Demystifying carbon joining techniques, types, etc

[weaponsgrade]

Anybody want to take a stab at this? What are the pros and cons of the different techniques to join carbon tubes together? Are most carbon tubes sourced from just a few handful of places or do some companies actually "make" their own tubes or have tubes specially made for them - similar to having steel tubing custom drawn. I'm trying to sort through the marketing speak and get a better idea of the technology out there. For example, every year Trek, Specialized, etc. seem to come up with some revolutionary carbon technique. On the other hand, Calfee doesn't seem to have changed his methods for the last 15 or so years. Is someone like Calfee really that far behind? or are the big production houses just spinning things?

[1centaur]

10 years ago Calfee was using a different supplier (MQC, the one Serotta bought) and is now apparently using Edge, as are Crumpton and Parlee, but each manufacturer specifies its tubing requirements differently, from what I am told. Trek was using MQC 10 years ago but presumably not now.

Giant and Time are famous for making their own tubes. Most tubes are Asian third party (some Giant, some not), and some Euro bikes even beyond Colnago's top end are supposed to use Euro sourced tubes. Regardless, there is plenty of ability to specify specific tubing differences in carbon land these days, and clearly a willingness among the makers to do so. CF manufacturing techniques also seems to be evolving fairly rapidly (different ways to reduce resin content; different ways to improve the inside quality of the tubes, e.g.).

Whether all the differentiation is leading to better bikes I will leave to others. I also hope pez or even Nick jumps in here with better knowledge of how much CF variation is going on.

[R2D2]

Don't forget designs like BMC that don't use tubes.

[sjbraun]

Does Look make their own CF tubes?

[wasfast]

Not sure about Look and their tube source. See the factory tour on Velonews.com:

http://velonews.competitor.com/2010/01/bikes-tech/tech-gallery-a-visit-to-look-cycles-in-nevers-france_102801

Time does weave from scratch:

http://velonews.competitor.com/2010/01/bikes-tech/time-for-a-visit-a-tour-of-the-time-frame-factory_102409

And since we're touring factories, don't forget Cyfac. I own a Tigre that I really like. probikekit.com is also offering excellent prices right now on the Gothica.

http://velonews.competitor.com/2010/02/bikes-tech/a-visit-to-cyfac_105077

[Charles M]

Much like the (stupid) generalizations made about different materials making "better" products by default, the same can very easily be done with regard to Carbon joining, tube manufacture and raw materials from fiber to resin...

Use all the best stuff in the wrong way and you still have a pile of crap. Use basic things very well and you can have a great bike. And lost in between.



Really to the point that I would say that no one method determines the quality of the bike.


Someone else with more time can clear it up, but most of the custom guys spec their own tubes...

Some guys make their own. It's BS to think that it's automatically better when you make your own versus having a very good fab place build to the spec you choose though.


As for build methods, most when done well are excellent.

Tube to tube, lugs and tubes, lugs and tube to tube combination, Insert fit using molded sections...


Not one single methid has proven to be "best".

Lugs sometimes get passed off as inferior, but tell that to Colnago, Parlee, Time, Look, Serotta etc... Better yet, ride incredible bikes from them and then say nay...

Insert fit from molded sections gets poopoo'd but I can tell you Trek are making some of the nicest production bikes period and they're doing it this way.

Monocoque gets tagged as an automatic advantage but...
Some folks dont realize that "monocoque" bikes are virtually NEVER mono... They should be called "quad" or quinta or sextacoque because they use molded sections joined in variable ways. The tube sections are a monocoque structure.

Mono shows a huge potential and some of these bikes are VERY good, but not automatically the best.

Tube to Tube have some thinking the joints might be weak, but well cut tubes joined with adhesive in the proper fashion will break under stress at the tube, not the joint. And when someone spec's the tube well and takes time to finish them properly, they rival and or beat the weight spec of most other formats. This process is being used in production bikes that tend to ride harsh and be very stiff, but that doesnt have to be the case either...


As for Tubes, there are a few ways to make em and there are great molded section tubes getting used in insert fit and tube to tube and lugged processes. Molded tubes and sections are getting really good. you can control shape and fiber orientation piece by piece, but not everyone using the process uses it to any place near it's full potential.

Wound tubes and roll wrapped also allow fiber choice and direction and again can be used to more or less of their potential.


There are advantages and disadvantages to all of these processes and raw materials really do matter and can make a significant ride and weight difference.

But it almost always comes down to the quality of the work more so than the potential of the process...

[AndrewS]

It seems to me that the difference in carbon "innovations" have really come down to how the tubes, joints, whatever are woven - ply direction and layering. Some makers advertise special types of fiber, but their bikes aren't 20% lighter or stiffer because of it.

Kestrel's old bikes were the only true monocoques I ever recall hearing about. It is not an easy thing to do.

Pretty much all carbon bikes - tube plies, joints, etc. - are held together with thermo-setting epoxy resin. There really haven't been any significant advances in these products for bicycles recently. It's the only thing that sticks well to carbon (as opposed to more ductile thermo plastics). I'm sure there is someone on the forum that can write a dissertation on the subject, but the real limitation on all these bikes is the epoxy. And all of these different joining techniques are ways of getting a strong enough bond between carbon layers or parts by having the right amount of resin and enough surface area.

Slip a tube into the correct sized lug and the cured joint shouldn't be much different than the those of the plies making up the tube. The carbon lug is an acknowledgment of this and an easier way to deal with carbon lay up than trying to make every part flow into each other. As long as the weight remains low, the end result is all about the same.


I think it is good to keep in mind that Vitus originally wanted to sell bonded 979 frame kits, not frames. They considered the task of bonding tubes to lugs with aerospace epoxy to be a simple enough that bike shops could do it. Bonding carbon to carbon is really not much different. The meat of carbon frame design is the lug areas where the tubes meet and stresses are highest. As long as those parts are strong enough the frame is likely to work.

[eddief]

if ya scroll down to "the making of" video.

kinda a mind blower about the differences between the steel craft and the carbon craft. highly engineered cookie cutting.

http://www.gurubikes.com/enUS/products/photon/

[sg8357]

Buy a tube of JB Weld and have at it, you too can be a frame builder...

http://www.bringheli.com/dcs.htm