Is carbon really stronger than steel?
10-22-05, 02:19 AM
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Is carbon really stronger than steel?
I don't think so. I don't trust anything with resin and epoxy in it.
I have visions of carbon frames melting in the desert sun!
I have visions of carbon frames melting in the desert sun!
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10-22-05, 02:48 AM
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Wouldn't talking with [Moderator Removed: Sarcastic, off topic] on your head do just as well?
10-22-05, 03:40 AM
#3
Aluminium Crusader :-)
how much will a frame made from carbon nanotubes cost?
https://www.eastonbike.com/TECH_FAQ/tech_cnt.html
https://www.eastonbike.com/TECH_FAQ/tech_cnt.html
10-22-05, 03:41 AM
#4
Aluminium Crusader :-)
how much will a frame made from carbon nanotubes cost? 
https://www.eastonbike.com/TECH_FAQ/tech_cnt.html
https://www.eastonbike.com/TECH_FAQ/tech_cnt.html
10-22-05, 03:51 AM
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Carbon, unlike steel or aluminum, does not have a "memory"...where it flexes, it will retain its original shape. If you flex and bend steel enough, it gets soft. That's one great reason for a carbon fork. Al forks, for example, get flexy over time. Carbon will not.
10-22-05, 03:59 AM
#6
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It comes down to the numbers...
"Is carbon really stronger than steel?"
Lighter for same size, YES.
Stronger for same size, NO.
Stiffer for the same weight, YES.
Stronger for the same weight, YES.
"I don't think so. I don't trust anything with resin and epoxy in it."
That's what they said about aluminium too.
"I have visions of carbon frames melting in the desert sun!"
Uh... again, numbers. At what temperatures? How much softening do you get at what temperatures? Epoxies cure to yield a product that DO NOT melt. It will burn before it melts. I've used carbon-fibre for engine-parts that face up to 300 degrees-F without any problems at all.
"Is carbon really stronger than steel?"
Lighter for same size, YES.
Stronger for same size, NO.
Stiffer for the same weight, YES.
Stronger for the same weight, YES.
"I don't think so. I don't trust anything with resin and epoxy in it."
That's what they said about aluminium too.
"I have visions of carbon frames melting in the desert sun!"
Uh... again, numbers. At what temperatures? How much softening do you get at what temperatures? Epoxies cure to yield a product that DO NOT melt. It will burn before it melts. I've used carbon-fibre for engine-parts that face up to 300 degrees-F without any problems at all.
10-22-05, 05:06 AM
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I love that strength/weight graph with the entry for "steel". Check the Reynolds website and you will see a more realistic comparison of relative characteristics of materials.
Steel comes in variety of forms from low grade "hi ten", bog standard "chromoly" to upmarket, heat-treated supersteels like Reynolds 853 with tensile strenth varying across the range.
Steel comes in variety of forms from low grade "hi ten", bog standard "chromoly" to upmarket, heat-treated supersteels like Reynolds 853 with tensile strenth varying across the range.
10-22-05, 05:19 AM
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Can you define for us what exactly you mean by "stronger"?
10-22-05, 08:03 AM
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Originally Posted by Retro Grouch
Can you define for us what exactly you mean by "stronger"?
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10-22-05, 08:04 AM
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Originally Posted by gmason
Wouldn't talking with [Moderator Removed] on your head do just as well?
.
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Last edited by Sincitycycler; 10-22-05 at 01:45 PM.
10-22-05, 08:29 AM
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Originally Posted by Sincitycycler
I don't think so. I don't trust anything with resin and epoxy in it.
I have visions of carbon frames melting in the desert sun!
I have visions of carbon frames melting in the desert sun!
uh huh.... I'm sure the Vegas airport is littered with melted planes. If it's in common use in aerospace, it will work on a bike. It's not the material, but the fabrication.
And calling people frogs isn't likely to find you a local riding partner/contact for a future cycling trip to the alps.
10-22-05, 08:35 AM
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Carbon fiber is stronger than steel but only OZ for OZ. A carbon rod that weights in at 1 pound is stronger than a 1 pound rod of steel. I cant remember the claimed strength of carbon fiber but its like 10x as strong. So a 1 inch thick rod of carbon fiber is as strong as a 10 inch thick steel bar. Something of that nature.
10-22-05, 08:42 AM
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Originally Posted by Sincitycycler
I don't think so. I don't trust anything with resin and epoxy in it.
I have visions of carbon frames melting in the desert sun!
I have visions of carbon frames melting in the desert sun!
Putting the bike in at night will iliminate that concern though.
10-22-05, 10:21 AM
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All materials have positives and negatives. Your synthesis of the information about frame material choices just sounds like a predjudice against organic in favor of inorganic.
I have had several steel-famed road bikes. My last one was my favorite; and, it had a carbon fork. Imagine how much abuse a fork takes.
I have had several steel-famed road bikes. My last one was my favorite; and, it had a carbon fork. Imagine how much abuse a fork takes.
Last edited by wagathon; 10-22-05 at 06:04 PM.
10-22-05, 11:12 AM
#16
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Originally Posted by Sincitycycler
A better frame for a bike than steel for bigger riders (200lbs)? How does carbon hold up over 10 years +.
10-22-05, 12:10 PM
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I have to say, that's about the dumbest graph I've ever seen...it tells you absolutely nothing that a materials engineer would need to know. ....just a classic example of a graph by the marketing department for the market.
10-22-05, 12:11 PM
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Originally Posted by roadwarrior
Carbon, unlike steel or aluminum, does not have a "memory"...where it flexes, it will retain its original shape. If you flex and bend steel enough, it gets soft. That's one great reason for a carbon fork. Al forks, for example, get flexy over time. Carbon will not.
10-22-05, 12:34 PM
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It would depend more on the materials application and execution.
In the stress test following, the only frames not to break after a lot of stress cycles was the C'Dale & Principa Aluminum and Trek Carbon frames.
Full Test here
In the stress test following, the only frames not to break after a lot of stress cycles was the C'Dale & Principa Aluminum and Trek Carbon frames.
Full Test here
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Last edited by ViperZ; 10-22-05 at 12:42 PM.
10-22-05, 12:48 PM
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Carbon stonger than steel...the question is how are the properties of the material applied to the problem.
A rod of carbon is stronger than a rod of steel....
How thick is the rod? What kind of steel? Is it stronger in compression or tension? What about shear? Section modulus? Elasticity? ..and then there's all that messy frame geometry, etc...deflection, camber, shear, bending moments, etc...
It's not the material, but how it's used to accomplish the job that needs to be done.
Carbon is also made to bend in most applications..if an aircraft wing were rigid, there'd be some pretty big problems....The thing your looking for in the whole "memory" thing is the elasticity for a particular material. Where is the yield point? ductility? ulitimate strength? and ultimate fracture point... relative to steel, both CF as applied to bicycles and AL are more brittle, i.e., it will break with very little evidence of deformation, but most won't approach those. Brittleness is generally not a good thing in any structural engineering application.
If you look up a stress/strain diagram, you can begin to see all the properties that a materials engineer has to take in account. Strong but brittle, ductile and tough... etc..
Then there are strain rates, temperature effects (extreme cold and hot...again, think airplanes and how cold it is at 35,000 ft and how hot it is in July at the gate in Las Vegas), creep, endurance ratio, fatique, etc...
Saying "which is stronger?" is a very relative problem. Then there's hardness, abrasion resistance, etc... the list gets long and ugly, but at some point in the production of a bike, someone has considered all of these.
Viper, thanks for the fatique chart you posted above. Interesting where the SLX's failed...at the place most likely to vary, the hand brazed connection!
A rod of carbon is stronger than a rod of steel....
How thick is the rod? What kind of steel? Is it stronger in compression or tension? What about shear? Section modulus? Elasticity? ..and then there's all that messy frame geometry, etc...deflection, camber, shear, bending moments, etc...
It's not the material, but how it's used to accomplish the job that needs to be done.
Carbon is also made to bend in most applications..if an aircraft wing were rigid, there'd be some pretty big problems....The thing your looking for in the whole "memory" thing is the elasticity for a particular material. Where is the yield point? ductility? ulitimate strength? and ultimate fracture point... relative to steel, both CF as applied to bicycles and AL are more brittle, i.e., it will break with very little evidence of deformation, but most won't approach those. Brittleness is generally not a good thing in any structural engineering application.
If you look up a stress/strain diagram, you can begin to see all the properties that a materials engineer has to take in account. Strong but brittle, ductile and tough... etc..
Then there are strain rates, temperature effects (extreme cold and hot...again, think airplanes and how cold it is at 35,000 ft and how hot it is in July at the gate in Las Vegas), creep, endurance ratio, fatique, etc...
Saying "which is stronger?" is a very relative problem. Then there's hardness, abrasion resistance, etc... the list gets long and ugly, but at some point in the production of a bike, someone has considered all of these.
Viper, thanks for the fatique chart you posted above. Interesting where the SLX's failed...at the place most likely to vary, the hand brazed connection!
Last edited by puddin' legs; 10-22-05 at 01:12 PM.
10-22-05, 12:51 PM
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Originally Posted by TheDTrain
Sincitycyclist just got served, by science!
10-22-05, 01:35 PM
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Originally Posted by nova
Dont worry bout it. The resin in carbon frames are heat set. I beleive 270 or 350 f. What youd need to worry about is if the climate you live in has realy hot days and realy cold nights. The temp diffrence will cause the resin to become brittle over time. If a typical carbon frame lasts say 25 years in a moderate climate where the night and day are say 80 to 100 day time and 50 to 70 night time. You can asume a climate where it goes from 80 to 100 to 30 to 50 at night you can shave off a few years in life span say 5 years.
Putting the bike in at night will iliminate that concern though.
Putting the bike in at night will iliminate that concern though.
really hot days
! That's what I was afraid of spending $2000-4000 on something that won't last a lifetime. I'll stick with steel. DeRosa Neo Primato next year....hmmm...lugged frame...aahh... 
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10-22-05, 01:53 PM
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Tensile Yield Elongation Fatigue...all can fall under the strength category and all materials have different numbers.
10-22-05, 02:00 PM
#24
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Originally Posted by Sincitycycler
[SIZE=3]100-110 degrees summertime ! That's what I was afraid of spending $2000-4000 on something that won't last a lifetime. I'll stick with steel. DeRosa Neo Primato next year....hmmm...lugged frame...aahh...
! That's what I was afraid of spending $2000-4000 on something that won't last a lifetime. I'll stick with steel. DeRosa Neo Primato next year....hmmm...lugged frame...aahh...
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10-22-05, 02:22 PM
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Originally Posted by garysol1
Beautiful bike that DeRosa. I am thinking you started this thread but really never cared about the answer. You just wanted to feel better about your decision to buy steel. If you prefer steel than that is what you need to get. Not because it is better than Carbon but because YOU want it.
I just want to know if I'm missing anything by not owning a carbon bike since that seems to be the rage these days
.Nothing more gorgeous lookng than a steel lugged classic IMO
.
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