Tandem Cycling - frame design / construction

Hello,
My qustion is about modern frame design. Are the top and lateral tubes continuous from front (headtube) to back (stoker seattube), or, are the front and back diamonds built separately. I'm reading from the Paterek Framebuilders Manual (new edition) and the front, back diamonds are built separately, but I'm almost certain that most builders use continuous top and lateral tubes. Sorry if this is the wrong forum for this question, but I know that some of you are more than capable of answering accurately.

Thanks,
rlong

Co-Motion, Burley and some others use the continuous/pierced tube approach which is more labor intensive/expen$ive.
Santana, Raleigh, KHS and many others prefer the less expensive and less labor intensive method of joining tubesets.
We prefer the pierced/continous frame tubes; we feel it gives a much cleaner look and adds a bit more strength in critical areas.
We ride a custom carbon fiber ariZona pierced/continuous/lugged framed tandem.
Your choice . . . all these things are debatable, but after 30+ years of tandeming that's our preference.
Pedal on TWOgether into 2006!
Rudy and Kay/zonatandem

I'm reading from the Paterek Framebuilders Manual (new edition) and the front, back diamonds are built separately, but I'm almost certain that most builders use continuous top and lateral tubes.

As Rudy notes, it's a mixed bag as both methods are used and the construction methods / sequence varies as well. So long as the designer selects the right tubing, the person doing the fabrication knows how to weld, and they have the right size jigs and alignment tables, either method can be integrated into their frame designs. After all, it's the combination of the geometry, tubing material (type, thickness, butting), and joining methods that give a frame it's handling and feel.

IMHO, once you start getting into discussions regarding cost, complexity, and which is better or worse you've be drawn in to the marketing. Interestingly enough, even though Santana uses spliced tubes for most of it's tandems, you'll find that it uses a pierced tube on their most popular model of tandem's (i.e., Aluminum Sovereign) top tubes and while Co-Motion uses pierced top and internals on all of its tandems, at least a few years ago I'm pretty sure they were using spliced joints on the top tube's of its uncoupled triplets, quads, quints, etc...

However, that said, like Rudy I prefer the aesthetics of the pierced tubing -- particularly for road tandems which is what is used on our Ericksons -- but don't mind well-executed spliced joints, which is what are used on our Ventana off-road tandem.

As Rudy notes, it's a mixed bag as both methods are used and the construction methods / sequence varies as well. So long as the designer selects the right tubing, the person doing the fabrication knows how to weld, and they have the right size jigs and alignment tables, either method can be integrated into their frame designs. After all, it's the combination of the geometry, tubing material (type, thickness, butting), and joining methods that give a frame it's handling and feel.

IMHO, once you start getting into discussions regarding cost, complexity, and which is better or worse you've be drawn in to the marketing. Interestingly enough, even though Santana uses spliced tubes for most of it's tandems, you'll find that it uses a pierced tube on their most popular model of tandem's (i.e., Aluminum Sovereign) top tubes and while Co-Motion uses pierced top and internals on all of its tandems, at least a few years ago I'm pretty sure they were using spliced joints on the top tube's of its uncoupled triplets, quads, quints, etc...

However, that said, like Rudy I prefer the aesthetics of the pierced tubing -- particularly for road tandems which is what is used on our Ericksons -- but don't mind well-executed spliced joints, which is what are used on our Ventana off-road tandem.
Marketing aside, and I should say that I am not an engineer, I find it curious considering the forces applied by flex in top and lateral tubes, that anything other than a continuous, pierced tube would be as reliable. My question is spurred by my interest in building a lugged steel tandem, impractical as that is, and assumed the fewer joints the better, plus I to prefer the aesthetics of the continuous tubes. I will have to travel around and look at more of the hand built frames available in my area.

Thank you both for your replies.

I find it curious considering the forces applied by flex in top and lateral tubes, that anything other than a continuous, pierced tube would be as reliable.

Consider if you will, the most highly stressed areas of a tandem frame are the tube junctions at the tandem's headtube, bottom brackets, and top of the stoker's seat mast.... which are all welded using the exact same methods that a tandem builder uses to splice top and internal tubes to the lower-stressed junctions at the captain's seat tube. A proper weld is very strong and does not weaken the integrity of the tubing adjacent to the welds. IMHO, they are really manufacting and aesthetics issues:

1. Would you rather drill a hole in a long top or internal tube held in a jig and lay down two welds or, do you want to use beefier seat tubes, miter two tube ends, and lay down two welds?
2. Do you prefer the clean look of a pieced seat tube or an uninterrupted seat tube?

Consider if you will, the most highly stressed areas of a tandem frame are the tube junctions at the tandem's headtube, bottom brackets, and top of the stoker's seat mast.... which are all welded using the exact same methods that a tandem builder uses to splice top and internal tubes to the lower-stressed junctions at the captain's seat tube. A proper weld is very strong and does not weaken the integrity of the tubing adjacent to the welds. IMHO, they are really manufacting and aesthetics issues:

1. Would you rather drill a hole in a long top or internal tube held in a jig and lay down two welds or, do you want to use beefier seat tubes, miter two tube ends, and lay down two welds?
2. Do you prefer the clean look of a pieced seat tube or an uninterrupted seat tube?

Point taken. Ha!Ha! I feel like I'm back in my graduate statistics class, which I loved, but would occasionally make a most foolish statement directly followed by my mentors carefully thrown eraser and joyfull laugh. I can't believe I forgot about the much higher stresses at the bottom bracket and head tube:-)

So, another newby question; You have used the term "piercing" previousily, and in "1." you asked if I would rather drill a hole in the top and lateral tubes. Piercing is not used literally, correct? I mean with continuous long TB and LT the drilled hole is for escaping gasses from the mitered, beefier ST right?

Because I hope to use lugs as much as possible, and twin laterals (which I failed to mention) the clean look of an uninterrupted ST and TT can be achieved (except at the ST clamp, above the TP).

You have used the term "piercing" previousily, and in "1." you asked if I would rather drill a hole in the top and lateral tubes. Piercing is not used literally, correct? I mean with continuous long TB and LT the drilled hole is for escaping gasses from the mitered, beefier ST right?

Here are photos of the pierced top & internal tubes on our road tandems... they are both literally "pierced" by the smaller diameter seat tube. I've also included some spliced joint photos.

For visual reference, the first photo is of fillet-brazed joints and the top tube is ovalized, making it appear larger than it really is. The second photo is of TIG-welded joints which makes it even easier to see how the seat tube passes through the larger diameter internal and top tubes. The last image -- admittedly a poor resolution scan of the '06 Santana catalog -- shows what the spliced joints look like, where separate fore and aft top and internal tube sections are welded to the captain's seatpost. The last image is of the top tube & seat tube junction on our Ventana which, again, is spliced.

Here are photos of the pierced top & internal tubes on our road tandems... they are both literally "pierced" by the smaller diameter seat tube. I've also included some spliced joint photos.

For visual reference, the first photo is of fillet-brazed joints and the top tube is ovalized, making it appear larger than it really is. The second photo is of TIG-welded joints which makes it even easier to see how the seat tube passes through the larger diameter internal and top tubes. The last image -- admittedly a poor resolution scan of the '06 Santana catalog -- shows what the spliced joints look like, where separate fore and aft top and internal tube sections are welded to the captain's seatpost. The last image is of the top tube & seat tube junction on our Ventana which, again, is spliced.

I hardly know what to say or, where to start. I'm stunned! I'm sitting here looking at my Burley Rock n Roll with "pierced" top and lateral tubes and had a completely wrong vision of how they had been constructed. I thought the ST was mitered and brazed in separate sections. I would never have dreamed that you could bore a 1" + hole through a larger TT and LT then slip the entire length of ST through it. Your pictures were like a revelation to me. Thank you for this posting.

The Santana pictures came through just fine and is a method that I am also interested in for a tandem. So many single bike builders seem to have used this method of joining carbon tubes and I think it would also look excellent with carved lugs. I wonder about the labor involved to keep the short tubes aligned well enough to accept the carbon tube inserts. Talk about a LEGO project! Definitly not for the one off builder I would think. But I'm begining to see that my vision is a little limited by my inexperience.

If you are planning to use twin laterals, be sure to put re-inforcing bridges between the two sets of laterals!
Just running the laterals from head tube to pilot seat tube and then to rear bottom bracket and brazing them in place will not be sufficient. Be sure to add at least one or two bridging tubes between the twin laterals as re-inforcement.
Gitane (and a few others) used to build twin lateral tandems and neglected to put in bridging tubes resulting in a bit spongy ride.
If you add some nice lugs to that, you'll come out with a real nice retro-look tandem!

Pedal on!
Rudy and Kay/zonatandem

I didn't really notice a

If you are planning to use twin laterals, be sure to put re-inforcing bridges between the two sets of laterals!
Just running the laterals from head tube to pilot seat tube and then to rear bottom bracket and brazing them in place will not be sufficient. Be sure to add at least one or two bridging tubes between the twin laterals as re-inforcement.
Gitane (and a few others) used to build twin lateral tandems and neglected to put in bridging tubes resulting in a bit spongy ride.
If you add some nice lugs to that, you'll come out with a real nice retro-look tandem!

Pedal on!
Rudy and Kay/zonatandem
Right you are Rudy, plus the bridges are the mounts for water bottle bosses, so you really need quite a few of them. I believe this is part of the reason they were discontinued, due to the intense labor involved even when the bridges were mass produced.

Right you are Rudy, plus the bridges are the mounts for water bottle bosses, so you really need quite a few of them. I believe this is part of the reason they were discontinued, due to the intense labor involved even when the bridges were mass produced.
But of course the Dutch bicycle wiseguys Koga saw reason in the 2005 model year to 'recontinue' twin laterals ......

http://www.koga.com/upload/collections/8392451.jpg

And in 2006 livery:
http://www.koga.com/upload/collections/698207.jpg

Yes: the top tube is bent :o

The Dutch tend to be a bit more practical/traditional design-wise on their tandems. However, having said that, the Koga Myata Twinn Traveller is a real exception to this statement!

But of course the Dutch bicycle wiseguys Koga saw reason in the 2005 model year to 'recontinue' twin laterals ......

http://www.koga.com/upload/collections/8392451.jpg

And in 2006 livery:
http://www.koga.com/upload/collections/698207.jpg

Yes: the top tube is bent :o
Martin:
I went to their website hopeing to see another view of this bike, alas this is it. I had no idea anyone was producing twin laterial tandems anymore. I don't care much for the marathon look with separate sets of laterals in the front and back, but still, pretty amazing bike.

Not to change the subject, but sometime last Spring I recall a rather extensive article about vintage european tandems used for racing, but I can't recall the publication, or, find it now. I get Velo News, Bicycling, RTR, and Adventure Cycling. Does anyone recall this article? There were a number of excellent pictures included.

Not to change the subject, but sometime last Spring I recall a rather extensive article about vintage european tandems used for racing, but I can't recall the publication, or, find it now. I get Velo News, Bicycling, RTR, and Adventure Cycling. Does anyone recall this article? There were a number of excellent pictures included.

It was probably Jan Heine's article in Recumbent & Tandem Rider Magazine (I don't recall which issue) or, perhaps, in his own publication Vintage Bicycle Quarterly (http://www.vintagebicyclepress.com/vbqindex.html) (Vol. 2, No. 1 from Autumn 2003) that discussed his use of a restored 1947/8 René Herse tandem for the '03 PBP. He and his partner were the fastest mixed tandem team in '03.

http://www.vintagebicyclepress.com/images/pbpcornervillage.jpg

More photos here: http://www.vintagebicyclepress.com/images/HERSETANDEM.jpg

The Dutch tend to be a bit more practical/traditional design-wise on their tandems. However, having said that, the Koga Myata Twinn Traveller is a real exception to this statement!
It sure is. For those who don't know this bike, here it is:

http://www.koga.com/upload/collections/6358760.jpg

This is indeed a different approach! It's very comfortable and quite heavy at 30 kgs, although with all this equipment that's not even too bad a score. Since the 2005 model year it's foldable, that's why the double clamps are in the middle section. I must say they did a smart job of that feature, because the bike now even sports two small 'pulleys' at the left side where one can store the timing chain when the bike is folded. And this foldability solves a problem that people actually have, which is not usual in marketing :rolleyes:

Although it's not for us personally (too heavy, cumbersome handling in corners, vulnerable rear suspension) it's a great success in the European tandem market.

Look at the faces! He is busting his butt and she is checking out the scenery!!!

Martin:
I went to their website hopeing to see another view of this bike, alas this is it. I had no idea anyone was producing twin laterial tandems anymore. I don't care much for the marathon look with separate sets of laterals in the front and back, but still, pretty amazing bike.
Well, if you get to know Koga it's not too amazing to find they're using this ancient building technique. This company (that builds really fine bikes) sometimes wanders from the 'normal' paths just to be different, if you see what I mean. In my opinion, this twin lateral design offers no substantial advantages, it only looks different. And I personally don't like the slightly bent top tube. But that's just me ..... you can't argue about taste, as they say. Which is good because the 2006 colors are, well, they attract attention ;)
There is only one thing that I really don't understand about this tandem: it's a 26"-wheeled, properly made and reasonably sized and priced tandem, fit for long-distance cycle camping. So why spec a standard XT rear hub, not the tandem variety with threading for the drum brake?

You should know that Marten, the Netherlands is flat - no need for serious brakes. No, seriously it seems like a major omission, though it's the sort of thing that most non-tandemists would overlook until too late.

God that is one ugly bike.....

It was probably Jan Heine's article in Recumbent & Tandem Rider Magazine (I don't recall which issue) or, perhaps, in his own publication Vintage Bicycle Quarterly (http://www.vintagebicyclepress.com/vbqindex.html) (Vol. 2, No. 1 from Autumn 2003) that discussed his use of a restored 1947/8 René Herse tandem for the '03 PBP. He and his partner were the fastest mixed tandem team in '03.

http://www.vintagebicyclepress.com/images/pbpcornervillage.jpg

More photos here: http://www.vintagebicyclepress.com/images/HERSETANDEM.jpg
It could be RTR mag. I can't find issue #18, or anything before #17, so it probably got tossed. I don't get Vintage Bicycle Quarterly, so that wasn't it. Dang, I really ment to keep that to. Thanks for looking.

It could be RTR mag. I can't find issue #18, or anything before #17, so it probably got tossed. I don't get Vintage Bicycle Quarterly, so that wasn't it. Dang, I really ment to keep that to. Thanks for looking.

I'll check when I get home...

http://www.koga.com/upload/collections/6358760.jpg

Is that a parking lock on the rear wheel, at about 1:00?

-Greg

Here are photos of the pierced top & internal tubes on our road tandems... they are both literally "pierced" by the smaller diameter seat tube. I've also included some spliced joint photos.

For visual reference, the first photo is of fillet-brazed joints and the top tube is ovalized, making it appear larger than it really is. The second photo is of TIG-welded joints which makes it even easier to see how the seat tube passes through the larger diameter internal and top tubes. The last image -- admittedly a poor resolution scan of the '06 Santana catalog -- shows what the spliced joints look like, where separate fore and aft top and internal tube sections are welded to the captain's seatpost. The last image is of the top tube & seat tube junction on our Ventana which, again, is spliced.

TandemGeek:
I forgot to ask about those beautiful fillet brazed joints on the two pictures. Are they taken from your Ericson's, the most beautiful tandems built, as I believe they are described by the builder. Wow, those are really smooth! Ovalized top tubes are not too common on tandems are they? How would you describe the effect they have on the ride of these bikes?

It could be RTR mag. I can't find issue #18, or anything before #17, so it probably got tossed. I don't get Vintage Bicycle Quarterly, so that wasn't it. Dang, I really ment to keep that to. Thanks for looking.

It's issue #18, pps 30-33.
A Look Back At Tandem History by Jan Heine

Back Issues of RTR can be obtained for $5 from:
Coyne Publishing
P.O. Box 337
San Dimas, CA 91773

The color photos of the 7 tandems discussed in that article, along photos of 50 other classic French bicycles are included in this book: http://www.vintagebicyclepress.com/goldenage.html

I forgot to ask about those beautiful fillet brazed joints on the two pictures. Are they taken from your Ericson's, the most beautiful tandems built, as I believe they are described by the builder. Wow, those are really smooth! Ovalized top tubes are not too common on tandems are they? How would you describe the effect they have on the ride of these bikes?

Yes, those are photos of our two Erickson tandems
'98 fillet brazed Signature Model Tandem (http://www.thetandemlink.com/LGood/EricksonInfo.html)
'02 TIG-welded Custom Travel Tandem (http://www.thetandemlink.com/LGood/ericksontravel/Ericksontravel.html)

The fillet brazing is amazing... on par with a monocoque carbon frame joint (See photos below). On my solo Erickson (Deddacai & Prestige) the joints are all fillet brazed with the exception of the head tube / down tube which uses a hand-carved lug, another one of Glenn's signature features.

http://www.thetandemlink.com/LGood/BikeImages/ericksonlugsm.jpg

As for the TIG welding, they were as minimal as you'd find on a steel frame up and until two years ago when Co-Motion came out with what are most incredibly small and tight TIG welds I've seen on any material... a thing of beauty.

As for the ovalized top tube, I believe the only builders who continue to use it on a regular basis are Glenn & Rodriquez (built by Dennis Bushnell). When Lippy was still building tandems he used it for his internal tubes. The ovalized top tube on our rigid Erickson is custom drawn, straight gauge 4130 sourced locally in Seattle, WA along with the oversized & butted boom, down, and internal tubes. Each of these custom-drawn tubes, along with the Prestige seat tubes, have different diameters, thickness, and shapes as specified by Glenn to achieve the desired ride characteristics needed for each team for whom they're designed. While it sounds strange, Glenn takes each customer's requirements and then applies his philosophy on tandem handling, comfort, and performance to come up with what is always a truly unique frame design that extend well beyond the paint scheme.

Back to our Signature tandem -- which is more true to Glenn's philosophy than the S&S model where the couplers constrain some of his designs -- the ovalized top tube and internal tubes are both oversized, thick gauge 4130, which gives the very long stoker compartment (31") the torsional rigidity needed to prevent the frame from twisting under sprinting or out of the saddle climbing loads. The rigidity is further enhanced by the steeply sloping top tube, extremely short stoker seat post, very low rise seat stays, and very stiff chain stays (they're made from Prestige fork blades) which in effect is a compact frame design that Glenn embraced well before it showed up on solo racing bikes. In contrast, the down and bottom tube are both very large diameter, thin gauge tubing with the downtube being horizontally ovalized at the head tube, and laterally ovalized where it joins the bottom bracket. The boom tube is ovalized and butted. You'll also find on close inspection that the seat tubes are externally butted where they join the bottom brackets and top tube. So, when all of these features are put together you end up with a very long tandem that resists torsional flex (ovalized top, bottom & down tubes) as well as the excessive lateral flex you'd expect to find on a very long frame (round, robust internal tube).

While not incredibly light at 37lbs with a steel fork, it was 2 lbs lighter than our Santana Arriva despite having a 4" longer wheelbase. As for the handling, it was a completely different ride than the Arriva which, after all, is what you'd expect from a custom performance tandem designed for you vs. a production tandem that was designed to perform well for a wide range of buyers.

So, despite being labelled as a low-tech / high-tech looking fad from the '80's by at least one mass-producer, that critique fails to acknowledge how the ovalized tube is integrated with the rest of the tandem's design... which is to say it works quite well for us and the rest of the folks whom we know that ride Ericksons or Rodriquez tandems. BTW, Rodriquez tandems were originally designed by Glenn when he and Angel Rodriquez formed R&E Cycles in Seattle back in the 70's. Angel left the bicycle biz. many years ago, about the same time that Glenn began building frames under his own brand name. Dennis Bushnell is the constant in the Rodriquez brand... which is to say, they are excellent frames (as are Bushnell's own name branded tandems).

You can read David Morgan's review of Glenn's personal '97 Erickson here at the TandemMag.com archives: http://www.tandemmag.com/roadtest/erickson97/

Bear in mind, the Aeramet top & internal tubes were pretty much unique to that frame and the greatest benefit was the weight savings. So, as you read the article you need to recognize that the comments about the Aeramet were a bit overstated in that with the exception of the weight savings, all of Glenn's tandems exhibit similar handling, performance, and comfort... even the S&S equipped tandems. The S&S models are noticably more stiff than the non-coupled models, but otherwise share most of the other ride characteristics. Also recognize that each Erickson tandem has different components based on buyer preferences, what was available at the that time, and what ever Glenn happened to be playing around with at that time.

For comparison, here are photos of the TIG welded frame's key joints:

Look at the faces! He is busting his butt and she is checking out the scenery!!!

Not likely... That's Jaye Haworth stoking for Jan. She is a very accomplished member of the BC Randonneurs Cycling Club who regularly participates in solo brevets of 200k - 600k. She's also very active as a cycling advocate in Toronto, coordinating annual "Car Free" events and other worthy causes associated with serious cycling.

It's issue #18, pps 30-33.
A Look Back At Tandem History by Jan Heine

Back Issues of RTR can be obtained for $5 from:
Coyne Publishing
P.O. Box 337
San Dimas, CA 91773

The color photos of the 7 tandems discussed in that article, along photos of 50 other classic French bicycles are included in this book: http://www.vintagebicyclepress.com/goldenage.html
Thanks Mark, and I can't believe that issue got tossed out. On the bright side, I was thinking of buying the Golden Age of Cycling, but wasn't sure if there would be many / any tandems in it. Now I have a good excuse to get it.

For comparison, here are photos of the TIG welded frame's key joints:
Quite a difference in two styles of welds and an amazing opportunity to see the two, nearly identical bikes side by side for comparison. Thanks again. I'm going to learn TIG welding from my son who does aerospace stuff at work, but off-road suspension designs for a hobby. Unfortunatly everything he does tends to be BIG and he is the first to admit that his style doesn't really lend itself to bicycle frames. So, I have to start somewhere and that's ok for now. I'm really more interested in brazing, but I believe you need to know how to do a good TIG as well.

Referring to the picture of the Koga Miyata Twin Traveller tandem:

Is that a parking lock on the rear wheel, at about 1:00?

-Greg
Yes, it is. It's standard issue on most Dutch "town and trekking" bicycles. It's also obligatory (in most cases) to get the bike insured. And one can add a steel cable-with-eyelet to secure the bike to something fixed like a lamp post.

"Clash of the Titans"
Just finished reading this article published in Tandem and Recumbent Magazine and reprinted on the Precision Tandems website under the Longbikes dropdown. It really is interesting and worth the reading. The bikes included in the "Shootout" are Co-Motion Java, Santana Sovereign, Cannondale RT2000 and Longbikes 300RS. The LongBikes 300RS scored considerably higher than the others in all catagories except one tie for seated climbing with Santana Sovereign.

The Longbikes uses steel, (Truetemper?)OX3 oversized tubes it designates as "COLT" (continuous oversized long tubes). There isn't too much more information about the tube sets and Longbikes own website is currently dedicated to recumbent bike information that they are building now. They still build tandems, but don't say anything about them, as they are custom only.

Anyone have knowledge of this amazing bikes design? I understand that the competition out there is just awful for a new builder (keep the day job), but to beat out all of these very commercially successful bikes in so many areas demands a more detailed examination of the design used by Longbikes. Are they just using oversized tubes, and if so, do they weigh a ton, are they shaped tubes. Precision is practically giving these things away. I want to know more.

How does the KHS Tandemania Alite get away without a tube running all the way from the head tube to the rear bottom bracket. Maybe they wanted it flexy for a smooth ride?

Alite (http://www.khsbicycles.com/11_alite_06.htm)

Longbikes? Anyone? See my previous post.

Me thinks Paterick does not know what he is talking about. We may have been the first to use continuous long tubes and coined the acronym "COLT" Continuous Oversize Long Tubes. We did this in about 1989. It has been the standard method by all reputable builders for quite a few years now.

Greg Peek
Longbikes
www.longbikes.com
greg@longbikes.com

There are some Longbikes frames kicking around here and there. I test-rode one and found it to be a very nice machine - very stiff frame. I think the design is about 10 years old or older. However, I think for a premium frame, you would be hard-pressed to get the Longbikes much under 40lbs built up. Also, steel frames from Santana or CoMotion may have already surpassed it in stiffness and light weight.

And what about our frame choice, double lateral tube on titane frame, see:
http://enfinletandem.blogspot.com/2005_11_01_enfinletandem_archive.html
Jean-Yves and Dominique
Lot
France

Me thinks Paterick does not know what he is talking about. We may have been the first to use continuous long tubes and coined the acronym "COLT" Continuous Oversize Long Tubes. We did this in about 1989. It has been the standard method by all reputable builders for quite a few years now.

Greg Peek
Longbikes
www.longbikes.com
greg@longbikes.com
Greg,
Thanks for taking the time to reply to my question. It does seem that Paterick included the tandem building portion of his manual under some duress. There isn't even a word about continuous, pierced top and laterial tubes. I wish there was some alternative guide, in addition to Paterick, to tandem building. Which leads me to the following questions. I'm curious as to the sort of tubing you are using these days for your tandems, and why do you think your tandem outperformed the others in the "Shootout" article.

Thanks,
rlong