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editorial opinion, steel frames



 
 
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  #51  
Old May 24th 17, 06:01 PM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default editorial opinion, steel frames

On Wednesday, May 24, 2017 at 8:00:17 AM UTC-7, Ralph Barone wrote:
jbeattie wrote:

snip
You're just guessing. Actual testing shows CF has better fatigue
resistance than aluminum or steel by a wide margin. Modern CF can be very
durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life
expectancy of CF is not a good thing. If you claim that CF testing is
"false," you should post a link to "true" testing.

-- Jay Beattie.


However, from the same link, note the different failure modes of Al and CF.
Aluminum bends and carbon fibre snaps, which is probably why Santa Cruz
designed their carbon frames with a higher safety factor. As with nearly
everything else out there, the correct answer is probably "It's
complicated..."


Well, its also complicated because the failure mode in a crash or massive front end over-load rarely matters because the rider is ejected. In the Santa Cruz tests, both the aluminum and CF bikes were trashed. No matter what material was used, the rider is walking home -- assuming he or she can walk after hitting the rock, wall, tree, etc. and getting thrown off the bike.

IMO, what matters is fatigue resistance and low energy impact resistance -- where the rider would not be ejected but for the failure, e.g., JRA fork or front-end failures. I have been riding on CF forks for 30 years without any problems, so I'm not overly concerned, but that doesn't mean one should not be concerned. That concern can be addressed in great part by buying CF forks from reputable manufacturers and not from some Chinese "company" (workers using molds and scraps after hours) that sells on eBay.

-- Jay Beattie.
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  #52  
Old May 24th 17, 08:52 PM posted to rec.bicycles.tech
[email protected]
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Posts: 3,345
Default editorial opinion, steel frames

On Wednesday, May 24, 2017 at 10:01:24 AM UTC-7, jbeattie wrote:
On Wednesday, May 24, 2017 at 8:00:17 AM UTC-7, Ralph Barone wrote:
jbeattie wrote:

snip
You're just guessing. Actual testing shows CF has better fatigue
resistance than aluminum or steel by a wide margin. Modern CF can be very
durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life
expectancy of CF is not a good thing. If you claim that CF testing is
"false," you should post a link to "true" testing.

-- Jay Beattie.


However, from the same link, note the different failure modes of Al and CF.
Aluminum bends and carbon fibre snaps, which is probably why Santa Cruz
designed their carbon frames with a higher safety factor. As with nearly
everything else out there, the correct answer is probably "It's
complicated..."


Well, its also complicated because the failure mode in a crash or massive front end over-load rarely matters because the rider is ejected. In the Santa Cruz tests, both the aluminum and CF bikes were trashed. No matter what material was used, the rider is walking home -- assuming he or she can walk after hitting the rock, wall, tree, etc. and getting thrown off the bike.

IMO, what matters is fatigue resistance and low energy impact resistance -- where the rider would not be ejected but for the failure, e.g., JRA fork or front-end failures. I have been riding on CF forks for 30 years without any problems, so I'm not overly concerned, but that doesn't mean one should not be concerned. That concern can be addressed in great part by buying CF forks from reputable manufacturers and not from some Chinese "company" (workers using molds and scraps after hours) that sells on eBay.


For the first two of my CF forks that may very well have been the problem especially since the IRS for had one side not glued to the fork-head at all. The way these things were built you smeared the resin on and pushed it over the fork-head and then it was held on with a rivet until it set.

But the Colnago could only be attributed to being too light for the applied forces.

But being too light is probably the name of the game with CF.
  #53  
Old May 24th 17, 09:36 PM posted to rec.bicycles.tech
Andre Jute[_2_]
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Posts: 10,422
Default editorial opinion, steel frames

On Tuesday, May 23, 2017 at 7:17:47 PM UTC+1, Duane wrote:
On 23/05/2017 1:29 PM, Andre Jute wrote:
On Tuesday, May 23, 2017 at 2:53:42 PM UTC+1, Duane wrote:


You're not the only one. On Sunday I rode out in long underwear and winter windbreaker. Today I rode in sandals and shirtsleeves. There's no accounting for the weather.

Andre Jute
Bring back global warming!


The key is that you rode both times. Same here.


Good point. In one of my professions my second-most-often quoted saying is, "A writer writes." (And the most widely quoted (1) and stolen (2) is just a more elegant variation of the same.) It applies to cycling too: a cyclist cycles.

Andre Jute
(1) http://coolmainpress.com/ajwriting/a...-can-stand-by/
(2) http://coolmainpress.com/ajwriting/w...tolen-from-me/
  #54  
Old May 25th 17, 07:43 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default editorial opinion, steel frames

On Wed, 24 May 2017 07:01:59 -0700 (PDT), wrote:

On Tuesday, May 23, 2017 at 10:15:21 PM UTC-7, John B. wrote:
On Tue, 23 May 2017 11:55:12 -0700 (PDT), jbeattie
wrote:

On Tuesday, May 23, 2017 at 11:00:39 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 7:05:49 AM UTC-7, jbeattie wrote:
On Tuesday, May 23, 2017 at 6:45:23 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 12:23:51 AM UTC-7, John B. wrote:
On Mon, 22 May 2017 08:14:38 -0700 (PDT),

wrote:

I've owned my Paramount since 1988, and it's dialed in to the Nth degree. I did it not by changing components or adjusting anything, but instead by having my body conform to the bike over the last 28 years.

I don't care what steel tubes you choose, though, I think CF has more compliance and is going to give you a more comfortable ride.

The problem is that a frame can be made extremely rigid or very
flexible not depending on the material but depending on the design. It
is quite possible to built an aluminum frame that is heavier then a
steel frame (I've got one) for example, and which certainly feels more
rigid then my road bike.

The whole argument about bike flexibility versus frame material is
just hokum. Yes, you can build an aluminum frame that is stiff, but
equally you can build a steel frame that is stiff, or even (shudder) a
C.F. frame that is stiff.

John, are you telling me that normal construction using normal materials is somehow going to make an aluminum frame both heavier and more rigid than a steel frame?

Likewise, because CF has a limited number of flexes before the resins give up do you think they are designing CF bikes to flex on purpose?

Even an old Trek OCLV frame has a better fatigue life than a classic steel frame.
https://www.sheldonbrown.com/rinard/...tigue_test.htm

And yes, they are designing CF bikes to flex on purpose.
http://roadbikeaction.com/home-page/...eed-decouplers

Oddly, CF can be stiff and flexible -- in different parts of the bike. My Roubaix has a very rigid BB but a soft-ish, slightly swampy tail, like a steel frame with longish chain stays. It is far easier to change carbon lay-up to tune the frame than to form steel tubes of different shapes and thickness.

-- Jay Beattie.

That sort of testing isn't very reliable. When new CF resins remain pliable for several years and then begin hardening and more liable for fracture. I haven't seen the OCLV Trek frames breaking but I assume they were really overbuilt and that also they were proclaimed "the lightest" is was all relative.

Furthermore, steel has a really sharp strength curve - it may have 80,000 cycles at the loading they were using and infinite at 3/4ths of that pressure. The same for AL. CF does not. As the resin hardens it fails period. It is only a matter of how close the loading is to the ultimate strength of the frame.

Al does not have a fatigue threshold, unlike steel. Enough low energy cycles

will fatigue aluminum. CF has a much higher fatigue limit than either
steel or aluminum. I haven't seen any testing of old CF/resin. If
you have a link, I'd like to see the science.

-- Jay Beattie.



There is a quite thorough study of fiberglass Coast Guard boats that
might be of interest.
http://www.ericgreeneassociates.com/..._Longevity.pdf

Which states that testing of a 40 ft. fiberglass hull was done after
10 years of use and again after 20 years of use. some of the findings
we
Tensile Strength 10 years - 5990 psi, 20 years - 6140 psi
Compression Strength 10 - 12,200 20 - 10,850
Flex Strength 10 - 9410 20 - 10850
Shear Strength 10 - 6560 20 6146

Note: the difference between 10 and 20 year averages was largely due
to the number of samples tested. The 10 year test used 1 - 3 samples
while the 20 year test was done with 10 samples for each test.

The argument that in some manner, the resins used fail after long
periods seems to be (well) a bit far fetched.


John, firstly these were fiberglas in very heavy layups. As you can see - half of the material is resin. By the time of the improvements to the submarines enough was known about resins that under Navy quality control the mixture of resin and hardener could be carefully controlled.


Apparently you didn't read the reference I posted. The boats weren't
submarines, they were 40 foot Coast Guard patrol boats and they
weren't built under Navy control. They were, apparently, built to some
Coast Guard approved design. They we
"Single skin FRP construction reinforced by
transverse aluminum frames, a decidedly conservative approach at the
time of construction. Laminate schedules consisted of alternating
plies of 10 ounce boat cloth and 1 ounce mat at 3/4 inch for the
bottom and 3/8 inch for the sides."

The first composite boat seems to have been built by Ray Greene of
Owens Corning in 1937, who, by the way, seem to have been the
suppliers for the materials, and did the testing,, of the Coast Guard
boats mentioned above. The argument that "those stupid boat builders
didn't know how to mix resin" in 1950, some 13 years after the first
CRP boat was built is (well) a bit silly.

As for lay up. The traditional method was to use the same weight of
resin as the weight of the cloth. i.e., for every square yard of 10 gm
cloth you wet it out with 10 gm. of resin. However that is the old,
traditional method and greatly improved methods are in use today. The
vacuum infusion and SCRIMP (tm) method uses far less resin and even
simple "vacuum bagging, where the wetted out cloth is placed in a
mold, covered with a plastic "bag" and a vacuum applied reduces resin
content significantly. Then, of course, we have the "Pre-Preg" method
where the dry pre impregnated cloth-resin material is placed in a mold
and cured in an autoclave.

The old hand lay up method results in fiber volume in the finished
composite of from 15 - 25% while the more modern methods can be as
much as 70" fiber. As much as a 50% reduction in resin and the
resulting increate in strength.


New bicycle frames need to be cranked off of an assembly line so they use materials that harden much more rapidly. And the layups are extremely thin. The Navy could wait a week for their components to harden.


Ah, but while hardening time is partly a factor of the resin mix
temperature has a far greater effect. The so called "rule of thumb"
states that for every 10 degrees increase in temperature the curing
time is halved. Many pre-preg materials used in aerospace
are impregnated with an epoxy resin and they are cured at
either 250 °F or 350 °F


Unfortunately most of the pictures of failed CF bikes are from accidents and that doesn't tell you a whole lot. But the bikes that fail independently could tell a story if they were carefully examined. From what I've seen on my stuff that failed, it appeared to be the resin failing and without the support the cloth tears.


I can only comment that in designing composites the predominate factor
seems to be fiber strength not resin strength.

The reference to testing of frames in which they failed in fatigue was entirely false testing. At 80-90% load steel is one of the most reliable materials with aluminum not far behind. It is the CF frames that probably degrade all the way down to 50% loading.

--
Cheers,

John B.

  #55  
Old May 25th 17, 08:03 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default editorial opinion, steel frames

On Wed, 24 May 2017 07:29:12 -0700 (PDT), jbeattie
wrote:

On Wednesday, May 24, 2017 at 7:02:01 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 10:15:21 PM UTC-7, John B. wrote:
On Tue, 23 May 2017 11:55:12 -0700 (PDT), jbeattie
wrote:

On Tuesday, May 23, 2017 at 11:00:39 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 7:05:49 AM UTC-7, jbeattie wrote:
On Tuesday, May 23, 2017 at 6:45:23 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 12:23:51 AM UTC-7, John B. wrote:
On Mon, 22 May 2017 08:14:38 -0700 (PDT),
wrote:

I've owned my Paramount since 1988, and it's dialed in to the Nth degree. I did it not by changing components or adjusting anything, but instead by having my body conform to the bike over the last 28 years.

I don't care what steel tubes you choose, though, I think CF has more compliance and is going to give you a more comfortable ride.

The problem is that a frame can be made extremely rigid or very
flexible not depending on the material but depending on the design. It
is quite possible to built an aluminum frame that is heavier then a
steel frame (I've got one) for example, and which certainly feels more
rigid then my road bike.

The whole argument about bike flexibility versus frame material is
just hokum. Yes, you can build an aluminum frame that is stiff, but
equally you can build a steel frame that is stiff, or even (shudder) a
C.F. frame that is stiff.

John, are you telling me that normal construction using normal materials is somehow going to make an aluminum frame both heavier and more rigid than a steel frame?

Likewise, because CF has a limited number of flexes before the resins give up do you think they are designing CF bikes to flex on purpose?

Even an old Trek OCLV frame has a better fatigue life than a classic steel frame.
https://www.sheldonbrown.com/rinard/...tigue_test.htm

And yes, they are designing CF bikes to flex on purpose.
http://roadbikeaction.com/home-page/...eed-decouplers

Oddly, CF can be stiff and flexible -- in different parts of the bike. My Roubaix has a very rigid BB but a soft-ish, slightly swampy tail, like a steel frame with longish chain stays. It is far easier to change carbon lay-up to tune the frame than to form steel tubes of different shapes and thickness.

-- Jay Beattie.

That sort of testing isn't very reliable. When new CF resins remain pliable for several years and then begin hardening and more liable for fracture. I haven't seen the OCLV Trek frames breaking but I assume they were really overbuilt and that also they were proclaimed "the lightest" is was all relative.

Furthermore, steel has a really sharp strength curve - it may have 80,000 cycles at the loading they were using and infinite at 3/4ths of that pressure. The same for AL. CF does not. As the resin hardens it fails period. It is only a matter of how close the loading is to the ultimate strength of the frame.

Al does not have a fatigue threshold, unlike steel. Enough low energy cycles
will fatigue aluminum. CF has a much higher fatigue limit than either
steel or aluminum. I haven't seen any testing of old CF/resin. If
you have a link, I'd like to see the science.

-- Jay Beattie.


There is a quite thorough study of fiberglass Coast Guard boats that
might be of interest.
http://www.ericgreeneassociates.com/..._Longevity.pdf

Which states that testing of a 40 ft. fiberglass hull was done after
10 years of use and again after 20 years of use. some of the findings
we
Tensile Strength 10 years - 5990 psi, 20 years - 6140 psi
Compression Strength 10 - 12,200 20 - 10,850
Flex Strength 10 - 9410 20 - 10850
Shear Strength 10 - 6560 20 6146

Note: the difference between 10 and 20 year averages was largely due
to the number of samples tested. The 10 year test used 1 - 3 samples
while the 20 year test was done with 10 samples for each test.

The argument that in some manner, the resins used fail after long
periods seems to be (well) a bit far fetched.


John, firstly these were fiberglas in very heavy layups. As you can see - half of the material is resin. By the time of the improvements to the submarines enough was known about resins that under Navy quality control the mixture of resin and hardener could be carefully controlled.

New bicycle frames need to be cranked off of an assembly line so they use materials that harden much more rapidly. And the layups are extremely thin. The Navy could wait a week for their components to harden.

Unfortunately most of the pictures of failed CF bikes are from accidents and that doesn't tell you a whole lot. But the bikes that fail independently could tell a story if they were carefully examined. From what I've seen on my stuff that failed, it appeared to be the resin failing and without the support the cloth tears.

The reference to testing of frames in which they failed in fatigue was entirely false testing. At 80-90% load steel is one of the most reliable materials with aluminum not far behind. It is the CF frames that probably degrade all the way down to 50% loading.


You're just guessing. Actual testing shows CF has better fatigue resistance than aluminum or steel by a wide margin. Modern CF can be very durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life expectancy of CF is not a good thing. If you claim that CF testing is "false," you should post a link to "true" testing.

-- Jay Beattie.


Steel golf club shafts date back to about 1920 and were first allowed
in the U.S. open in 1924. In 1931 when Billy Burke won the US Open, he
was the first golfer to win using steel shaft clubs.

Aluminum shafts were popular for a while in the 1960's to mid 1970's.

"Graphite" golf club shafts seem to date back to 1969 when Shakespeare
(I believe) started making them and by the early 1970's, graphite
shafts were widely available to the golfing world and by 1973, they
were taking the industry by storm.

I doubt that there is a Professional playing on any tour today that is
not using "graphite" shafts.
--
Cheers,

John B.

  #56  
Old May 25th 17, 08:28 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default editorial opinion, steel frames

On Wed, 24 May 2017 08:06:04 -0700 (PDT), wrote:

On Wednesday, May 24, 2017 at 7:29:15 AM UTC-7, jbeattie wrote:
On Wednesday, May 24, 2017 at 7:02:01 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 10:15:21 PM UTC-7, John B. wrote:
On Tue, 23 May 2017 11:55:12 -0700 (PDT), jbeattie
wrote:

On Tuesday, May 23, 2017 at 11:00:39 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 7:05:49 AM UTC-7, jbeattie wrote:
On Tuesday, May 23, 2017 at 6:45:23 AM UTC-7, wrote:
On Tuesday, May 23, 2017 at 12:23:51 AM UTC-7, John B. wrote:
On Mon, 22 May 2017 08:14:38 -0700 (PDT),

wrote:

I've owned my Paramount since 1988, and it's dialed in to the Nth degree. I did it not by changing components or adjusting anything, but instead by having my body conform to the bike over the last 28 years.

I don't care what steel tubes you choose, though, I think CF has more compliance and is going to give you a more comfortable ride.

The problem is that a frame can be made extremely rigid or very
flexible not depending on the material but depending on the design. It
is quite possible to built an aluminum frame that is heavier then a
steel frame (I've got one) for example, and which certainly feels more
rigid then my road bike.

The whole argument about bike flexibility versus frame material is
just hokum. Yes, you can build an aluminum frame that is stiff, but
equally you can build a steel frame that is stiff, or even (shudder) a
C.F. frame that is stiff.

John, are you telling me that normal construction using normal materials is somehow going to make an aluminum frame both heavier and more rigid than a steel frame?

Likewise, because CF has a limited number of flexes before the resins give up do you think they are designing CF bikes to flex on purpose?

Even an old Trek OCLV frame has a better fatigue life than a classic steel frame.
https://www.sheldonbrown.com/rinard/...tigue_test.htm

And yes, they are designing CF bikes to flex on purpose.
http://roadbikeaction.com/home-page/...eed-decouplers

Oddly, CF can be stiff and flexible -- in different parts of the bike. My Roubaix has a very rigid BB but a soft-ish, slightly swampy tail, like a steel frame with longish chain stays. It is far easier to change carbon lay-up to tune the frame than to form steel tubes of different shapes and thickness.

-- Jay Beattie.

That sort of testing isn't very reliable. When new CF resins remain pliable for several years and then begin hardening and more liable for fracture. I haven't seen the OCLV Trek frames breaking but I assume they were really overbuilt and that also they were proclaimed "the lightest" is was all relative.

Furthermore, steel has a really sharp strength curve - it may have 80,000 cycles at the loading they were using and infinite at 3/4ths of that pressure. The same for AL. CF does not. As the resin hardens it fails period. It is only a matter of how close the loading is to the ultimate strength of the frame.

Al does not have a fatigue threshold, unlike steel. Enough low energy cycles
will fatigue aluminum. CF has a much higher fatigue limit than either
steel or aluminum. I haven't seen any testing of old CF/resin. If
you have a link, I'd like to see the science.

-- Jay Beattie.


There is a quite thorough study of fiberglass Coast Guard boats that
might be of interest.
http://www.ericgreeneassociates.com/..._Longevity.pdf

Which states that testing of a 40 ft. fiberglass hull was done after
10 years of use and again after 20 years of use. some of the findings
we
Tensile Strength 10 years - 5990 psi, 20 years - 6140 psi
Compression Strength 10 - 12,200 20 - 10,850
Flex Strength 10 - 9410 20 - 10850
Shear Strength 10 - 6560 20 6146

Note: the difference between 10 and 20 year averages was largely due
to the number of samples tested. The 10 year test used 1 - 3 samples
while the 20 year test was done with 10 samples for each test.

The argument that in some manner, the resins used fail after long
periods seems to be (well) a bit far fetched.

John, firstly these were fiberglas in very heavy layups. As you can see - half of the material is resin. By the time of the improvements to the submarines enough was known about resins that under Navy quality control the mixture of resin and hardener could be carefully controlled.

New bicycle frames need to be cranked off of an assembly line so they use materials that harden much more rapidly. And the layups are extremely thin. The Navy could wait a week for their components to harden.

Unfortunately most of the pictures of failed CF bikes are from accidents and that doesn't tell you a whole lot. But the bikes that fail independently could tell a story if they were carefully examined. From what I've seen on my stuff that failed, it appeared to be the resin failing and without the support the cloth tears.

The reference to testing of frames in which they failed in fatigue was entirely false testing. At 80-90% load steel is one of the most reliable materials with aluminum not far behind. It is the CF frames that probably degrade all the way down to 50% loading.


You're just guessing. Actual testing shows CF has better fatigue resistance than aluminum or steel by a wide margin. Modern CF can be very durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life expectancy of CF is not a good thing. If you claim that CF testing is "false," you should post a link to "true" testing.


I'm not guessing and all you have to do is actually read the article and watch the testing to see that it only has to do with maximum stress testing NEW frames. This is not a good test of CF since we know that they usually start breaking after a couple of years of use. There are large groups that have been using the same steel bikes for 40 years or even more without a failure in the group because as I said, maximum strength is not a practical measure except in initial design.



Interesting. Of course there is some dissension.

"Carbon composites and manufacturing methods have evolved considerably
since the mid-'80'ss and independent testing has consistently
demonstrated superior fatigue resistance for the material. "The
fatigue tests that we run here are almost a matter of going through
the motions", said Chuck Texiera, a senior engineer at Specialized.
"We just about never see a failure or fatigue. Once you hit expected
ultimate strength, the fatigue is like a gimme. If you subjected any
type of metal frame, including titanium, to the same total cycles,
typically they would not withstand it."

When I put the question of the life span of a carbon bike to Benoit
Grelier, the person in charge of Scott's bicycle engineering, his
answer was clear, "I think it can last your life, actually."

Scott Nielson has worked with carbon fibre for over a decade, starting
with Trek, and is now the vice president of research and development
and engineering at Enve. 'If you look at carbon materials in general",
he said, "they're very good in fatigue, much better than any aluminum
or steel would be. If done properly, a frame could last you forever."
--
Cheers,

John B.

  #57  
Old May 25th 17, 03:07 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,345
Default editorial opinion, steel frames

On Thursday, May 25, 2017 at 12:28:55 AM UTC-7, John B. wrote:

Interesting. Of course there is some dissension.

"Carbon composites and manufacturing methods have evolved considerably
since the mid-'80'ss and independent testing has consistently
demonstrated superior fatigue resistance for the material. "The
fatigue tests that we run here are almost a matter of going through
the motions", said Chuck Texiera, a senior engineer at Specialized.
"We just about never see a failure or fatigue. Once you hit expected
ultimate strength, the fatigue is like a gimme. If you subjected any
type of metal frame, including titanium, to the same total cycles,
typically they would not withstand it."

When I put the question of the life span of a carbon bike to Benoit
Grelier, the person in charge of Scott's bicycle engineering, his
answer was clear, "I think it can last your life, actually."

Scott Nielson has worked with carbon fibre for over a decade, starting
with Trek, and is now the vice president of research and development
and engineering at Enve. 'If you look at carbon materials in general",
he said, "they're very good in fatigue, much better than any aluminum
or steel would be. If done properly, a frame could last you forever."


CF is being used because they can make frames and forks lighter. As I said, I have myself seen so many cracks in CF frames that I simply don't trust the material.

I wrote to the UCI because they were talking about dropping the weight limit altogether and suggested that if they take off the 16 lb limit (they presently have) that they will see 10 lb bikes and that the man-on-the-street will be buying them. And that injuries from those sorts of bikes breaking will rapidly give bicycling such a bad name that their audience will turn away just as the doping scandals took away about 20% of their audience.

The letter I got in return said something to the effect that a 10 lb bike might be stronger than a 16 lb bike. So I would expect to shortly see the weight limit completely removed.

What was clear from the data on both the CG patrol boat and the submarine fairwater is that the resins continued to harden with age. The sheer strength dropped 6% between 10 years and 20 years.

The cycling curve showed a FAR more disturbing set of numbers though - more than a 50% loss of strength with increasing flex.

I would guess without any further data that it is just as I've been saying - the failures of these frames are from the resins turning to powder from the continuous vibrations which acts on these light frames as the bending stresses do on those old tests.
  #58  
Old May 25th 17, 05:53 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default editorial opinion, steel frames

On 5/24/2017 1:01 PM, jbeattie wrote:
On Wednesday, May 24, 2017 at 8:00:17 AM UTC-7, Ralph Barone wrote:
jbeattie wrote:

snip
You're just guessing. Actual testing shows CF has better fatigue
resistance than aluminum or steel by a wide margin. Modern CF can be very
durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life
expectancy of CF is not a good thing. If you claim that CF testing is
"false," you should post a link to "true" testing.

-- Jay Beattie.


However, from the same link, note the different failure modes of Al and CF.
Aluminum bends and carbon fibre snaps, which is probably why Santa Cruz
designed their carbon frames with a higher safety factor. As with nearly
everything else out there, the correct answer is probably "It's
complicated..."


Well, its also complicated because the failure mode in a crash or massive front end over-load rarely matters because the rider is ejected. In the Santa Cruz tests, both the aluminum and CF bikes were trashed. No matter what material was used, the rider is walking home -- assuming he or she can walk after hitting the rock, wall, tree, etc. and getting thrown off the bike.

IMO, what matters is fatigue resistance and low energy impact resistance -- where the rider would not be ejected but for the failure, e.g., JRA fork or front-end failures. I have been riding on CF forks for 30 years without any problems, so I'm not overly concerned, but that doesn't mean one should not be concerned. That concern can be addressed in great part by buying CF forks from reputable manufacturers and not from some Chinese "company" (workers using molds and scraps after hours) that sells on eBay.


I think there's little doubt that CF frames and forks, well done, can
certainly be both stronger and lighter than metal frames.

But ISTM that CF reliability is more dependent on being done well. CF
done cheaply or badly seems more likely to have undetectable problems
and catastrophic failures. Steel can have undetectable problems, as my
tandem fork proved (after 30+ years), but I think the techniques for
proper steel construction are much more widely known, and perhaps more
likely to be properly used.

Here's why I think all this matters to Jan Heine's market: His favorite
bike designs tend to be different from most of the current fashions. So
a lot of the bikes he'd love would be small production projects, or even
one-off customs.

Custom steel builders can add innovative features while still using
conservative and well-proven design and manufacturing techniques.
Custom CF seems more likely to be done by guess and by golly, with
consecutive frames much less likely to be similar in strength. And
there probably won't be much testing done to verify designs. You may
not know how well the bike you buy was actually constructed.

BTW, about the differences in ride harshness: I've got many friends who
used to ride metal and now ride CF. Not one of them have told me the CF
makes much difference in ride quality. But YMMV.

--
- Frank Krygowski
  #59  
Old May 25th 17, 06:59 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,345
Default editorial opinion, steel frames

On Thursday, May 25, 2017 at 9:53:24 AM UTC-7, Frank Krygowski wrote:
On 5/24/2017 1:01 PM, jbeattie wrote:
On Wednesday, May 24, 2017 at 8:00:17 AM UTC-7, Ralph Barone wrote:
jbeattie wrote:

snip
You're just guessing. Actual testing shows CF has better fatigue
resistance than aluminum or steel by a wide margin. Modern CF can be very
durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life
expectancy of CF is not a good thing. If you claim that CF testing is
"false," you should post a link to "true" testing.

-- Jay Beattie.

However, from the same link, note the different failure modes of Al and CF.
Aluminum bends and carbon fibre snaps, which is probably why Santa Cruz
designed their carbon frames with a higher safety factor. As with nearly
everything else out there, the correct answer is probably "It's
complicated..."


Well, its also complicated because the failure mode in a crash or massive front end over-load rarely matters because the rider is ejected. In the Santa Cruz tests, both the aluminum and CF bikes were trashed. No matter what material was used, the rider is walking home -- assuming he or she can walk after hitting the rock, wall, tree, etc. and getting thrown off the bike.

IMO, what matters is fatigue resistance and low energy impact resistance -- where the rider would not be ejected but for the failure, e.g., JRA fork or front-end failures. I have been riding on CF forks for 30 years without any problems, so I'm not overly concerned, but that doesn't mean one should not be concerned. That concern can be addressed in great part by buying CF forks from reputable manufacturers and not from some Chinese "company" (workers using molds and scraps after hours) that sells on eBay.


I think there's little doubt that CF frames and forks, well done, can
certainly be both stronger and lighter than metal frames.

But ISTM that CF reliability is more dependent on being done well. CF
done cheaply or badly seems more likely to have undetectable problems
and catastrophic failures. Steel can have undetectable problems, as my
tandem fork proved (after 30+ years), but I think the techniques for
proper steel construction are much more widely known, and perhaps more
likely to be properly used.

Here's why I think all this matters to Jan Heine's market: His favorite
bike designs tend to be different from most of the current fashions. So
a lot of the bikes he'd love would be small production projects, or even
one-off customs.

Custom steel builders can add innovative features while still using
conservative and well-proven design and manufacturing techniques.
Custom CF seems more likely to be done by guess and by golly, with
consecutive frames much less likely to be similar in strength. And
there probably won't be much testing done to verify designs. You may
not know how well the bike you buy was actually constructed.

BTW, about the differences in ride harshness: I've got many friends who
used to ride metal and now ride CF. Not one of them have told me the CF
makes much difference in ride quality. But YMMV.

--
- Frank Krygowski


Well, here's one person who has had all materials and I can tell you for sure that most CF bikes ride extremely rigid. But not all. My Time Edge is so stiff that you had a hard time riding it at all while my Look 247 uses aluminum lugs and straight tubes that have a LOT if flex in them. The C40 was very stiff and you would stand over just about any bump. The all aluminum Dream Reflux was the same way. The more advanced Dream HP with carbon rear triangle was better but it was probably because of the B stay and not the CF itself. The Colnago "Carbon" fork which was their strongest could hit so hard that you were afraid to ride it on bumpy roads. The steel bikes I had that were great were the Eddy Merckx Strata OS, the Eddy Merckx Corsa Extra and my various Bassos.

When I first went back to steel the difference was stunning. But now that I'm used to it I can feel bumps with the steel that I thought of as smooth road before. But I'm also not riding the hard bikes.
  #60  
Old May 26th 17, 01:50 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default editorial opinion, steel frames

On Thu, 25 May 2017 07:07:18 -0700 (PDT), wrote:

On Thursday, May 25, 2017 at 12:28:55 AM UTC-7, John B. wrote:

Interesting. Of course there is some dissension.

"Carbon composites and manufacturing methods have evolved considerably
since the mid-'80'ss and independent testing has consistently
demonstrated superior fatigue resistance for the material. "The
fatigue tests that we run here are almost a matter of going through
the motions", said Chuck Texiera, a senior engineer at Specialized.
"We just about never see a failure or fatigue. Once you hit expected
ultimate strength, the fatigue is like a gimme. If you subjected any
type of metal frame, including titanium, to the same total cycles,
typically they would not withstand it."

When I put the question of the life span of a carbon bike to Benoit
Grelier, the person in charge of Scott's bicycle engineering, his
answer was clear, "I think it can last your life, actually."

Scott Nielson has worked with carbon fibre for over a decade, starting
with Trek, and is now the vice president of research and development
and engineering at Enve. 'If you look at carbon materials in general",
he said, "they're very good in fatigue, much better than any aluminum
or steel would be. If done properly, a frame could last you forever."


CF is being used because they can make frames and forks lighter. As I said, I have myself seen so many cracks in CF frames that I simply don't trust the material.

I wrote to the UCI because they were talking about dropping the weight limit altogether and suggested that if they take off the 16 lb limit (they presently have) that they will see 10 lb bikes and that the man-on-the-street will be buying them. And that injuries from those sorts of bikes breaking will rapidly give bicycling such a bad name that their audience will turn away just as the doping scandals took away about 20% of their audience.

The letter I got in return said something to the effect that a 10 lb bike might be stronger than a 16 lb bike. So I would expect to shortly see the weight limit completely removed.

What was clear from the data on both the CG patrol boat and the submarine fairwater is that the resins continued to harden with age. The sheer strength dropped 6% between 10 years and 20 years.

The cycling curve showed a FAR more disturbing set of numbers though - more than a 50% loss of strength with increasing flex.

I would guess without any further data that it is just as I've been saying - the failures of these frames are from the resins turning to powder from the continuous vibrations which acts on these light frames as the bending stresses do on those old tests.


You seem to have some sort of fetish about resins. Here is an excerpt
from the conclusions taken from a study, dated 2011, of epoxy resins
as used in bicycle frames:

Physical Aging of Epoxy Polymers and Their Composites
G.M. Odegard and A. Bandyopadhyay
Department of Mechanical Engineering - Engineering Mechanics
Michigan Technological University
1400 Townsend Drive
Houghton, MI 49931, USA

The primary structural application of epoxies is in fiber-reinforced
composites. The long fiber geometry provides for an exceptional amount
of load transfer from the relatively brittle epoxy
matrix to the stiff and strong reinforcement. Because it is imperative
that this load transfer be maintained during the service life of a
composite component, there is considerable interest in
physical aging of these materials. Several studies have been conducted
on the physical aging of fiberous epoxy composites. In general, these
studies indicate that the composite material response to physical
aging is very similar to the corresponding response of neat epoxy
resin. The presence of glass or carbon fibers has little influence on
the physical aging characteristics. It is also clear that physical
aging has little influence on the strength of the fiber/epoxy
interface, which indicates that physical aging does not alter the
load-transfer characteristics of fiber-reinforced composites.
--
Cheers,

John B.

 




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