Do carbon frames become more flexible over time?
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Do carbon frames become more flexible over time?
A newbie friend said he'd heard that carbon frames become more flexible over time, so he asked me about it. Before I laughed it off and told him it was silly, I thought I should do a quick Google, and found this:
"Carbon-fiber components actually do get softer with use. As the component flexes, the internal fibers break free of the surrounding resin and delaminate invisibly. When TOUR magazine tested carbon forks, they found that after 100,000 test cycles, some forks had lost a significant amount of their stiffness. Today, the European Union standards for fatigue resistance specify how much stiffness a carbon component may lose over the test cycle."
https://janheine.wordpress.com/2012/0...es-going-soft/
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"Carbon-fiber components actually do get softer with use. As the component flexes, the internal fibers break free of the surrounding resin and delaminate invisibly. When TOUR magazine tested carbon forks, they found that after 100,000 test cycles, some forks had lost a significant amount of their stiffness. Today, the European Union standards for fatigue resistance specify how much stiffness a carbon component may lose over the test cycle."
https://janheine.wordpress.com/2012/0...es-going-soft/
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#3
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A newbie friend said he'd heard that carbon frames become more flexible over time, so he asked me about it. Before I laughed it off and told him it was silly, I thought I should do a quick Google, and found this:
"Carbon-fiber components actually do get softer with use. As the component flexes, the internal fibers break free of the surrounding resin and delaminate invisibly. When TOUR magazine tested carbon forks, they found that after 100,000 test cycles, some forks had lost a significant amount of their stiffness. Today, the European Union standards for fatigue resistance specify how much stiffness a carbon component may lose over the test cycle."
https://janheine.wordpress.com/2012/0...es-going-soft/
**********
"Carbon-fiber components actually do get softer with use. As the component flexes, the internal fibers break free of the surrounding resin and delaminate invisibly. When TOUR magazine tested carbon forks, they found that after 100,000 test cycles, some forks had lost a significant amount of their stiffness. Today, the European Union standards for fatigue resistance specify how much stiffness a carbon component may lose over the test cycle."
https://janheine.wordpress.com/2012/0...es-going-soft/
**********
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#8
Jan Heine is a well known retro ******. Uh, I mean grouch. And you, of course,are a troll.
#9
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#10
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i would have thought CF becomes more brittle over time...hence the 'sploding.
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This take from an Alpha Q engineer in Leonard Zinn's column may be a bit more objective. https://velonews.competitor.com/2011/...g-tools_181993
According to him, CF forks can lose up to 5% stiffness after thousands of cycles of high fatigue loading involving forces exceeding what is routinely encountered riding around.
And given that the CF frame is going to be stiffer to start, it's still going to be fine for years and years of riding. Pretty much a non issue as a practical matter.
According to him, CF forks can lose up to 5% stiffness after thousands of cycles of high fatigue loading involving forces exceeding what is routinely encountered riding around.
And given that the CF frame is going to be stiffer to start, it's still going to be fine for years and years of riding. Pretty much a non issue as a practical matter.
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Just when I get curious if things have changed and it's safe to post over here again, I come across this stuff...
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That would be awesome. Imagine bragging to your friends that your legs are so strong you actually tore the fibers apart and delaminated the frame. It makes me almost want to abuse my CF bike just to see if I can break it. Definitely worth the bragging rights.
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Someone should blog about this.
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In my experience with an '07 TCR Composite, this is true. Confirmed by a co-worker whose team was sponsored by Giant and a knowledgeable lady I met at a coffee stop. Her TCR Composite turned to mush over time, too. Symptoms were visible sagging of frame when I sat on it, increasingly sloppy handling, increasing susceptibility to speed wobble, increasingly difficult to control in crosswinds, and loss of sprint. Nanofiber and higher compression rates used in the better contemporary frames is supposed to address this.
Think about it. Carbon fiber and epoxy are inert. They can't change chemically, but stress can break them (in theory). I'm going with theory. And my own observation.
Regarding steel, I've heard that a well brazed joint actually gets harder with use.
Think about it. Carbon fiber and epoxy are inert. They can't change chemically, but stress can break them (in theory). I'm going with theory. And my own observation.
Regarding steel, I've heard that a well brazed joint actually gets harder with use.
Last edited by oldbobcat; 10-29-12 at 09:28 PM.
#20
Yes, steel is so real, that the harder you use it the stronger it gets.
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This is fun.
Carbon frames are layers of fibers and resins. Over time small voids in the matrix can lead to "localized de-lamination" for lack of a better term. a broken fiber in a mesh of hundreds of thousands...yay. a hundred broken fibers at different points....thousands...over time if the construction techniques (molding and joint making) aren't well designed, thought out or executed they could lead to more microscopic voids or fiber breaks that would lead to a "softening" of the assembly.
In essence though - a non-issue for the vast majority of the frames and racers out there. The changes in layup techniques, frame shape, and resins account for large changes in the stiff "feel" of newer frames. Enough that it can be easy to get off of a frame from 3-5 years ago and get on a new one and mistakenly assume that the old one had "gone soft" because the difference in feel is just that drastic.
Carbon frames are layers of fibers and resins. Over time small voids in the matrix can lead to "localized de-lamination" for lack of a better term. a broken fiber in a mesh of hundreds of thousands...yay. a hundred broken fibers at different points....thousands...over time if the construction techniques (molding and joint making) aren't well designed, thought out or executed they could lead to more microscopic voids or fiber breaks that would lead to a "softening" of the assembly.
In essence though - a non-issue for the vast majority of the frames and racers out there. The changes in layup techniques, frame shape, and resins account for large changes in the stiff "feel" of newer frames. Enough that it can be easy to get off of a frame from 3-5 years ago and get on a new one and mistakenly assume that the old one had "gone soft" because the difference in feel is just that drastic.
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This take from an Alpha Q engineer in Leonard Zinn's column may be a bit more objective. https://velonews.competitor.com/2011/...g-tools_181993
According to him, CF forks can lose up to 5% stiffness after thousands of cycles of high fatigue loading involving forces exceeding what is routinely encountered riding around.
And given that the CF frame is going to be stiffer to start, it's still going to be fine for years and years of riding. Pretty much a non issue as a practical matter.
According to him, CF forks can lose up to 5% stiffness after thousands of cycles of high fatigue loading involving forces exceeding what is routinely encountered riding around.
And given that the CF frame is going to be stiffer to start, it's still going to be fine for years and years of riding. Pretty much a non issue as a practical matter.
#24
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I had just assumed that it was the riders getting fatter and weaker that was the issue, not that the bikes got weaker and flexier.
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#25
So I guess in a few years those big jets that are made of carbon fiber are going to start flapping their wings to take off?