From earlier in the thread those people are riding the tandems either not -or barely- encumbered and they have riders jump on now and then for a few miles, they are doing it for the joy of riding freely like that. As a poster before in this thread said the better of the cases weigh in at ~17lbs each [expect 2x 20-24+lbs for ones you could afford to destroy], add in tube/ bar stock to attach it to the frame in some way [easily 10-20lbs, maybe up to 50lbs to help support the weight], add in the weight of the bike [a 'typical' complete touring bike by itself is 28-30lbs typically, for your bike frame and some components I would estimate 50-70lbs because of the home made couplings, fact it is most of two bike frames, a lot of chain] so for the bike with the box sides it should weigh 80-130lbs unloaded, add in water [heavy!] and your gear [you will probably over pack because of the size of the boxes] and the loaded be weight could be pushing 200-300lbs easily, then add you and -no offense- your built frame and couplings will not be able to handle that. None of that is factoring costs of things like the stupid expensive cases, or the water system, or the frame and other parts, or the cost to fly those heavily loaded boxes.

Conversely a cheap Windsor Tourist [$600, ~28lbs, add in a good wheel truing and tension for $50 -though a decent road bike with provisions for a rack and a replacement front fork will weight just over 20lbs], a rear and front rack [maybe $200 for good ones, 5-10lbs], panniers for the front and rear [under $200 for 2 sets, 5-10lbs], large duffel bag(s) [or just disposable bike cases] and the unloaded weight will be about 40-50lbs add in a lot of stuff [it may not seem it, but it will be more than you need as well!] and the loaded weight will be 100-150+lbs, add you to that and you should be well within the bikes limits, and that's traveling with more stuff than you would know what to do with.


You need to consider the comfort of the ride, ease of pedaling [your ability to peddle directly works into this, can you hold 20mph or so heading into the wind for over 9 miles? and can you hold a line while going over 17mph with a wind blowing from your side? what is the most weight you have comfortably hauled for over 9 miles, and at what speed?], also, with the lighter bike with less stuff on it you are wasting far less energy moving the bike from point A to point B and thus do not need to recover as much with water/ food and thus the smaller amount of supplies will work better for you; as a bonus you don't die from heat stroke/ exhaustion/ getting so exhausted you swerve into something solid/ won't have trouble stopping in time for something/ no trouble avoiding road hazards completely / and won't likely fall [from exhaustion] or get blown over into traffic [those would be negatives of the massive design you have, rest assured in the last scenario because of the sheer bulk-weight of the bike and stuff the offending vehicle will likely be totaled on the front end]

I'm really trying to help you, you just need to understand that what you are proposing is like using a weed whacker's 2 stroke to drive a large boxvan; to put it simply the engine [you] will not enjoy it for long and will get burnt out needlessly.



Probably the best route if you want to avoid the costs of airlines and all [how far are you traveling anyways? have you considered hitching a ride on a ship?], what better way than to rent/ buy a bike at the destination, buy a good deal of the gear there, and bring minimal stuff, that way you can travel there light/ cheap and just visit a bike shop there, get it fitted, pick up the stuff and be on your way, then return/ sell the bike back to them when you are done to make back most of the money [you are initially spending less money this route anyways, and you will enjoy it more as well]. I would visit there/ be in contact with a few bike shops now and work out an agreement for a rental/ sale and buy back of a touring bike in your size and the gear you will buy there, not only do you get to support a bike shop then, but also the tourist economy, and you will have a better time.

This thread is a wondrous, amazing ode to silly, silly awesome. I am so happy right now.

Based on what has been said (and not said) in this thread and the idea itself im not sure the op has ever ridden a bike, let alone a tandem bike, let alone been on a tour of any kind.

Six pages of why this is one of the worst ideas any of us have ever heard, as well as people offering myriad sensible solutions, and OP has an answer for everything. Nobody can be this dumb in real life and still be capable of using a computer.

Go build your goofy contraption. Everyone else, I suggest we stop feeing the troll.

"Why not?" You're right, nobody has a good reason. Satisfied?

And no, I'm not being supportive. I can't support imbecility in good conscience. If you can make it work, go build it and prove us all wrong.

- Long frame is not crazy, or really worth getting all exercised about. It obviously isn't conventional, but this kind of 1.5 frame has plenty of track record. You probably need to square the % increase to get the weight increase, but it is not going to be all that great, and makes for a real Cadillac ride.

- If you really mostly need the extra load capacity to carry 20 gallons of water, that just scream trailer, if you can find a practical one that will carry that much. Unfortunately stuff like the Bob is limited to 30 kg.

- 48 spoke wheels are nice, I would go for them. But I have been 340 pounds loaded on the bike, and had no problems with 36 spoke wheels, 32 spoke 26" wheels. More spokes are better. soldered spokes are not a good idea. You need to be able to wrench on the wheel, and a lot of spokes should deal with load issues. What value if any that soldering produces is open to question, so I would drop that as just another out there idea.

- I don't see any reasonable way to make all this packable, but if you can see your way to there, good ho.

Have you talked with any frame builders who might want to do this? Sadly such bikes often overshoot available tooling. When I got my anvil jig, I thought for 4 K it would handle bikes like this, which I wanted to make, but no such luck.

they sell a tandem add-on that would be a start. I built my tandem without a jig, it was a lot of work though.
I was thinking about building something like a big dummy, I just realized my jig will not accommodate that configuration.

I think a tandem or anything larger than a regular touring frame is unneeded overkill. I know people use Big Dummy's for touring, but that seems like overkill too. You still have to get the bike and gear up all the hills. The less weight the easier that is.

This is the antidote to the "ultralight evangelism" thread........but one is far more reasoned and practical than the other. Still I look forward to design drawings, gear lists and pictures of the final bike.

One example the Tour Easy Le, 66" wheelbase. The OP is probably talking in the range of 56. The LE while not my thing, is a widely beloved touring bike, and people in particular like the long wheel base ride. Well regarded maker of touring bikes Thorn, has a long wheel base touring bike I'm not too sure how long it is, but only a few inches overlength, but still, goes to show there are differences of opinion on this stuff. And while I think there are questions about the experience level of the OP, based on some of his comments, long wheel base bikes probably aren't all that well known either. Ok, maybe for good reason, or not.

The Thorn Sherpa has a pretty long wheelbase. A bit off topic but what do you think of Thorn's marketing material????

https://www.sjscycles.com/thornpdf/Th...paBroLoRes.pdf

how much is this going to cost when flying?

you're going with the standard-sized luggage to avoid the sporting equipment fee,
but in exchange you're going to be 50-60 pounds over the weight limit.

that's going to cost you how much?
$300-500 each flight in excess baggage fees?

Yes, it will.

Most trailers tend to be in the rider's slipstream, and will have a significantly better aero profile than one person on a tandem with two massive cases bolted to the side.

Even a Burley Flatbed piled with crap will work better than what you're proposing.

Not to mention stability in a crosswind. Yikes!

There's a lot of negativity in this thread, and although I may not be on complete agreement with all the concepts myself - without people with different ideas, we wouldn't have recumbents, or ebikes or folding bikes either.

So just a few things to consider: Companies like CoMotion and Rodriguez already make tandems that'll break down and fit in two airline legal cases - so there's no reason to believe that something smaller ( like whats proposed here) wouldn't as well.

And weight is a relative issue - something that the right gearing can often get around. There have been bicycles built to do nothing except collect and transport paper for recycling. Those were capable of handling a payload of 300kg so on reasonably level ground - it can be surprising whan can be pushed around with just pedal power. Cargo bikes are common around the world and some models are rated for 700 lb loads.

Full size folding tandems are available at 35lbs or less. No reason to insist that an abbreviated version has to weigh more. Hard cases do run around 17lbs, but soft shell cases can be as little as 7 lbs each. Most have wheels. My biggest concern is that I have never tripped across any that were waterproof.

So lets not judge everything simply becaused its not exactly what we'd do ourselves. I have a friend that thinks absolutely nothing of loading 125 lbs of beer, fishing and camping equipment on a bicycle and going fishing for a couple days. Surprisongly - his wife does the same thing. Some of the stuff they use is custom adapted to their bikes, some of it is specifically designed to protect and transport fishing equipment, and a couple items were interesting enough that apparently Shimano bought the patterns.

If you told me there was a market for a folding tandem for four people I'd find that hard to believe too, but apparently there is and a few companies make them. Different strokes for different folks.

I think you are confusing negativity with people expressing their doubts about the OP's plans. Like you say, people have different ideas, and all they are doing here is expressing them. This would be quite a boring place if everyone who posted agreed with one another, and those that disagreed remained silent.

To me, this sounds like a question for the Frame Builders forum.

I would think the pluses would be less bumpy ride, huge carrying capacity, one-of-a-kind bike. Negatives would be potentially wobbly ride due to flame flex and/or weight distribution, heavier than the traditional design, PIA to carry up stairs or over things, long wheel base could cause chain to drag on curbs or otheobstaclesls you are lifting bike over, too much capacity, i.e. most people fill the space available and having 14,000+ cubic inches of capacity (assuming handlebar bag) is a LOT which in turn makes the bike more difficult to handle, tons of cyclists have already travel around the world without this system and the group is pretty independent so I would think if the design was needed it would have already been done, and the bike's components are most likely not designed for the extra weight so will fail much quicker.

I have toured with a tandem with full packs and if your bike would be anything like that, the handling is a PIA when only the rear is loaded as it can be wobbly.

Again, for design reasons, I would hit up the frame builders but for touring purposes, it just isn't needed.

The OP could easily cut that number down to almost nothing if he switched to dehydrated water and just make it as he needed it.



On a serious note at least more serious the OP seems to have the skills to manufacture and the inventive mind to go along with thinking big. I would encourage him to maybe even think more outside the box than he is though. He’s building on what is known and done with bicycle design and maybe he should be looking at something quite new and never done before. Starting with the bike and ending with the dual purpose cases. What if a frame came apart into many smaller parts with some new connection method that’s never been done like high tech tinker toys. And fit into some super light small cases that were water tight and made to attach to this knock down machine. Maybe water storage built into the cases and gear that fits in and around bike parts for shipping.

Or maybe the bike comes apart as you suggest, but it also makes up the framework of the cases. So instead of the hard cases being panniers, there's only rugged nylon left that folds another way to become more traditional panniers after you've taken the framework of the cases out and reassembled them to form the bike. Then you'd both have more room in the cases for stuff and you'e have some weight savings.

it did cross my mind

Seems like You know what You talking about
Thanx

I have to watch the Transformers movies again I think we are on to something here. If they can do it with a car, bus or fighter jet we can do it turning a bike into a suitcase.

So, were back to a folding bike, correct?

Maybe not so much folding as one that comes all apart and can be assembled in different ways like legos or tinker toys. Special lugs that have locks in them like couplers.

Maybe conversion number three would be a shelter.