https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
>
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971
Andrew, is the use of carbon fiber tubes with titanium lugs proven technology? Are the tubes glued to the lugs?

On Fri, 22 Apr 2022 09:41:24 -0500, AMuzi <am@yellowjersey.org> wrote:

>https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/

"A complete carbon Colnago C68 build with Shimano Dura-Ace Di2, disc
brakes and Dura-Ace C50 carbon wheels sells for $16,000 / 14,065
euros."

Ouch. Even if Tom sells his five bicycles on eBay for his total
asking price of $9,400, he still couldn't afford a C68:
<https://www.ebay.com/sch/tomk37/m.html>

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/

Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.

On 4/22/2022 10:15 AM, William Crowell wrote:
> On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
>>
>> --
>> Andrew Muzi
>> <www.yellowjersey.org/>
>> Open every day since 1 April, 1971
> Andrew, is the use of carbon fiber tubes with titanium lugs proven technology? Are the tubes glued to the lugs?
>

Since the 1980s and in most modern airplanes. Not a new
technology although adhesive development has been amazingly
sophisticated.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Friday, April 22, 2022 at 10:18:50 AM UTC-7, AMuzi wrote:
> On 4/22/2022 10:15 AM, William Crowell wrote:
> > On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
> >> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
> >>
> >> --
> >> Andrew Muzi
> >> <www.yellowjersey.org/>
> >> Open every day since 1 April, 1971
> > Andrew, is the use of carbon fiber tubes with titanium lugs proven technology? Are the tubes glued to the lugs?
> >
> Since the 1980s and in most modern airplanes. Not a new
> technology although adhesive development has been amazingly
> sophisticated.

Modern high performance military aircraft in particular have been using composite materials for a long time to reduce radar signature. I believe that most of the panels on a B52H have been replaced with composites but they have to have a strict replacement policy since composites fail after a given number of stress cycles. For that matter so do metals, but the numbers of stress cycles is not even in the same ball park.

In bicycles the failures are often catastrophic because the intent is to make them as light as possible. Weight is further down the list in Aerospace. Plus, metal construction tends to be far stronger in the important areas such as the bottom bracket or the steering head and these are the places less likely to fail without lots and lots of warning.

They are now replacing the old and decrepit B52 engines with commercial grade engines used on commercial jetliners. This leads to the idea that there may be a supersonic B52 in the not too distant future. We HAVE these planes now and it would require nothing more than reinforcing whereas a B2 costs now in the billions per.

On 4/22/2022 1:35 PM, Tom Kunich wrote:
>
> They are now replacing the old and decrepit B52 engines with commercial grade engines used on commercial jetliners. This leads to the idea that there may be a supersonic B52 in the not too distant future. We HAVE these planes now and it would require nothing more than reinforcing whereas a B2 costs now in the billions per.

<sigh> No, Tom, we're not going to have supersonic B-52s. There's a lot
more to supersonic flight than just pushing harder. The aerodynamics are
very, very different.

Admittedly, the class I took covering supersonic aerodynamics was long,
long ago. When did you take a course on that subject?

--
- Frank Krygowski

On Fri, 22 Apr 2022 09:52:31 -0700 (PDT), Tom Kunich
<cyclintom@gmail.com> wrote:

>On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
>
>Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.

Perfect score. Everything you've posted today has been wrong.

"Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
Polymers"
<https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
"Therefore, there is no significant gap between titanium and
carbon-fiber-reinforced composite to create galvanic corrosion. This
means that commercially pure titanium and its alloys are completely
resistant to galvanic corrosion when they are coupled with carbon
composites"

Extra credit. What is an "electrostatically insulating resin"? As
far as I can tell with the help of Google, there's no such thing.
<https://www.google.com/search?q=electrostatically+insulating+resin>
<https://www.youtube.com/watch?v=Ac7G7xOG2Ag>

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

On Fri, 22 Apr 2022 08:15:28 -0700 (PDT), William Crowell
<retroguybilly@gmail.com> wrote:

>Andrew, is the use of carbon fiber tubes with titanium lugs proven technology? Are the tubes glued to the lugs?

It's not a new technology. Some bicycle examples:
<https://www.google.com/search?q=bicycle+carbon+fiber+titanium+lugs>

See the section on Titanium in:
"Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
Polymers"
<https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
"Therefore, there is no significant gap between titanium and
carbon-fiber-reinforced composite to create galvanic corrosion. This
means that commercially pure titanium and its alloys are completely
resistant to galvanic corrosion when they are coupled with carbon
composites."

More:
<https://www.corrosionpedia.com/search?q=titanium+carbon+fiber>

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

On Fri, 22 Apr 2022 20:46:22 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Fri, 22 Apr 2022 09:52:31 -0700 (PDT), Tom Kunich
><cyclintom@gmail.com> wrote:
>
>>On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
>>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
>>
>>Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.
>
>Perfect score. Everything you've posted today has been wrong.
>
>"Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
>Polymers"
><https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
>"Therefore, there is no significant gap between titanium and
>carbon-fiber-reinforced composite to create galvanic corrosion. This
>means that commercially pure titanium and its alloys are completely
>resistant to galvanic corrosion when they are coupled with carbon
>composites"
>
>Extra credit. What is an "electrostatically insulating resin"? As
>far as I can tell with the help of Google, there's no such thing.
><https://www.google.com/search?q=electrostatically+insulating+resin>
><https://www.youtube.com/watch?v=Ac7G7xOG2Ag>

Well, A carbon fiber/epoxy resin composite conducts electricity
through the carbon fibers and epoxy is used as an insulator (:-)
https://www.twintrackengineeringspares.com/epoxy-insulator.html

However, as rivets are normally driven so tight as to be waterproof
one might think that any "insulating resin" would be squeezed out in
the riveting process (:-)
--
Cheers,

John B.

On Friday, April 22, 2022 at 10:51:48 PM UTC-5, jeff.li...@gmail.com wrote:
> On Fri, 22 Apr 2022 08:15:28 -0700 (PDT), William Crowell
> <retrog...@gmail.com> wrote:
>
> >Andrew, is the use of carbon fiber tubes with titanium lugs proven technology? Are the tubes glued to the lugs?
> It's not a new technology. Some bicycle examples:
> <https://www.google.com/search?q=bicycle+carbon+fiber+titanium+lugs>
>

Alan and Vitus glued carbon tubes to aluminum lugs in the 1970s and 1980s. So metal lugs and carbon tubes glued together have been around for over 40 years.

> See the section on Titanium in:
> "Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
> Polymers"
> <https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
> "Therefore, there is no significant gap between titanium and
> carbon-fiber-reinforced composite to create galvanic corrosion. This
> means that commercially pure titanium and its alloys are completely
> resistant to galvanic corrosion when they are coupled with carbon
> composites."
>
> More:
> <https://www.corrosionpedia.com/search?q=titanium+carbon+fiber>
> --
> Jeff Liebermann je...@cruzio.com
> PO Box 272 http://www.LearnByDestroying.com
> Ben Lomond CA 95005-0272
> Skype: JeffLiebermann AE6KS 831-336-2558

On 4/22/2022 10:46 PM, Jeff Liebermann wrote:
> On Fri, 22 Apr 2022 09:52:31 -0700 (PDT), Tom Kunich
> <cyclintom@gmail.com> wrote:
>
>> On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
>>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
>>
>> Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.
>
> Perfect score. Everything you've posted today has been wrong.
>
> "Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
> Polymers"
> <https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
> "Therefore, there is no significant gap between titanium and
> carbon-fiber-reinforced composite to create galvanic corrosion. This
> means that commercially pure titanium and its alloys are completely
> resistant to galvanic corrosion when they are coupled with carbon
> composites"
>
> Extra credit. What is an "electrostatically insulating resin"? As
> far as I can tell with the help of Google, there's no such thing.
> <https://www.google.com/search?q=electrostatically+insulating+resin>
> <https://www.youtube.com/watch?v=Ac7G7xOG2Ag>
>

The notable bicycle examples were early carbon tubes in cast
aluminum joints.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Saturday, April 23, 2022 at 12:22:53 AM UTC-4, John B. wrote:
> On Fri, 22 Apr 2022 20:46:22 -0700, Jeff Liebermann <je...@cruzio.com>
> wrote:
> >On Fri, 22 Apr 2022 09:52:31 -0700 (PDT), Tom Kunich
> ><cycl...@gmail.com> wrote:
> >
> >>On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
> >>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
> >>
> >>Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.
> >
> >Perfect score. Everything you've posted today has been wrong.
> >
> >"Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
> >Polymers"
> ><https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
> >"Therefore, there is no significant gap between titanium and
> >carbon-fiber-reinforced composite to create galvanic corrosion. This
> >means that commercially pure titanium and its alloys are completely
> >resistant to galvanic corrosion when they are coupled with carbon
> >composites"
> >
> >Extra credit. What is an "electrostatically insulating resin"? As
> >far as I can tell with the help of Google, there's no such thing.
> ><https://www.google.com/search?q=electrostatically+insulating+resin>
> ><https://www.youtube.com/watch?v=Ac7G7xOG2Ag>
> Well, A carbon fiber/epoxy resin composite conducts electricity
> through the carbon fibers and epoxy is used as an insulator (:-)
> https://www.twintrackengineeringspares.com/epoxy-insulator.html
>
> However, as rivets are normally driven so tight as to be waterproof
> one might think that any "insulating resin" would be squeezed out in
> the riveting process (:-)
> --
> Cheers,
>
> John B.
Control of electrostatic energy is a huge issue in my professional area - equipment for use in explosive atmospheres (RE: the IEC 60079 series). Carbon fiber added to composites or plastics doesn't exactly 'conduct' electricity as much as it dissipate as well as prevent the accumulation of charge though triboelectric effects. The one thing you _don't_ want is a rapid discharge such that a spark is created. This is why standards from ESD control of human interactions to equipment for use in explosive atmospheres all have _minimum_ resistance limits, generally on the order of 10^9 ohms. ESD testing is confirmed by the use of VI curves that confirm the slew for rate of the discharge.

I realize the discussion of ESD control is tangential to the point of galvanic reactivity. My point is that carbon fiber based materials will conduct in the context of high resistance to the extent that galvanic corrosion of hybrid materials is a valid concern.

On Saturday, April 23, 2022 at 10:46:11 AM UTC-4, AMuzi wrote:
> On 4/22/2022 10:46 PM, Jeff Liebermann wrote:
> > On Fri, 22 Apr 2022 09:52:31 -0700 (PDT), Tom Kunich
> > <cycl...@gmail.com> wrote:
> >
> >> On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
> >>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
> >>
> >> Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.
> >
> > Perfect score. Everything you've posted today has been wrong.
> >
> > "Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
> > Polymers"
> > <https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
> > "Therefore, there is no significant gap between titanium and
> > carbon-fiber-reinforced composite to create galvanic corrosion. This
> > means that commercially pure titanium and its alloys are completely
> > resistant to galvanic corrosion when they are coupled with carbon
> > composites"
> >
> > Extra credit. What is an "electrostatically insulating resin"? As
> > far as I can tell with the help of Google, there's no such thing.
> > <https://www.google.com/search?q=electrostatically+insulating+resin>
> > <https://www.youtube.com/watch?v=Ac7G7xOG2Ag>
> >
> The notable bicycle examples were early carbon tubes in cast
> aluminum joints.
> --

Specialized made an Allez model like that in the late 80s.

On Friday, April 22, 2022 at 3:41:28 PM UTC-4, Frank Krygowski wrote:
> On 4/22/2022 1:35 PM, Tom Kunich wrote:
> >
> > They are now replacing the old and decrepit B52 engines with commercial grade engines used on commercial jetliners. This leads to the idea that there may be a supersonic B52 in the not too distant future. We HAVE these planes now and it would require nothing more than reinforcing whereas a B2 costs now in the billions per.
> <sigh> No, Tom, we're not going to have supersonic B-52s. There's a lot
> more to supersonic flight than just pushing harder. The aerodynamics are
> very, very different.
>
> Admittedly, the class I took covering supersonic aerodynamics was long,
> long ago. When did you take a course on that subject?
>
> --
> - Frank Krygowski

I went to high school with a kid that insisted NASCAR cars were identical to showroom models,with the exception that the tires were wider. Same concept.

On 4/23/2022 5:36 AM, russellseaton1@yahoo.com wrote:
> On Friday, April 22, 2022 at 10:51:48 PM UTC-5, jeff.li...@gmail.com wrote:
>> On Fri, 22 Apr 2022 08:15:28 -0700 (PDT), William Crowell
>> <retrog...@gmail.com> wrote:
>>
>>> Andrew, is the use of carbon fiber tubes with titanium lugs proven technology? Are the tubes glued to the lugs?
>> It's not a new technology. Some bicycle examples:
>> <https://www.google.com/search?q=bicycle+carbon+fiber+titanium+lugs>
>>
>
> Alan and Vitus glued carbon tubes to aluminum lugs in the 1970s and 1980s. So metal lugs and carbon tubes glued together have been around for over 40 years.

Sorry if I may have asked this before, but: Andrew, what's the long term
record of the early Alan and Vitus frames, with aluminum tubes epoxied
into aluminum lugs? Would such a bike be safe to ride today?

--
- Frank Krygowski

On 4/23/2022 10:02 AM, Frank Krygowski wrote:
> On 4/23/2022 5:36 AM, russellseaton1@yahoo.com wrote:
>> On Friday, April 22, 2022 at 10:51:48 PM UTC-5,
>> jeff.li...@gmail.com wrote:
>>> On Fri, 22 Apr 2022 08:15:28 -0700 (PDT), William Crowell
>>> <retrog...@gmail.com> wrote:
>>>
>>>> Andrew, is the use of carbon fiber tubes with titanium
>>>> lugs proven technology? Are the tubes glued to the lugs?
>>> It's not a new technology. Some bicycle examples:
>>> <https://www.google.com/search?q=bicycle+carbon+fiber+titanium+lugs>
>>>
>>>
>>
>> Alan and Vitus glued carbon tubes to aluminum lugs in the
>> 1970s and 1980s. So metal lugs and carbon tubes glued
>> together have been around for over 40 years.
>
> Sorry if I may have asked this before, but: Andrew, what's
> the long term record of the early Alan and Vitus frames,
> with aluminum tubes epoxied into aluminum lugs? Would such a
> bike be safe to ride today?
>

Probably but not certainly.

First series Alan are threaded tubes with adhesive enhanced
joints into gravity cast lugs. Their failures are primarily
casting voids and resulting cracks. I wasn't in the Alan
business for their later carbon version:
http://www.yellowjersey.org/photosfromthepast/failalan.jpg
so I don't know about threading carbon tube. Anyone know that?
The very early aluminum tube models have had low failure
rates compared to other 50-year-old bicycles:
http://www.yellowjersey.org/photosfromthepast/PEUGEPOX.JPG

Superior aluminum alloys, thixoform process and more
advanced adhesives made the Vitus possible. Those have lower
overall weight, lower failure rates but not zero. I've seen
(and repaired) a few bond failures:
http://www.yellowjersey.org/photosfromthepast/PEUGEPOX.JPG
Haven't seen non-crash casting or tube failures myself.
(similar materials and technology for Radac, Kabuki,
Priz/Litage etc)

Trek and others experienced bond failures and galvanic
corrosion in carbon-aluminum models early on, but after the
first few years achieved similarly low failure rates.

This tangent started if I recall with carbon tube bonded in
titanium. There were several successful examples (Tomac
Raleigh) but I don't recall jointing failures for any of
those.(small volume for all brands together)

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Sat, 23 Apr 2022 07:57:46 -0700 (PDT), James Carrington
<jhcjrx@gmail.com> wrote:

>I realize the discussion of ESD control is tangential to the point of galvanic reactivity. My point is that carbon fiber based materials will conduct in the context of high resistance to the extent that galvanic corrosion of hybrid materials is a valid concern.

Actually, it's quite relevant (to me). A few years ago, there was a
discussion on testing carbon fiber frames for cracks and bubbles. The
bleeding edge inspection technologies of the time were (and still are)
ultrasonic, x-ray, fluorescent dies, and thermal imaging. There was
also some work with acoustic resonance and pressurized helium leak
detectors, but I suspect these were deemed impractical.

My idea was a simple "has anything changed" test, where I would attach
electrical connectors to the major frame tubes and measure the
resistance/conductivity. As the carbon fibers separated or cracked,
the resistance would change. The factory would provide initial
resistance measurements when the frame was new. The owner (or
prospective buyer) would compare the initial resistance measurements
with the current (pun intended) resistance measurements to determine
if anything had changed. Such a test would not provide sufficient
information to perform a repair, but would provide a clue that the
frame is unsafe to ride. The hope was that manufacturers and frame
builders would use resistance as part of a QA procedure. User could
run the test with a simple and cheap multimeter.

I only had one CF frame tube that I was willing to sacrifice. However,
I had some CF sheets and some epoxy glue. CF (without epoxy) has a
conductivity of about 100 Siemens/meter and a sheet resistance of
about 50 ohms per square:
"Review on the Electrical Resistance/Conductivity of Carbon Fiber
Reinforced Polymer"
<https://www.mdpi.com/2076-3417/9/11/2390/htm>
I was seeing large variations in conductivity and resistance with gain
orientation, fiber weave, lay, amount of epoxy, type of CF,
temperature, etc. I was also having trouble obtaining a good
electrical connection to the CF sheets. The problem was that epoxy is
a good insulator and the various layers did not make a good (if any)
electrical connection between the sheets. I decided that this was not
going to be easy and that I didn't have the time or facilities to
continue. So I stopped and gave up. I still think it's a good idea,
but someone else will need to do the work.

While all this doesn't relate directly with galvanic compatibility, it
does provide some interesting possibilities. For example, measuring
the resistance between the titanium glued lugs. The trick will be how
to obtain an electrical connection between the titanium lug and the CF
sheets. Graphite flake doped conductive epoxy is one possibility.
With luck, bicycles of the future will have built in electrical
wiring, CF conductivity sensors, and an alarm circuit to warn the
rider that the frame may not be safe to ride.

Technical FAQ: how to find cracks in carbon frames
<https://www.velonews.com/gear/technical-faq-how-to-find-cracks-in-carbon-frames/>

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

On Saturday, April 23, 2022 at 1:07:25 PM UTC-4, jeff.li...@gmail.com wrote:
> On Sat, 23 Apr 2022 07:57:46 -0700 (PDT), James Carrington
> <jhc...@gmail.com> wrote:
>
> >I realize the discussion of ESD control is tangential to the point of galvanic reactivity. My point is that carbon fiber based materials will conduct in the context of high resistance to the extent that galvanic corrosion of hybrid materials is a valid concern.
> Actually, it's quite relevant (to me). A few years ago, there was a
> discussion on testing carbon fiber frames for cracks and bubbles. The
> bleeding edge inspection technologies of the time were (and still are)
> ultrasonic, x-ray, fluorescent dies, and thermal imaging. There was
> also some work with acoustic resonance and pressurized helium leak
> detectors, but I suspect these were deemed impractical.
>
> My idea was a simple "has anything changed" test, where I would attach
> electrical connectors to the major frame tubes and measure the
> resistance/conductivity. As the carbon fibers separated or cracked,
> the resistance would change. The factory would provide initial
> resistance measurements when the frame was new. The owner (or
> prospective buyer) would compare the initial resistance measurements
> with the current (pun intended) resistance measurements to determine
> if anything had changed. Such a test would not provide sufficient
> information to perform a repair, but would provide a clue that the
> frame is unsafe to ride. The hope was that manufacturers and frame
> builders would use resistance as part of a QA procedure. User could
> run the test with a simple and cheap multimeter.
>
> I only had one CF frame tube that I was willing to sacrifice. However,
> I had some CF sheets and some epoxy glue. CF (without epoxy) has a
> conductivity of about 100 Siemens/meter and a sheet resistance of
> about 50 ohms per square:
> "Review on the Electrical Resistance/Conductivity of Carbon Fiber
> Reinforced Polymer"
> <https://www.mdpi.com/2076-3417/9/11/2390/htm>
> I was seeing large variations in conductivity and resistance with gain
> orientation, fiber weave, lay, amount of epoxy, type of CF,
> temperature, etc. I was also having trouble obtaining a good
> electrical connection to the CF sheets. The problem was that epoxy is
> a good insulator and the various layers did not make a good (if any)
> electrical connection between the sheets. I decided that this was not
> going to be easy and that I didn't have the time or facilities to
> continue. So I stopped and gave up. I still think it's a good idea,
> but someone else will need to do the work.
>
> While all this doesn't relate directly with galvanic compatibility, it
> does provide some interesting possibilities. For example, measuring
> the resistance between the titanium glued lugs. The trick will be how
> to obtain an electrical connection between the titanium lug and the CF
> sheets. Graphite flake doped conductive epoxy is one possibility.
> With luck, bicycles of the future will have built in electrical
> wiring, CF conductivity sensors, and an alarm circuit to warn the
> rider that the frame may not be safe to ride.
>
> Technical FAQ: how to find cracks in carbon frames
> <https://www.velonews.com/gear/technical-faq-how-to-find-cracks-in-carbon-frames/>
> --
> Jeff Liebermann je...@cruzio.com
> PO Box 272 http://www.LearnByDestroying.com
> Ben Lomond CA 95005-0272
> Skype: JeffLiebermann AE6KS 831-336-2558

The MDPI paper seems to imply that the product under test needs to have some intentional design to allow for electrical testing - IOW, inherent variations in standard manufacturing techniques wouldn't reveal enough statistical consistency to use as a QC metric.

On Saturday, April 23, 2022 at 7:46:11 AM UTC-7, AMuzi wrote:
> On 4/22/2022 10:46 PM, Jeff Liebermann wrote:
> > On Fri, 22 Apr 2022 09:52:31 -0700 (PDT), Tom Kunich
> > <cycl...@gmail.com> wrote:
> >
> >> On Friday, April 22, 2022 at 7:41:29 AM UTC-7, AMuzi wrote:
> >>> https://bikerumor.com/colnago-c68-classic-italian-carbon-gravel-all-road-bikes/
> >>
> >> Just as you see around titanium rivets in carbon fiber composites, the two together are galvanically active. I am curious as to why they would try and use such a combination when the aerospace industry does combine the two but are extremely careful not to allow any contact between titanium and carbon fiber and even use electrostatically insulating resins.
> >
> > Perfect score. Everything you've posted today has been wrong.
> >
> > "Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced
> > Polymers"
> > <https://www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556>
> > "Therefore, there is no significant gap between titanium and
> > carbon-fiber-reinforced composite to create galvanic corrosion. This
> > means that commercially pure titanium and its alloys are completely
> > resistant to galvanic corrosion when they are coupled with carbon
> > composites"
> >
> > Extra credit. What is an "electrostatically insulating resin"? As
> > far as I can tell with the help of Google, there's no such thing.
> > <https://www.google.com/search?q=electrostatically+insulating+resin>
> > <https://www.youtube.com/watch?v=Ac7G7xOG2Ag>
> >
> The notable bicycle examples were early carbon tubes in cast
> aluminum joints.

Andrew, those carbon aluminum joint made by Vitus and Alan took a GREAT deal of trouble to make sure to to exclude any water. Even so it is rare to find a surviving member of the Trek group that also used that method. As usual we have Jeff, the Google whiz who tries to tell us that carbon and titanium aren't that far apart on the galvanic charts. As if that makes a difference. Slower corrosion is still corrosion and there are no "pure" titanium fittings. Bottle mounts in particular and wire and downtube lever mounts have ALWAYS shown corrosion on the carbon bikes with titanium fittings I have owned. It causes the finish to lift and cracks around their bases to become visible.

On Sunday, April 24, 2022 at 7:35:58 AM UTC-7, jhc...@gmail.com wrote:
> On Saturday, April 23, 2022 at 1:07:25 PM UTC-4, jeff.li...@gmail.com wrote:
> > On Sat, 23 Apr 2022 07:57:46 -0700 (PDT), James Carrington
> > <jhc...@gmail.com> wrote:
> >
> > >I realize the discussion of ESD control is tangential to the point of galvanic reactivity. My point is that carbon fiber based materials will conduct in the context of high resistance to the extent that galvanic corrosion of hybrid materials is a valid concern.
> > Actually, it's quite relevant (to me). A few years ago, there was a
> > discussion on testing carbon fiber frames for cracks and bubbles. The
> > bleeding edge inspection technologies of the time were (and still are)
> > ultrasonic, x-ray, fluorescent dies, and thermal imaging. There was
> > also some work with acoustic resonance and pressurized helium leak
> > detectors, but I suspect these were deemed impractical.
> >
> > My idea was a simple "has anything changed" test, where I would attach
> > electrical connectors to the major frame tubes and measure the
> > resistance/conductivity. As the carbon fibers separated or cracked,
> > the resistance would change. The factory would provide initial
> > resistance measurements when the frame was new. The owner (or
> > prospective buyer) would compare the initial resistance measurements
> > with the current (pun intended) resistance measurements to determine
> > if anything had changed. Such a test would not provide sufficient
> > information to perform a repair, but would provide a clue that the
> > frame is unsafe to ride. The hope was that manufacturers and frame
> > builders would use resistance as part of a QA procedure. User could
> > run the test with a simple and cheap multimeter.
> >
> > I only had one CF frame tube that I was willing to sacrifice. However,
> > I had some CF sheets and some epoxy glue. CF (without epoxy) has a
> > conductivity of about 100 Siemens/meter and a sheet resistance of
> > about 50 ohms per square:
> > "Review on the Electrical Resistance/Conductivity of Carbon Fiber
> > Reinforced Polymer"
> > <https://www.mdpi.com/2076-3417/9/11/2390/htm>
> > I was seeing large variations in conductivity and resistance with gain
> > orientation, fiber weave, lay, amount of epoxy, type of CF,
> > temperature, etc. I was also having trouble obtaining a good
> > electrical connection to the CF sheets. The problem was that epoxy is
> > a good insulator and the various layers did not make a good (if any)
> > electrical connection between the sheets. I decided that this was not
> > going to be easy and that I didn't have the time or facilities to
> > continue. So I stopped and gave up. I still think it's a good idea,
> > but someone else will need to do the work.
> >
> > While all this doesn't relate directly with galvanic compatibility, it
> > does provide some interesting possibilities. For example, measuring
> > the resistance between the titanium glued lugs. The trick will be how
> > to obtain an electrical connection between the titanium lug and the CF
> > sheets. Graphite flake doped conductive epoxy is one possibility.
> > With luck, bicycles of the future will have built in electrical
> > wiring, CF conductivity sensors, and an alarm circuit to warn the
> > rider that the frame may not be safe to ride.
> >
> > Technical FAQ: how to find cracks in carbon frames
> > <https://www.velonews.com/gear/technical-faq-how-to-find-cracks-in-carbon-frames/>
> > --
> > Jeff Liebermann je...@cruzio.com
> > PO Box 272 http://www.LearnByDestroying.com
> > Ben Lomond CA 95005-0272
> > Skype: JeffLiebermann AE6KS 831-336-2558
> The MDPI paper seems to imply that the product under test needs to have some intentional design to allow for electrical testing - IOW, inherent variations in standard manufacturing techniques wouldn't reveal enough statistical consistency to use as a QC metric.
Corrosion through electrostatic differential isn't the same thing. This occurs on microvolt levels over time. Jeff, who doesn't himself ride bikes, want to tell us all about the things that actual riders have seen and deny them.

On 4/22/2022 8:46 PM, Jeff Liebermann wrote:

<snip>

> Perfect score. Everything you've posted today has been wrong.

?מַה נִּשְׁתַּנָּה, הַלַּיְלָה הַזֶּה מִכָּל הַלֵּילוֹת

On Sunday, April 24, 2022 at 12:15:19 p.m. UTC-4, sms wrote:
> On 4/22/2022 8:46 PM, Jeff Liebermann wrote:
>
> <snip>
> > Perfect score. Everything you've posted today has been wrong.
> ?מַה נִּשְׁתַּנָּה, הַלַּיְלָה הַזֶּה מִכָּל הַלֵּילוֹת
Translation: ?Why is this night different from all the other nights
Cheers

On Saturday, April 23, 2022 at 8:01:38 AM UTC-7, jhc...@gmail.com wrote:
> On Friday, April 22, 2022 at 3:41:28 PM UTC-4, Frank Krygowski wrote:
> > On 4/22/2022 1:35 PM, Tom Kunich wrote:
> > >
> > > They are now replacing the old and decrepit B52 engines with commercial grade engines used on commercial jetliners. This leads to the idea that there may be a supersonic B52 in the not too distant future. We HAVE these planes now and it would require nothing more than reinforcing whereas a B2 costs now in the billions per.
> > <sigh> No, Tom, we're not going to have supersonic B-52s. There's a lot
> > more to supersonic flight than just pushing harder. The aerodynamics are
> > very, very different.
> >
> > Admittedly, the class I took covering supersonic aerodynamics was long,
> > long ago. When did you take a course on that subject?
> >
> > --
> > - Frank Krygowski
> I went to high school with a kid that insisted NASCAR cars were identical to showroom models,with the exception that the tires were wider. Same concept.

That is a very poor model. The area of Mach 0,8 and 1.2 is considered "transonic" and to cross the sound barrier in that regime only requires a strong enough airframe and enough power.

Listening to anything Frank has to say is a mistake. If he could actually do anything he would have rather than standing in front of a class his whole life. As the saying goes "those who can, do, and those who can't, teach" I would not criticize Frank so much but he simply begs for it. It is his complete belief that the ONLY means of gaining knowledge is in a classroom. While doing a job for the government that was NOT turning out well, I got a book on Calculus and taught myself and corrected the problem. Om several occasions I have had projects directed by PhD's totally incorrect. That example being just one.

On Sunday, April 24, 2022 at 9:19:34 AM UTC-7, Sir Ridesalot wrote:
> On Sunday, April 24, 2022 at 12:15:19 p.m. UTC-4, sms wrote:
> > On 4/22/2022 8:46 PM, Jeff Liebermann wrote:
> >
> > <snip>
> > > Perfect score. Everything you've posted today has been wrong.
> > ?מַה נִּשְׁתַּנָּה, הַלַּיְלָה הַזֶּה מִכָּל הַלֵּילוֹת
> Translation: ?Why is this night different from all the other nights

I haven't blocked you like the other group of 5. What I have noticed is that you say things that you appear to know nothing about - often. Would you mind telling us what you did for a living and if you EVER accomplished anything that you can be proud of? I don't care if it was building a hot rod, but have you actually ever accomplished something?