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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 10-04-07, 05:30 PM   #1
zonatandem
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Lighter/stronger/cheaper than carbon fiber?

Don't be looking for it in the next couple years in your favorite bike shop . . .
However, got a heads-up from Bob Davis @ Zona Tandems about a new material that is being tested.
Currently being evaluated in the city of Delft, in The Netherlands, is an aluminum based composite called CentrAl.
This alu/composite is stronger, lighter and less expensive to make than carbon fiber.
Bob spent years in the aerospace industry and keeps his finger on the pulse on what is being developed.
CentrAl alu/composite is apparently 'immune to metal fatigue' and is being tested for use in aircraft.
GTM Advanced Structures, a Dutch company, is behind the development of the Central Re-Inforced Aluminum project.
Like many other things that started in the aerospace industry, eventually it could filter down and we could be riding an uber-tandem made of this new composite.
So, the future looks brighter and lighter!
Pedal on TWOgether!
Rudy and Kay/zonatandem
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Old 10-04-07, 07:02 PM   #2
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I wonder how much cheaper it could be compare to carbon fiber composite.
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Old 10-04-07, 07:18 PM   #3
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But does it ride like Aluminum (Bad) or CF (Good)?
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Old 10-04-07, 08:24 PM   #4
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Originally Posted by joe@vwvortex View Post
But does it ride like Aluminum (Bad) or CF (Good)?
I think you meant:

But does it ride like Steel (Good), Aluminum (Bad), or CF (Bad)?



Sheldon
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Old 10-04-07, 09:33 PM   #5
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Have ridden/owned steel, alu, ti and c/f singles and tandems.
All are good and have their merits; however, our butts are on a carbon fiber tandem.
Just our experience/opinion/choice.
There is no mention of how much cheaper their CentrAl would be, but said it could save billions (with a 'B'!) in the aerospace industry. Weight is 20% less than carbon fiber.
Most of their info is in Dutch and/or English.
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Old 10-05-07, 05:07 AM   #6
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By God, there may be hope for the Dutch after all.

I wonder which of these three materials leave the lightest footprints on the environment. Are carbon gizmos actually carbon sinks?

If we knew what we were doing, it wouldn't be called research would it?
A. Einstein
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Old 10-05-07, 05:55 AM   #7
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I always appreciate the way Rudy responds to questions on this forum. He is never judgmental and displays a great deal of knowledge and seems to always be looking for ways to promote unity in the world of cycling. It dosen't matter if you are riding a $10,000.00 tandem or some garage sale one that you are glad to have to share with your family, Rudy will have an encouraging word and always good advice to offer.
Thank-you Zonatandem for all that you do and say!
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Old 10-05-07, 07:00 AM   #8
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FWIW: here's a story: http://www.tgdaily.com/content/view/34052/113/

Looks promising.
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Old 10-05-07, 07:15 AM   #9
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Originally Posted by Lonnie Seachris View Post
I always appreciate the way Rudy responds to questions on this forum. He is never judgmental and displays a great deal of knowledge and seems to always be looking for ways to promote unity in the world of cycling.
Yes, ZonaT is a very great man -- truly one of the saints of the cycling world. I just wish he could write in complete sentences and paragraphs instead of the biblical shorthand we've come to know and love.
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Old 10-05-07, 07:45 AM   #10
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I guess I'm more facinated with how this "story" has spread throughout the net than any potential benefit to bicycle frame design. After all, there are already several metal matrix composite (MMC) frames available today and they are, at best, even more rare than Calfee, ariZona, or ZXT carbon composite tandem frames, e.g., Griffen's MMC and Vyatech's IsoGrid & ExoGrid materials used by Santana (as well as two companies owned by Vyatech: Titus, and Maxim).

Moreover, if I understand how and where this new technology would be used, it's primary application is wing skins, stiffners, longerons, and other flat panel or geometric shapes that bring to mind the I-Beam magnesium frames. Perhaps it can be extruded or shaped into tubes as well, that's just not how I've seen CFRP technologies used.

However, getting back to the "story", it appears to me to be a press release coming out of technical conference in Delft that was picked up and distributed by UPI and a few other outlets like TG Daily's (no relationship) Rick Hodgen, who seems to be everywhere in the world covering and embellishing upon every subject known to mankind -- at least based on a quick Google new search. (http://news.google.com/news?client=s...=1&sa=N&tab=wn). Given the investment made by Boeing and others in CFRP technologies and manufacturing capabilities, this latest MMC looks like it has a steep hill to climb and the press release is more or less a very effective tool for getting the word on the street that a firm is looking for capital to fund further research.

Anyway, here's the REAL scoop that I'm amazed no one picked up that ALSO came out of Delft last week:

Quote:
Originally Posted by Science News
Scientists discover how bicycles work
By UPI
Sep 24, 2007, 17:56 GMT


DELFT, Netherlands (UPI) -- Dutch-led researchers have solved a nearly 150-year-old mystery by determining how a moving bicycle can be as stable as it is.

Delft University of Technology researchers, working with colleagues from Cornell University and the University of Nottingham, have created the ultimate model of the bicycle.

'Bicycle manufacturers have never been able to say precisely how a bicycle works,' said Arend Schwab of Delft`s Faculty of Mechanical, Maritime and Materials Engineering. 'They have always had to refine their designs purely through experimentation.

'In our model, they can enter into the computer all of the various factors that influence the stability and handling of their bicycle,' said Schwab. 'The model then calculates how the bicycle will react at specific speeds.'

The study that included researchers Arend Schwab and Jodi Kooijman appeared recently in the Proceedings of the Royal Society Series A.

Copyright 2007 by United Press International
Hang on to your hats and your wallets, the next latest-and-greatest innovations in bicycle design are just around the corner! Yeah, right... Which is why I previously posted my retrospective on bicycle technology from the 1800's: Bicycles & Tandems: A Historical Retrospective. Everything old is new again, and much of what is new isn't necessarily improved...

Hell, it's taken me 5 years to come to a decision regarding carbon as a tandem frame material and it's still a leap of faith, despite 10 years and 200+ examples of carbon-framed tandems being in use around the world.

Last edited by TandemGeek; 10-05-07 at 12:26 PM.
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Old 10-05-07, 02:06 PM   #11
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Quote:
Originally Posted by stokessd View Post
I think you meant:

But does it ride like Steel (Good), Aluminum (Bad), or CF (Bad)?



Sheldon

As someone who's ridden NOTHING but steel road bikes since 1973 I'm as big a steel "guy" as the next. However - I did switch to a CF roadbike two years ago and there's simply nothing that steel does better IMO. Yes - there is something special with the ride of a steel bike - but quite frankly - the weight and flex penalties that you pay don't outweigh the benefits. We currently ride a CoMo steel tandem - and we'll be going CF when the time comes that we can afford it.
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Old 10-05-07, 03:13 PM   #12
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It looks to me like this material is a combination of aluminum and Carbon Fiber Composites. Carbon fiber composites have a density of roughly .06 lbs./in^3, and aluminum is roughly .10 lbs./in^3. Also, carbon fiber is stiffer than aluminum in the direction of the fiber. Aluminum is tougher and more impact resistant than CF composites, and has the same mechanical properties in all directions - though lower than the directional properties of CF composites.

In aerospace, there are applications which would benefit from an efficient combination of the properties of both materials. Aluminum could be directionally stiffened and made to be more fatigue resistant by CF composites and the added toughness and isotropic nature of aluminum could benifit certain composite structures... As already mentioned in another post, panel structures and wing skins seem like great candidates for a material like this. I don't see a real benifit for most tubular structures, like bicycle frames.

As for the claims of lighter and cheaper, a lot of that may be misunderstanding by the media. As aluminum is higher in density than carbon fiber composite, and has lower stiffness and tensile strength, I don't see how combining it with a CF composite can make a lighter structure, unless it provides properties which allow thinner skins to be used in foam or honeycomb panel type structures, which don't really apply to bicycles. Cheaper? If less carbon fiber can be used in a given structure, and replaced with aluminum, aluminum is a cheaper material. But then the processing costs to efficiently combine the materials should bring the cost back up.

Metal matrix composites (carbon fiber in metal rather than epoxy) have been desired for a long time, especially if they could be reinforced with continuous carbon fiber, but uninsulated carbon fiber in contact with a bare metal greats a galvanic reaction the corrodes the metal fairly fast. This was a big problem when carbon fiber first hit the boating industry where if it was in contact with seawater, even a stainless propellor would be gone pretty quick. The metal matrix composite (MMC) described in the post above is aluminum with short ceramic, not carbon, fibers within the metal. The short fibers make it a bit stiffer than aluminum alone, but doesn't approach what could be done if continuous carbon fiber could efficiently be combined with aluminum as the matrix instead of epoxy. I think this company is just sandwiching sheets of aluminum with sheets of carbon fiber composites.

Sorry this post got a bit long, but don't hold your breath waiting for any new material to be used in bicycles that is lighter, cheaper and stronger than carbon fiber. Carbon fiber itself, meaning the raw material, has also actually increased significantly in price over the last few years due to an increased worldwide demand. The manufacturers are increasing their supply capacities, but I don't expect any price relief for quite a while...

Jim
(President - Advanced Composite Products and Technology Inc. (ACPT))
Oh yeah - and riding steel
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Old 10-05-07, 05:51 PM   #13
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The metal matrix composite (MMC) described in the post above is aluminum with short ceramic, not carbon, fibers within the metal.
A noteworthy point and, to be frank, I'm not even sure the boron carbide particles could could be classified as a fiber by the time everything is reduced to something that resembles Nestle's Quik.

For those who are interested, here's Griffen's description of their MMC...

Quote:
Originally Posted by griffenbikes.com
In the late sixties, the government gave UCLA research labs a grant to develop a material that would replace aluminum. The material needed to be stiffer and stronger than aluminum, lighter than aluminum with no fatigue life. To achieve these results they developed a material - boron carbide ceramic metal matrix. They used boron carbide, the hardest known material next to a diamond. When boron carbide is mixed with aluminum it significantly strengthens and stiffens the aluminum. They also developed a process to make this new material. The process yielded a mechanical bond vs. a chemical bond, which is most commonly used. They mechanically combined aluminum, boron carbide, titanium, nickel zinc and copper. They reduced all elements to a 4 micron dust and then mixed them in a jet mill. This provided a homogeneous mixture of all the elements. They then compressed this mixture using a cold isostatic press to form a powder billet. They made various components from the billet, e.g., seats for the Apache helicopter. Griffen takes the billet and extrudes it to make tubing.
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Old 10-06-07, 09:57 AM   #14
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Am not an engineer of any type, but do have a keen interest in tandems/bicycles.
Have seen and hefted MMC (Grifffen), magnesium (Paketa) and bamboo (Calfee) 0 tandems, but have not yet ridden one.
Have ridden dozens of brands/models of tandems. Some were great, some not so great. While tandem design/ideas have not radically changed since the late 1890s we'd rather be riding one of the newer re-incarnations than the early ones.
Suspension, adjustable saddle/stoker and pilot stems, eccentrics, cross-over drive, laterals, no-laterals all have come and gone and re-appeared again. This time newer materials, whether metal or non-metal, are the big change in our 2-seaters and what is driving the market/sales.
Thought it would be worthwhile mentioning the GTM Advanced stuctures CentrAl. Have read most of their website in English and Dutch (am relatively fluent in both) and they do imply some great things . . . however all their ideas are still being tested/evaluated. Will it be applicable to tandems/components?
'Steel is real' has been the mantra for decades. Non-heat treated alu had been used but was quite flexy. Then Cannondale presented heat-treated aluminum and that took a bite out of the steel market. That was followed by titanium, magnesium, carbon fiber and bamboo or combinations of various metals/non-metals.
As stated earlier, have ridden steel, alu, ti, c/f , Isogrid, lateral/lat-less twicers, etc.
If it wasn't for someone inventing matches, we'd still be rubbing two sticks together to make fire.
We all have our preferences and fortunately there's lots of choices out there!
Put your $$ and butts on what your team prefers!
Pedal on TWOgether!
Rudy and Kay/zonatandem
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Old 10-06-07, 02:14 PM   #15
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Thought it would be worthwhile mentioning the GTM Advanced stuctures CentrAl.
It was worthwhile and interesting, no question about it.

Again, it's just interesting to see how one press release coming out of Delft that pertained to advanced materials for aerospace gained traction whereas another that reports the development of a computer program that can purportedly explain and model the heretofore not fully understood physics that underly bicycle stability and handling went unnoticed. By unnoticed, I mean you won't find any mention of it anywhere in the BikeForums. In fact, the only place I've seen it mentioned is in the very obscure rec.bicycle.tech forums.

Like you, I really don't care what tandem brand, model or material anyone choses to ride: ride what you like and like what you ride has always been my mantra.
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Old 03-19-08, 06:45 AM   #16
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sorry to revive this thread...
i saw this add in the Toronto Craigslist http://toronto.craigslist.ca/tor/bik/610738167.html
i wonder if this is an application of the technology mentioned above?
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Old 03-19-08, 08:10 AM   #17
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I think it is a manufacturers name and not the MMC material mentioned above. It would be interesting to contact the seller and see what details he comes up with to justify 4500. It reads like a vintage Alan Carbon bike (aluminum lugs with bonded carbon tubes).
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Old 03-19-08, 08:32 AM   #18
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I don't know squat about this company, but it reminds me of another enterprise that operated out of the Great White North that initiated the flow of low-ball priced titanium tandem frames from Asia with knock-off couplers of a few years ago.... only this time the offering is a knock-off of Santana's Beyond and Dual-Moto frame designs.

Yes, I'm being a bit of a protectionist...
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Old 03-19-08, 04:09 PM   #19
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Yes, I'm being a bit of a protectionist...
There is nothing wrong with that.
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Old 03-20-08, 10:54 PM   #20
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hope for the dutchmen?.. i think so

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Originally Posted by rjberner View Post
By God, there may be hope for the Dutch after all.

I wonder which of these three materials leave the lightest footprints on the environment. Are carbon gizmos actually carbon sinks?

If we knew what we were doing, it wouldn't be called research would it?
A. Einstein
great hope!
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Old 03-20-08, 10:54 PM   #21
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We've always discussed tandem face-to-face with the builder . . . have never been disappointed with the results!
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Old 03-20-08, 10:58 PM   #22
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There's more than 'hope for the Dutch': they perfected building of dikes centuries ago and reclaimed land from the North Sea . . . bit better than what was built in New Orleans!
Tandem content: yes, the Dutch even build tandems!
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Old 03-24-08, 12:18 PM   #23
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*******

you are one you ****
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Old 03-24-08, 02:13 PM   #24
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btw, i never got a reply from the seller.
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