bulgie 

Ah, what to call that tube? Santana calls it a lateral tube but I believe that is wrong, lateral meaning "to the side" so I use laterals to refer to those smaller tubes that are used in pairs spaced out to the side, like traditional Mixte frames. Usually used as "twin laterals". Santana says no, their laterals are "internal laterals"; internal meaning "in the plane of the bike", with lateral meaning more like "going from side to side". But they don't go side to side, IMHO they go front to back (sort of). Their original design, based on one of the designs Jack Taylor used to make, had the "lateral" from the head tube to the rear dropouts (with mid-stays); this was called a Marathon (named by the Taylors I believe). Later they (Santana) changed to the one with the bracing tube from the head to the R BB, which they dubbed the "Direct Lateral" and which they claimed to have invented, though it was used decades earlier. (Dunno if they knew that).

Anyway I just call them bracing tubes, though that's not really meaningful to most people. I don't think there's a generally-accepted term.

Now, do bracing tubes (of any config) do much? Debateable, but we know they aren't needed, because there have been lots of excellent tandems with the "open frame" config = zero extra bracing tubes. That style requires the outer tubes like TT, DT, keel tube etc to be large diameter. I'm pretty sure that if you remove the bracing tubes and use that same amount of steel to make those outer tubes larger diameter, the effect will be a stiffer frame, in the ways that matter (lateral and twisting stiffness). Diameter trumps all. There's no internal bracing scheme that can beat that.

With no bracing tubes, the rear parallelogram* consisting of both seat tubes, the R TT and the keel, depends of the stiffness of the joints to keep it from "parallelogramming". (Hint: imagine if the joints were hinges...) But the vertical compliance this gives is seldom considered a bad thing. (*yes I know it's not really a parallelogram unless the TT and keel are parallel and both seat tubes are parallel, but for the purposes of this armchair engineering exercize, let's pretend it's a parallelogram for simplicity.)

Note, everything I just wrote is considered controversial by some people. Of course I just think it's 100% correct...

I don't consider that a large keel tube, in fact it's a bit paltry (though I like Burleys in general, great value bikes). Earlier Burley frames like this used a single bent tube as the DT and the keel, so the size is a compromise. If it were big enough to be a proper keel, it would be too big (for steel) as a DT. Later Burleys switched to a more normal design with separate DT and keel, the latter being much larger. They also ditched the "loop stays", switching to separate chainstays and seatstays, a pretty good improvement.

Yes, I have a Burley that I was given for free because the cap'n ST is rusted completely through at the BB. A shame, because the bike doesn't seem to have been ridden much. I think rain got in while they were carrying it on the car. It's one of the newer designs I prefer, separate keel, and separate rear stays, with the chainstays being nicely oversized. So I do think I will repair it one of these days.

But as discussed already, tandems are hard to sell, so if I repair it I won't be able to sell it for much, and it's not my size. Plus I have 2 other tandems already that I like a lot.

Mark B

rjhammett

I hope you have someone that is really interested in riding with you. I picked up these two for my family thinking it would be something fun. We rode about a mile and the rest of the family said it wasn't for them. I now have two tandems in my garage I need to get rid of.

cyccommute 

The curved tube on the stoker seat tube is a fix for a problem the earliest Gitane (and other tandems) had. With a straight seat tube, the stoker was moved forward which significantly reduced the stoker’s space. My tiny wife had trouble dismounting because the space was so small. The real problem with that fix, however, is a very limited saddle height adjustment. The top of the seat tube is going to be very high…not optimal for a small stoker…and the ability to move the saddle down is going to be very limited. Putting the stoker that far back over the wheel may also have some impact on the handling. I’d probably pass unless your stoker is close to your same height.

Burley’s are a good place to look. I have had a Burley Duet and Samba from the 90s. The Duet was a better tandem. Our Samba doesn’t have the rear triangle tube that rjhammett’s does which makes it a much more flexy ride. It’s not a great tandem for two adults. It’s currently set up for kids to ride the back. It works well for that application.



My wife wants to try touring so we bought a tandem in 2021. It’s a 2010 Cannondale and is a great tandem! It’s a XL/XS which means that it is a 58cm front and 43cm rear. Perfect for my tiny wife. She can get on and off it and still stand flat footed if she wants. That wasn’t possible with either of our Burleys. The Cannondale is worth looking for if you want a Tandem.



If I were a newbie to the tandeming world, I’d probably try the Gitane to test the waters…free or cheap is good…however don’t expect much out of it. Look for better and pass this one along.

jonwvara 

Thanks for a really informative post.

Wildwood 

CoMotion's beam for the stoker on this '97, makes it highly adjustable. Saddle fore & aft ('top tube') as well as for a range of 'seatpost lengths'.

RCMoeur 

Have to say I agree with most everything posted here.

The first tandem I owned was a "bargain brand" that (even with a fat boom tube) was so whippy I couldn't trust it cornering. As disastrous as the relationship that triggered its purchase.

My next girlfriend said she'd like to try tandeming. Now I'm a proud member of the Compact-American Community and in the 7th percentile of male height, whereas she... isn't. And I'm the experienced one and she's the "I just want to pedal and look around" type. So I'm in front. We tested a Santana on a hot summer weekend, and it was a death march with water problems and several discomforts and malfunctions. She was in tears when we finally made it home, and I figured that was the end of that. But after long showers and refreshment, she said, "so when are we buying one?"

We were able to get an Santana Vision 26" wheel in extra-small, that I straddle perfectly and was easily adaptable to her needs with upswept riser bars in the rear and a long seatpost. And the Santana frame is dead solid and predictable, with zero whip, even when she gets fidgety. Nearly 30 years (24 married) and 4000+ miles later we still have that bike. Alas, her knees are bad and she can't even swing her leg over the top tube anymore, but we're hoping that might change someday and we'll hang onto it until then. My son's ridden it quite a few times with me as he grew up, but for the past 4 years or so anything Dad-related is not even considered as an option, so it continues to wait patiently for its next ride.

Milepost105 

This Paramount tandem is on eBay, near me. I was tempted to make an offer, but frame size is too small for me, too big for my wife. I have finally learned to resist the slightly wrong frame size trap.

https://www.ebay.com/itm/Vintage-197...p2056016.l4276

bark_eater 

Going to quickly crash this party... I've got a skinny tubed Gitane taking up space on the Eastern Shore of Maryland. I will most likely strip it at some point for all the cyclotourist bits that will fit a single seater. And then there will be a frame available. Thats the public service broadcast for the day.

merziac

So it was abandoned because......

Did it ever work for you?

bark_eater 

I never gave it a chance. I picked it up for the Mafac cantilevers and the TA and simplex drive train as part of a deal that involved unloading all the bikes my kid had grown out of and a reasonable sum of money. I'm not a small person and probably max out the design spec all by my lonesome, and it will be a while till my kid is big enough for such things.

I was just mentioning it as I assume that while there are very few people who want a tandem, much less a partially stripped project, the folks in this thread are the likeliest candidates..

merziac

Gotcha, Mafac canti's and TA.

due ruote 

I'll throw out another vote for a used Cannondale. They seem to be pretty plentiful. We paid about $600 for a used 2005 model a couple years ago, which seemed like a pretty solid deal for a 9 sp Ultegra equipped bike with disc brakes. It's our third tandem (preceded by an alloy Santana Sovereign - nice bike but a size too large - and an Ibis with 26" wheels). We still have the Ibis and it's a lovely smooth ride, but it's a good 9lbs heavier than the Cannondale, and not nearly as rigid, despite OS tubing. On the Cannondale I don't feel much frame flex at all, but it also doesn't feel harsh. We have 38mm Soma Supple Vitesse tires on ours, which is the max. width it can take.

bulgie 

That's the very definition of a terrible old tandem to avoid. The R TT is actually shorter than the F TT, which might sound OK until you remember the front stem faces forward, rear stem faces back. R TT is 56 cm, which is about 10 cm (4") too short.

Maybe counterintuitive, but a too-short R TT actually works better when the two riders are near the same size. At least for a racy bike where you're leaning forward. Then the taller stoker's head will be close to the captain's back, where the smaller stoker will have her nose in thecaptain's butt. The alternative is to set the stoker sitting straight up. When you can't lean forward, all your weight is on your butt. Unhappy stoker means the bike won't get ridden. Lots of those Paramount tandems look mint!

The story I heard (maybe someone here knows the straight poop), the first Paramount tandems were for track sprint. Track sprinters are pretty much all big, and for sprinting you want the bike as short as possible since the event really only lasts ~10 seconds (the sprinting part). Comfort is no issue at all, and tightly packing the riders together makes for better drafting. Then later when they made road tandems, they just put different dropouts on their track design, on the same jig.

For a touring bike, that's just malpractice. And by touring I mean anything other than actual racing. Even for a pure racing bike that's too short for most people. Racing tandems nowadays are made with long R TT.


The tandem I made for me & Laurie in about '89 has a 66 cm R TT and I wish it was longer. (She's a petite 5' 4", likes a 52 cm TT on a single.) I made the tandem that short because I wanted to use a Columbus Max seattube as the R TT, and 65 cm is how long they come. (With a sloped TT, the effective length can be a little longer than the actual tube.) But even with the reach to the bars a bit shorter than on her single bike, her bars are still uncomfortably close to my ample butt. Can't use a shorter rear stem to lengthen her reach because her knuckles would be hitting the back of my thighs. They already hit a little. To mitigate that, I have set my saddle farther forward than I like. If I make another tandem, it'll have a R TT at least 72 cm. Though that might sound long, it actually is what's required to duplicate her single-bike position with that 52 cm TT.

Take her preferred single TT length and add the length of both stems — the stem on her single, and the stoker stem on the tandem. A stoker stem should be at least 12-13 cm long to keep stoker knuckles away from cap'n thighs. If her single stem is 7 cm, you can see the tandem R TT needs to be at least 19 or 20 cm longer than the single. Even longer gives you more choices in where to put the stoker bars without interfering with cap'n butt.

I often hear people say the stoker position doesn't need to be as stretched out as that rider's single bike position. The people saying that usually aren't stokers — not if they're experienced, hard-riding stokers anyway. Would you give up the ability to lean forward and stretch out a bit, or the ability to climb standing? Beginners often think they want to sit straight up, but put in a few more miles and they'll see the advantage of taking some weight off the saddle.

Mark B