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In the prospect of what will be a semi-long-term search for a new frame, one opportunity came up where I can have a custom layup done on an existing mold. While I'd leave it to the frame builder to decide what carbon goes where, I am just searching for a little "general" knowledge on some things.
First, what is the difference between T800 and T1000 carbon weaves?
T1000 is lighter, but by how much? If a full frame goes from 100% T800 to 100% T1000, what would be the difference, approximately, for a frame in a typical 54 geometry? T1000 (sometimes called "hi mod", no?) not only has greater tensil strength, but it's also more fragile...
Not that it can be put into a full description, but how much more fragile would it (a T1000 frame) be compared to the T800?
... and, finally, if a person were to have those two options available, T800 and T1000, and and they were the builder of the frame, where would you put certain weaves in the frame? For example, T800 in the seat tube and seatstays, T1000 in the chain stays? Downtube? Headtubes? Junctures? Top Tube?
Is mixing them together possible, or how much more complicated does it make the building of the frame?
Certainly a mfg like Rolo (and others) laser cut specific shapes in specific weaves and integrate many options into one frame...
Anyway, just thinking a bit about this, and maybe some knowledge can be shared if you have any to offer on this. It would be very much appreciated!
First of all the density is the same for both. You could however conceivably make a lighter bike with T1000 due to its higher tensile strength and modulus. Quite simply a T1000 frame would theoretically be stiffer and stronger than aT700 frame.
But the layup needs to be optimised to the material!
The fragility of the frame is highly dependent on the resin system used and also the skill and care of the layup (no preheating of the prepreg before the autoclave) etc and of course the lay-up schedule or plybook is of paramount importance.
The table below is from our website and shows the materials properties as composites with a given resin system.
Please note that a as a composite the material has almost half the modulus compared to the raw fiber. Twill will also have a tensile modulus of about 50% of UD.
As a side note I'd also like to mention that outside the bike industry neither T700 nor T1000 are considered as UHM or even HM materials.
The 'T' in T1000 is Torayca's designation for high Tensile strength; high Modulus materials have the designation 'M', as in M46J or M55J.
According to the Japan Carbon Fiber Manufacturers Association classification T1000 is actually at the low end of the intermediate modulus fibre range and M55J is at the very high end of the high modulus range.
Please PM me for a more in-depth discussion if you want.
EDIT> Data sheets for T800 & T1000 plus JCFMA classification link.
Can't remember the source of this info, but it also mentioned that most manufacturers boosting "full 100% T1000 layup" in their ads were probably lying. I want to remember that it might have been an editorial answer in some magazines reader's questions section. Anyway, is it just BS and myth?
Stiffer is stiffer stronger is stronger and more expensive is more expensive. But yes, the more exotic the material the more care you need to take with the engineering, handling of the material, resin system, plybook/layup, vacuum systems, molds, autoclave temp ramping and general craftmanship.
It's all pretty straightforward really, even in the bike industry..
Ride quality is a potential factor too.
But at days end the layup pattern can (and almost always does) dictate more of the weight, stiffness, ride quality and durability than the carbon used.
You can make a pretty great bike or a P.O.S. out of either or both materials.
There is a new fiber (along with with a corresponding resin system) coming from Toray, T1100, that will be/is even stronger but it's not widely available yet.
So no, limiting the use of T1000 from a strength perspective makes absolutely no sense!
Limiting it from an economic perspective makes absolute and total sense! Again just look at the chart above...
Yes UHM fibers are more brittle but T1000 is not a UHM fiber! It is, like I pointed out above, a high strength fiber.
BUT you need to match the resin system to the fiber! Or more specifically every fiber brand/type has specific surface properties that you need to match the resin system to.
There has been some problems in the aviation industry reported with the toughness of both T800 and T1000 prepreg but that had to do with the matching of the resin system.
Correct matching of the resin system is of paramount importance.
There are resin systems that will create a stiffer tube with a given fiber but it will be less tough than a less stiff but tougher resin.
You have to look at the combined performance of the resin-fiber system.
Edited w link to Toray
Edit - the new Mitsubishi Pyrofil MR70 intermediate modulus fiber claims a strength over 7GPa and would then be beating the T1100G (dream carbon in the Dogma F8) for stiffness.
Are the resin systems made by the same companies that make the carbon, or is there a big third party element involved?
I am very interested in this area, so I am going ask you a load of questions; if you can't be bothered to answer, or whatever, just tell me to shut up!
-Pre-pregnation; any chance you could explain how you go about choosing what is the correct one for a particular carbon? I know you said that it needs to be matched to the specific surface properties, but any chance you could expand on this? Are there any common pre-preg/ carbon combinations that are 'go to' mixes that work well, or is everything bespoke?
-I suspect that cycling manufacturers will piggy-back on the discoveries of larger industries, regarding carbon, but are there any peculiarities with the requirements of bicycle parts, which need original design / manufacture of carbon?
Again, nice one for your replies in this thread. Excellently interesting and useful.
... without hijacking the thread - I also have a few quick questions regarding manufacturers that choose to weave their own fibre and have their own resin systems before laying up the frames (Giant do this now, I believe Time does too, or used to).
These companies (Giant in this example) still claim to be using T800 carbon fibre, which is a Toray product, yet are weaving themselves and using their own resin systems - does this mean that the final quality and/or properties of the carbon they use can be very different from another manufacturer who uses pre-preg, pre-woven sheets? In other words, T800 'aint necessarily T800?
In the example of a pre-preg, pre-woven sheet - do Toray for example:
a) weave the fibre and then impregnate with the resin before shipping to bicycle manufacturers, or;
b) do they supply pre-woven sheets to 'a mid step company' who apply the resin and then ship to the bicycle manufacturers, or;
b) do Toray supply spools of fibre to 'a mid step company' who weave and apply resin to the carbon before they then ship to bicycle companies for use?
With regards to finding the best pre-pregger and system it's really down to putting the nose to grindstone. We have used these guys in the past:
https://www.cytec.com/businesses/aerosp ... egs-resins
Since then we have moved on to a smaller prepregger. We are lucky to work with some very skilled carbon engineers with good contacts at german universities that are at the forefront of this kind of stuff. Cytec was the supplier for the UKSI bikes that you saw Pendelton, Wiggins and Cav use at the olympics. They certainly know their stuff! They chose a different and tougher resin system we had used in our first prototypes and since we had a very stiff layup we could improve on both the ride quality and the toughness of the bike by changing to the less stiff but tougher resin.
So yes, T800 can and will have pretty different properties depending on the resin system used. Also the handling of the material (pre pregs need to be stored in freezers and starts to cure at slightly over room temperature) will greatly affect the final properties. For all you tube to tube fanatics: The glue used at the joints has a dramatically lower modulus than f.i. the T800. This creates a stress raiser at the joint,where the relatively soft glue meets the stiff carbon, this is one of the reasons some people's T1000 bikes fail..!! Thus the myth and folklore of T1000 being brittle is propagated. Sorry, could not help myself:)
Really serious companies fabricate their own test samples of prepreg sheets and test them rather than rely on manufacturers data. This summer we plan to such tests at the university of Würtzburg in order to further understand this issue and be able to plug in even more correct data into the FEA. (Something Kate our FEA expert and layup optimizer who has most of her background in aerospace has asked us to do all along.)
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