjust the ecentric so the chain tension is correct at the tightest point.

Last note: often the bolts that hold the ecentric get really stuck and are hard to loosen after they have been left alone for a few years of riding in mixed weather. I recommend coating them in anti-sieze paste before you install them, and if there are through bolt holes use longer bolts that stick all the way through that you can put acorn nuts on to drive them out from the threaded end, rather than just relying on the hex socket in the head. I have had to drill out these bolts after the heads have rounded out and that is a very delicate job that involves a modicum of stress.

It looks beautiful and I am sure you will soon be enjoying the graceful power of a two-motored vintage ride.

-Will

repechage

No, remember you are dealing with arc length and circumferences. Setting up the timing chain taughtness required the aft chainring has to be held stable, I get the chain the correct length on top with the eccentric bottom bracket somewhere near high noon, then adjust the chain from there, if you have some slack, but cannot take a link out, hook it up and move the eccentric forward. I worry about crank angle timing last, after the tension is good. Everyonce in a while it goes well all at once, do not depend on it. There are schools of thought on how to set up the timing between the two cyclors. I would look at old pictures of the Herses on a tandem and go with that.

Aubergine 

Oh oh oh, I get it now. Thanks.

I have a half link and (more) knowledge now, so I bet I can get it set up properly tomorrow.