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  1. #51
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    Quote Originally Posted by Maelochs View Post
    How is a welded pyramid of titanium stronger than five times as much titanium scrap in a plastic bag?

    How is an X-braceds rectangle of steel tubes just as strong yet much lighter that a rectangular steel slab of the same perimeter dimensions?

    Oi.

    If you do not reject the answer while asking the question you might figure it out for yourself.

    A frame can be made lighter and use less material by using the material more judiciously.

    The folks at say Trek (not that they would know anything about engineering or constructing CF bike frames that You don't know better, right?) started working with CF a few decades ago. They learned a lot about its properties, its uses, its strengthts and weaknesses.

    Aerospace and performance vehicles of all sorts have been using CF for even longer. There has been literally decades of research into the material---and this research is Ongoing.

    So Trek (as an example) looks at what has been learned by the decades or materials science research, and figures out, "If we use an internal bladder inside the external mold we can get better impregnation and distribution of epoxy, and control the thickness of the piece at every point. If we carefully align the fibers in different directions and thicknesses, we can create parts which are springy in one direction and very rigid in others. By bonding together these different parts, we can achieve greater compliance where we want it, greater rigidity where we want it, and use less material overall because we only put exactly what we need at each exact spot to do exactly what we want."

    Are you with me so far?

    That 1200-gram frame might have had tubes of basically the same thickness with all the plies laid in the same direction. To get greater stiffness, the engineers simply used more layers of cloth, and more epoxy, which meant greater weight. And, because the resulting frame was very rigid, it had to be even more rigid---more overbuilt---because it could not dissipate energy by flexing, but had to absorb that energy through more material.

    Still following?

    Consider a disc wheel. Say your bicycle has a steel disc for a wheel. It is grooved along the outer circumference to accept a tire and pierced at the center to accept an axle. It wights hundreds of pounds because it is a solid steel disc 26 inches in diameter and an inch wide.

    I come along and make a thin steel strap and bend it into a hoop, and take a bunch of steel wires and attach them to the hoop and to a tiny little steel cylinder which is pierced to take an axle. Voila. I have produced a spoked wheel which weighs perhaps two pounds and is just as strong as that steel disc in all the load ranges which matter for the given application.

    Still on the same page?

    Using less of the same material but using it more cleverly, I have drastically reduced the weight of the product while still producing a product more than sufficiently strong to perfrom in the ways it is intended.

    Got it? Seems actually pretty basic ... in fact glaringly obvious to anybody bold enough to actually look.



    crit_boy might seem to be a little harsh here, but what he says is right on. If you Know you don't know something, admit that. Don't sit around telling everyone a thing cannot be a certain way because you cannot understand it. Ask, learn ...

    Think about it ... when you go to a doctor, do you debate with the doctor? S/he has years of schooling, years more of real-world experience, and you are experiencing something you don't understand or you wouldn't be there. If the doctor says, "I did all the relevant tests and my diagnosis is this" do you tell the doctor "I have never heard of that condition, therefore you must be wrong"?

    Maybe you do. And if you get a second and a third opinion and they are all exactly the same, are you going to ignore all the doctors ... because you have not bothered to do the slightest bit of research yourself?

    I hate to say it, but the best way to not seem really silly in debates like this is to not debate what you Know you don't know. I hate to say it ... because that is what you have been doing.

    All you would really need to do is look how the major manufacturers have been producing lighter and lighter CF frames ... with no increase in failures. Pretty obviously they have found a way to do it ... because they are doing it. You might not understand the science, but you can actually see the freaking bikes. You might even own one. How much more real does it need to be?

    Similarly, you could look at how steel bikes have also come down in weight over the last several decades. if CF freaks you out ... how have constructors managed to produce steel-framed bikes which are vastly lighter and also stronger than the old 42-lb Schwinns of yesteryear?

    Again, you might not understand the science ... but somehow you can buy steel bikes which weigh under 20 pounds, and as for strength ... they last forever. According to you, that simply isn't possible ... but the bikes are there.

    A good way to tell if you cannot understand something and maybe should do some research before you shoot your mouth off, is if your version of "reality" precludes the existence of things which very much do exist in the reality you share with everyone else.

    if your "idea" tells you that stuff cannot exist, which your senses tell you does exist ... maybe you have the wrong idea.
    I think get what you're saying. But it appears that what you're saying is how to make a 1200g CF frame into a 700g frame while still maintaining its strength and stiffness by using and/or manipuating these criteria:
    1. layup technique
    2. compaction technique
    3. construction technique
    ...and
    4. I will also throw in different fiber type (which you didn't mention in your post).

    But that was not my question. My question was along the line that if I apply the SAME techniques and material to a 1200g frame, then wouldn't the 1200g frame still be stronger then the 700g frame?

    As for the argument that the 700g frame "meets design spec and intended use", well, this will depend on what is the acceptable level of intended use and failure, but this is more for the warranty statistician to figure out since manufacturers need to make sure they don't lose money on warranty, which ties into the business decision making process. However, I'm mainly interested in the science, not the business of warranty statistic.

  2. #52
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    Quote Originally Posted by aclinjury View Post
    I think get what you're saying. But it appears that what you're saying is how to make a 1200g CF frame into a 700g frame while still maintaining its strength and stiffness by using and/or manipuating these criteria:
    1. layup technique
    2. compaction technique
    3. construction technique
    ...and
    4. I will also throw in different fiber type (which you didn't mention in your post).

    But that was not my question. My question was along the line that if I apply the SAME techniques and material to a 1200g frame, then wouldn't the 1200g frame still be stronger then the 700g frame?

    As for the argument that the 700g frame "meets design spec and intended use", well, this will depend on what is the acceptable level of intended use and failure, but this is more for the warranty statistician to figure out since manufacturers need to make sure they don't lose money on warranty, which ties into the business decision making process. However, I'm mainly interested in the science, not the business of warranty statistic.
    Nope, you missed the whole point of the response.

    In summary - just because you don't understand does not make it false or impossible. The light frames exist. The fact that you don't understand how to make them, does not alter the reality that they exist. Kind of like global warming.
    Last edited by crit_boy; 10-19-2017 at 07:04 PM.

  3. #53
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    Quote Originally Posted by crit_boy View Post
    Nope, you missed the whole point of the response.

    In summary - just because you don't understand does not make it false or impossible. The light frames exist. The fact that you don't understand how to make them, does not alter the reality that they exist. Kind of like global warming.
    you talk too much, with little info. You're not even attempting to discourse, but good at deflection. Go seek a mirror.

  4. #54
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    Not sure where my deflection or lack of discourse was. But, i note your deflection with a personal attack.

    FWIW, I did provide an answer to the OP question. You have decided to derail the thread in a completely different direction.

    Your question cannot be definitively answered.

    Is there a combination of layup, fibers, and resins where a 700 g frame is stronger than a 1200 g frame - depends on the particular layup, fibers, and resins.

    Is there a combination of layup, fibers, and resins where a 1200 g frame is stronger than a 700 g frame - depends on the particular layup, fibers, and resins.

    Also depends upon your definition of the word "stronger". Strong has different meaning in different contexts. It is not defined with a single value in all circumstances. As an example, distance has a single measure - regardless of the units to define it - distance is the space between two points. However, strength means different things in different arenas (Charpy fixed energy, shear strength, compression strength, etc.)

    If you want to take it to a more basic level:
    -Is here a situation in which a steel shape can be stronger with the use of less material?
    Yes, for the transmission of torque a hollow shaft is stronger than the same diameter solid shaft made with the same material.

    How about bike things: Double butted spokes are stronger and lighter than straight gauge spokes.

    -Is here a situation in which a steel shape can be weaker with the use of the same amount of material?
    Yes, a sheet aluminum foil is weaker than the ingot from which it was rolled.

    Now that we know an empirical examples of things that are lighter and stronger; and something that is weaker with the same amount of material, can we move on from the baseless pontifications concerning carbon fiber frame design.
    Last edited by crit_boy; 10-20-2017 at 09:18 AM.

  5. #55
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    Quote Originally Posted by crit_boy View Post
    Not sure where my deflection or lack of discourse was. But, i note your deflection with a personal attack.

    FWIW, I did provide an answer to the OP question. You have decided to derail the thread in a completely different direction.

    Your question cannot be definitively answered.

    Is there a combination of layup, fibers, and resins where a 700 g frame is stronger than a 1200 g frame - depends on the particular layup, fibers, and resins.

    Is there a combination of layup, fibers, and resins where a 1200 g frame is stronger than a 700 g frame - depends on the particular layup, fibers, and resins.

    Also depends upon your definition of the word "stronger". Strong has different meaning in different contexts. It is not defined with a single value in all circumstances. As an example, distance has a single measure - regardless of the units to define it - distance is the space between two points. However, strength means different things in different arenas (Charpy fixed energy, shear strength, compression strength, etc.)

    If you want to take it to a more basic level:
    -Is here a situation in which a steel shape can be stronger with the use of less material?
    Yes, for the transmission of torque a hollow shaft is stronger than the same diameter solid shaft made with the same material.

    How about bike things: Double butted spokes are stronger and lighter than straight gauge spokes.

    -Is here a situation in which a steel shape can be weaker with the use of the same amount of material?
    Yes, a sheet aluminum foil is weaker than the ingot from which it was rolled.

    Now that we know an empirical examples of things that are lighter and stronger; and something that is weaker with the same amount of material, can we move on from the baseless pontifications concerning carbon fiber frame design.
    depends.. depends... depends... how about give specific details. What's layup schedule? Compaction process? or whatever process? What fiber type? How about crosslink within fiber layers? And oh yea, anything material and processes used on the 700g frame can be used on the 1200g, yet you claim the 700g can be made stronger. You made the claim, so you need to explain. "It depends" is not going to cut it in a technical discussion.

    So far, your argument revolves around the thesis that "any technical explanation will be too hard for anyone in here to grasp, so people in here shouldn't ask for one, and shouldn't pontificate about one either, and instead just accept your non-technical explanation that things are true like you say". Yeah, real strong argument there. I guess that settles it.

  6. #56
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    Quote Originally Posted by Steve B. View Post
    BS

    Do you maybe want to list some examples of folks who’ve died when their Chinese carbon exploded ?
    +1.......I have to agree that this is BS. A lifetime warranty is no indicator that one is better than another. So you can't look inside the frame. the issue with non-branded frames is that it can be hit or miss, but a hit might actually be better than a name brand frame.

    When cyclists say Chinese carbon, does that also apply to Taiwan? I wonder how many people have actually died from these open mold frames. When I see failed frame photos, they are usually reputable brands; when I hear of people actually suffering serious injury or death, it is usual big brand frames as well. For what it's worth, Taiwan does carbon fiber better than anywhere else in the world. Governments all over the world look to Taiwan (including the US) to provide for their military needs of carbon. A fly by night company anywhere, is a gamble. Everything is hearsay to justify why we pay more. It makes us feel good. We wanna look pro even if we will never be. Heck most won't even try racing at all. My SS EVO Hi Mod is an awesome bike, but I bet I can get a Hung Fu frame that might be close to the Evo's weight, and will be just as durable and offer me just as much enjoyment. A good frame is a frame that is well engineered. With a carbon bike, we don't know what that is. We place our faith in the marketing department of a bike companies whose job is to sell bikes.

    As for science behind carbon's strength to weight ratio is founded and it's second to none, but it's not the whole truth. Carbon is unidirectional, so the max strength is in one direction. That direction is for efficient power delivery, which is usually tops. However, it also bring out carbon's weakness: Impact resistance. This unidirectional strength is the reason they don't make carbon fiber touring bikes. To make them that strong, the bike would likely weigh what a Columbus Spirit frame weighs, which is still light.

    To the OP: I have two carbon bikes (soon to be one), and two aluminum bikes (soon to be three). I'm selling my Cannondale SS EVO Hi Mod to buy a CAAD12 Black Inc. Nothing wrong with carbon, but I prefer aluminum for crit racing. Aluminum has a much better chance of surviving a crash than a carbon frame. I wouldn't say one material is better than another; They all have their merits and shortcomings. then there are differences amongst bikes of the same material. Not all aluminum is rough riding and not all carbon is comfortable riding. You ride aluminum now and you're curious about carbon. Carbon is a fantastic material, but so is aluminum, steel and titanium. It's a matter of preference. Frame performance and comfort isn't based on material; It's based on the builders intentions when they built it. A Cannondale CAAD12 and Specialized Allez are very comfortable aluminum race machines. As for steel, a buddy of mine has a 16 lb. steel Fairdale Goodship with pedals. I doubt anyone is going to scoff at any 16 lb bike.

  7. #57
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    The OP wasn't asking for a primer on materials science. The answer to his question is that a decent carbon frame (one made in a factory that has some quality control) will last as long as he wants to keep riding it. I have carbon frames in my shop going back to a 1991 Look. I stopped riding it not because it had anything wrong with it but because new technology made it obsolete. I moved on to a bunch of other frames, all replaced by newer iterations of technology - lighter, more aero, etc.

    All frames can break due to a crash or some sort of accident. Carbon is probably the easiest to repair and can be typically repaired back to at least it's original strength, if not stronger.

    Amanda Coker puts more miles on her carbon frames in a year than most people do in a decade - so far, I haven't heard of a single carbon frame spontaneously exploding on her...

  8. #58
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    Quote Originally Posted by terbennett View Post
    +1.......I have to agree that this is BS. A lifetime warranty is no indicator that one is better than another. So you can't look inside the frame. the issue with non-branded frames is that it can be hit or miss, but a hit might actually be better than a name brand frame.

    When cyclists say Chinese carbon, does that also apply to Taiwan? I wonder how many people have actually died from these open mold frames. When I see failed frame photos, they are usually reputable brands; when I hear of people actually suffering serious injury or death, it is usual big brand frames as well. For what it's worth, Taiwan does carbon fiber better than anywhere else in the world.
    So you are really proving my point. If a no-name brand can be hit or miss, are you really willing to play Russian roulette in order to get a too-goo-to-be-true price?

    I am not arguing that Taiwanese and Chinese carbon frames can't be good. Heck, how many carbon bike frames are there that AREN'T made in China or Taiwan? But regardless of where it's made, I will trust a known name brand regardless of where it's made before I will trust a no-name fly-by-night brand whose QC is unknown.


    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
    -- Warren Buffett

    "Education is what you get when you read the fine print. Experience is what you get when you don't. -- Pete Seeger



  9. #59
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    Quote Originally Posted by Lombard View Post
    I will trust a known name brand regardless of where it's made before I will trust a no-name fly-by-night brand whose QC is unknown.
    Good lord, people how hard is it to figure this stuff out????


    If you don't want to buy Chinese CF, DON'T.

    It is not a difficult concept.

    The fewer people buy them, the lower the price, the more I can afford. Do everyone a favor and stick by that stand.

  10. #60
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    Quote Originally Posted by Maelochs View Post
    If you don't want to buy Chinese CF, DON'T.
    What of I don't want disc brakes either? Should I buy those or no?

  11. #61
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    2006 Alan Carbon Cross. Still does what it was built to do.

  12. #62
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    " Nothing wrong with carbon, but I prefer aluminum for crit racing. Aluminum has a much better chance of surviving a crash than a carbon frame."

    This is a generalization that is not necessarily true. Aluminum may stand up to a side impact better, but not a frontal impact where the aluminum frame is likely to crumple whereas a carbon frame is likely to flex and take no damage whatsoever.

    This is why I agree with those who say that you can't generalize the longevity of any frame based upon the material from which it is made. There are far too many factors involved in the equation to just peremptorily claim that one is unsafe for long term use.
    Life is short... enjoy the ride.

  13. #63
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    Not sure why these discussions tend to devolve into the "either/or" paradigm rather than the "both, and..."

    Yeah- the more you understand about frame-building, the more you recognize the truth of 'it's not what you use, it's the way that you use it!'
    That said, let me steer towards the autobiographical and mention that...

    I have a Carbon Fiber 'Endurance Geometry' bike, an Aluminum Alloy 'Sporty' bike, and a 4+ decade old 'Real Steel' bike that I tend to use on jaunts with the missus, etc. To the extent that performance permits, I alternate between these three steeds. The actuarial tables suggest that my life is about ⅔rds over... but I expect that [absent collision-failure that would end the life of ANY bike], ALL THREE bikes will be usable- even after I die.
    Ecumenical Road Cyclist- multiple group-ride levels, multiple distances, multiple frame materials.
    Praying for the unity of all.
    Have Merckx-y on us.

  14. #64
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    Quote Originally Posted by Maelochs View Post
    Good lord, people how hard is it to figure this stuff out????


    If you don't want to buy Chinese CF, DON'T.

    It is not a difficult concept.

    The fewer people buy them, the lower the price, the more I can afford. Do everyone a favor and stick by that stand.
    And do us a favor and sign your organ donor card before the next time you get on your "budget" no-name Chinese carbon bike.
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
    -- Warren Buffett

    "Education is what you get when you read the fine print. Experience is what you get when you don't. -- Pete Seeger



  15. #65
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    Quote Originally Posted by Lombard View Post
    And do us a favor and sign your organ donor card before the next time you get on your "budget" no-name Chinese carbon bike.
    This and please self identify so we can give you the room you deserve :>)

  16. #66
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    Interesting website here of a German company that does destruction testing of bicycle frames.

    EFBE PrĂĽftechnik GmbH | Engineering for Bikes

    EFBe Prüftechnik - Full test results
    Last edited by Bremerradkurier; 1 Week Ago at 08:48 AM.

  17. #67
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    I've been riding my Giant Cadex 980c CF frame (with alloy lugs) for 27ish years now with no issues. Rides better than ever as a matter of fact.

  18. #68
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    Quote Originally Posted by Veloptuous View Post
    I've been riding my Giant Cadex 980c CF frame (with alloy lugs) for 27ish years now with no issues. Rides better than ever as a matter of fact.
    Sorry, dude, but I guess you didn't get the memo ... this has been declared a fact-free topic.

    You will be pardoned for your first offense ... so long as it is your last.

    ;)

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