Bike Weight and Climbing Speed.

On Tue, 05 Jan 2021 10:52:15 -0800, Jeff Liebermann
wrote:

On Tue, 05 Jan 2021 01:32:46 -0500, Joy Beeson
wrote:

On Tue, 05 Jan 2021 08:22:35 +0700, John B.
wrote:

Thus simply looking at the inside of the tubes with a "bore scope"
really is not really a conclusive check as defects can actually be
inside the body of the structure.

But if a borescope reveals a fatal flaw, there is no need for the
more-expensive test.

If a flaw is found, and the owner decides to have the CF frame
repaired, there's no guarantee that there are no additional defects in
the frame. The problem with visual inspection is that it's
effectiveness is highly dependent on the abilities of the inspector.
In the distant past, I designed marine radios. I could see production
defects with little more than a quick glance. Then, a real inspector
arrived and showed me what I had missed. With a machine inspection,
most of the limitations of the inspector are removed. There is still
some interpretation of the results needed, but it's much less than
what a visual inspection would require. It's like a doctors
diagnosis. Much can be learned by a superficial inspection or probing
with a stethoscope. However, if you want detail and a higher
confidence level, an X-ray, CT scan, blood test, etc is needed.

The problem with any form of testing is that it's really easy to
demonstrate that something is unsafe. All it takes is one minor
defect or potential problem and the bicycle is instantly declared to
be unsafe to ride. However, it's also impossible to demonstrate that
something is 100.0% safe to ride. One can run every test and perform
every manner of inspection, and still not be certain that bicycle is
rideable. Nothing is prefect.

In QA (quality assurance), the standard measurement of that
uncertainty is the AQL (acceptable quality limit):
https://insight-quality.com/what-is-aql-and-what-do-you-need-to-know-about-it/
Basically, it's how many defects a manufacturer is willing to
tolerate, how much inspection is necessary to achieve it, and what
manner of sample size is necessary to obtain a valid AQL percentage.

Ignoring the inevitable debate over what is an acceptable AQL for your
bicycle, I should point out that few production bicycles are inspected
100%. Therefore, besides crash damage, the bicycle owner runs the
risk of riding a shiny new bicycle with built in defects. Want to
lower the risk? Just add $250 to the cost of a new bicycle, buy from
a custom frame builder, or do your own $10 inspection. A borescope
inspection will probably only catch major defects, but it's better
than ignoring the problem or blindly trusting the manufacturer.
Pressurizing the frame and looking for air leaks might be amusing.
It's not a replacement for a proper ultrasound inspection, but it's a
good start.

One idea that I posted to RBT in the distant past was to mold
conductive wires between the CF layers and measure the resistance
(electrical conductivity) between the wires and between the ends of
the tubes. If measured and recorded when the frame is new, any
changes in resistance will indicate cracking or delamination. For an
extreme case, the thin wires should break before the tube collapses.
With a sufficient number of wires, the general location of the defect
could be found. It wouldn't take much to make a measurement. Some
electrical contacts on the surface of the various tubes, a digital
ohmmeter (about $50), an a chart of the resisances when the bicycle
was new.

Carbon fiber conducts electricity. So hook a lead to the top and
another to the bottom and measure the resistance? Of course the
conduction seems to be in the neighborhood of "2 to 3×105 //basal
plane" to quote the reference so that might not work well either :-)
https://www.thoughtco.com/table-of-e...ctivity-608499
--
Cheers,

John B.

On Tuesday, January 5, 2021 at 9:04:23 AM UTC-8, wrote:
On Tuesday, January 5, 2021 at 5:28:20 AM UTC-8, AMuzi wrote:
On 1/5/2021 12:32 AM, Joy Beeson wrote:
On Tue, 05 Jan 2021 08:22:35 +0700, John B.
wrote:

Thus simply looking at the inside of the tubes with a "bore scope"
really is not really a conclusive check as defects can actually be
inside the body of the structure.

But if a borescope reveals a fatal flaw, there is no need for the
more-expensive test.

+1
Do you expect Joe Bike Rider to be able to tell a fatal wrinkle flaw simply by it being there as opposed to it being in a critical area which most people wouldn't even be aware of?

No, particularly since damage to carbon fiber typically involves sheering between carbon layers or some other invisible disturbance of the Matrix. https://nerdist.com/wp-content/uploa...reeves-759.jpg You need ultrasound or x-ray to see that.

There is no spoon. https://www.youtube.com/watch?v=uAXt...l=PabloPARRADO


-- Jay Beattie.

On Wed, 06 Jan 2021 06:34:35 +0700, John B.
wrote:

Carbon fiber conducts electricity. So hook a lead to the top and
another to the bottom and measure the resistance? Of course the
conduction seems to be in the neighborhood of "2 to 3×105 //basal
plane" to quote the reference so that might not work well either :-)
https://www.thoughtco.com/table-of-e...ctivity-608499

Yep. You can buy carbon fiber heaters and carbon fiber floor heating
wires with reasonable resistance values. For floor heating wire,
about 33 ohms/meter. If anything, the conductivity might be too good
and the resulting resistance too low. Some thought to the wire layout
might be required. For CF tubing, the resistance depends on the
amount of overlap on each sheet. The epoxy is an insulator, which is
why I mentioned adding the wire mess between layers. Maybe the wire
mesh is not needed and just the resistances across and down the tube
is sufficient. I'm fairly sure that just attaching electrodes to the
surface of an existing CF bicycle frame is NOT going to work because
the clear coating is an insulator[1]. Anyway, think positive. It you
don't need am easy way to test for CF frame failure, then just shove
some current through the frame and handlebars and you have a way to
stay warm on winter rides.

As always, more tinkering is necessary:

"How to Make a Carbon Fiber Heater"
https://www.youtube.com/watch?v=aJBsiWsz8Ck
About half way through, he shows how to do it with woven cloth.

"DIY Carbon Heated Blanket"
https://www.instructables.com/DIY-carbon-heated-blanket/

"Carbon Fiber Insulated Heater Wire"
https://www.calcoelectric.com/insulated-heater-wires/carbon-fiber-insulated-heater-wire

"12K Heating Carbon Fiber Floor Wire Warm Underfloor Infrared Cable
220V"
https://www.ebay.com/itm/100M-12K-Heating-Carbon-Fiber-Floor-Wire-Warm-Underfloor-Infrared-Cable-220V-33-/183895458760


[1] If the frame was built using CF tubing and aluminum lugs, I think
that just measuring the resistance between lugs just might work.
https://bikerumor-wpengine.netdna-ssl.com/wp-content/uploads/2011/05/swift-exploded-view1.png

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

On Tue, 05 Jan 2021 16:41:08 -0800, Jeff Liebermann
wrote:

On Wed, 06 Jan 2021 06:34:35 +0700, John B.
wrote:

Carbon fiber conducts electricity. So hook a lead to the top and
another to the bottom and measure the resistance? Of course the
conduction seems to be in the neighborhood of "2 to 3×105 //basal
plane" to quote the reference so that might not work well either :-)
https://www.thoughtco.com/table-of-e...ctivity-608499

Yep. You can buy carbon fiber heaters and carbon fiber floor heating
wires with reasonable resistance values. For floor heating wire,
about 33 ohms/meter. If anything, the conductivity might be too good
and the resulting resistance too low. Some thought to the wire layout
might be required. For CF tubing, the resistance depends on the
amount of overlap on each sheet. The epoxy is an insulator, which is
why I mentioned adding the wire mess between layers. Maybe the wire
mesh is not needed and just the resistances across and down the tube
is sufficient. I'm fairly sure that just attaching electrodes to the
surface of an existing CF bicycle frame is NOT going to work because
the clear coating is an insulator[1]. Anyway, think positive. It you
don't need am easy way to test for CF frame failure, then just shove
some current through the frame and handlebars and you have a way to
stay warm on winter rides.

As always, more tinkering is necessary:

"How to Make a Carbon Fiber Heater"
https://www.youtube.com/watch?v=aJBsiWsz8Ck
About half way through, he shows how to do it with woven cloth.

"DIY Carbon Heated Blanket"
https://www.instructables.com/DIY-carbon-heated-blanket/

"Carbon Fiber Insulated Heater Wire"
https://www.calcoelectric.com/insulated-heater-wires/carbon-fiber-insulated-heater-wire

"12K Heating Carbon Fiber Floor Wire Warm Underfloor Infrared Cable
220V"
https://www.ebay.com/itm/100M-12K-Heating-Carbon-Fiber-Floor-Wire-Warm-Underfloor-Infrared-Cable-220V-33-/183895458760


[1] If the frame was built using CF tubing and aluminum lugs, I think
that just measuring the resistance between lugs just might work.
https://bikerumor-wpengine.netdna-ssl.com/wp-content/uploads/2011/05/swift-exploded-view1.png

The solution is simple... just don't buy one of those crappy plastic
bicycles :-)

Added to that most bikes are made in China and as has been decreed
that we must not surrender to the Chinese. Make America Great! Don't
buy a bicycle.
--
Cheers,

John B.

On Tuesday, January 5, 2021 at 10:13:09 AM UTC-8, AMuzi wrote:
On 1/5/2021 11:01 AM, Tom Kunich wrote:
On Monday, January 4, 2021 at 5:22:42 PM UTC-8, John B. wrote:
On Mon, 04 Jan 2021 10:47:14 -0800, Jeff Liebermann
wrote:
On Mon, 4 Jan 2021 10:07:25 -0800 (PST), Tom Kunich
wrote:

`Wrinkles may or may not be a problem. The real problems are voids and you have to have a lot of experience with the position and placement of voids to be able to know whether they are a threat or not. Buying the improper tool - a scope instead of an ultrasonic scanner, makes little sense.

From 2016:

"Why isn’t the bike industry scanning composites for flaws?"
https://www.bikebiz.com/why-isnt-the-bike-industry-scanning-composites-for-flaws/

CT scanning is faster while ultrasound is cheaper. Only £400,000 for
a CT scanner. No clue on the price of an ultrasound scanner. A $10
borescope or endoscope certainly has its limitations, but methinks
sufficient for finding really gross problems. I don't do CF so I
don't know what's involved, but the borescope was rather handy for
inspecting welds and repairs on steel and aluminum frames.

From 2020:

"Ruckus Composites Inspects Thousands of Bikes with One Ultrasonic
Thickness Gage"
https://www.olympus-ims.com/en/insight/ruckus-composites-inspects-thousands-of-bikes-with-one-ultrasonic-thickness-gage/
https://www.olympus-ims.com/en/45mg/
Only $2,400 ea:
https://www.ebay.com/itm/Olympus-Panametrics-45MG-Ultrasonic-Thickness-Gage-w-D7906-SM-Transducer-Gauge-/353320469558
Maybe you can take up a collection among the local CF riders and share
the expense?
One of the problems is that weak points in composite structures are
frequently a matter of various layers of the fabric not being
completely saturated with the adhesive and thus not adhering to the
adjacent layers completely. To completely check the structure you will
require something that can check the entire thickness of the structure
and check it completely with no spots missed as even a tiny point with
lower strength can result in a stress concentration point.

Thus simply looking at the inside of the tubes with a "bore scope"
really is not really a conclusive check as defects can actually be
inside the body of the structure.
--
Cheers,

John B.
Perhaps you should cease showing your vast unknowledge of carbon fiber construction methods? They use "prepreg" which is all uniformly coated with the resin.

In theory.
But just as aluminum sand castings can have serious
structural voids, fiberglas or carbon layups can be done
both well and badly. Trek even owns a trademark on the
acronym 'OCLV':

http://tmsearch.uspto.gov/bin/showfi...805:68wqot.2.1

Which stands for Optimum Compaction Low Void.

Hmm. Not zero voids, just fewer or smaller...
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971
And I've commented before on Trek's construction techniques. Look is built pretty much like the others but with extremely high standards which means that you have to be careful to only buy a Look from a registered Look Dealer because they are supposed to destroy all of the one's that do not meet their strict standards but instead often they are snuck out of the factory and sold as "barely used".

On Wed, 06 Jan 2021 08:05:41 +0700, John B.
wrote:

The solution is simple... just don't buy one of those crappy plastic
bicycles :-)

Added to that most bikes are made in China and as has been decreed
that we must not surrender to the Chinese. Make America Great! Don't
buy a bicycle.

Sigh. Yet another tech discussion that will soon degenerate into a
political discussion. Yes, I know I'm part of the problem but you
don't need to follow my bad example. Make RBT great again. Don't mix
tech and politics.

Also, what do you have against plastic bicycles?
https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch
Soon everyone will be riding cheap molded plastic bicycles that look
something like this:
https://bicycledesign.net/2008/07/a-recycled-plastic-bike/

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

On Tue, 05 Jan 2021 19:11:30 -0800, Jeff Liebermann
wrote:

On Wed, 06 Jan 2021 08:05:41 +0700, John B.
wrote:

The solution is simple... just don't buy one of those crappy plastic
bicycles :-)

Added to that most bikes are made in China and as has been decreed
that we must not surrender to the Chinese. Make America Great! Don't
buy a bicycle.

Sigh. Yet another tech discussion that will soon degenerate into a
political discussion. Yes, I know I'm part of the problem but you
don't need to follow my bad example. Make RBT great again. Don't mix
tech and politics.

Also, what do you have against plastic bicycles?
https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch
Soon everyone will be riding cheap molded plastic bicycles that look
something like this:
https://bicycledesign.net/2008/07/a-recycled-plastic-bike/

I don't have anything against plastic bicycles. I was just using the
term "cheap plastic" as seems to be used in America, or at least as
used by Google. Try it, google on "cheap plastic", I get 1,240,000,000
"hits" :-)

But, being somewhat of a traditionalist I ride steel bikes which have
the added benefit of being something that I can repair myself.
--
Cheers,

John B.

On Wed, 06 Jan 2021 10:35:52 +0700, John B.
wrote:

On Tue, 05 Jan 2021 19:11:30 -0800, Jeff Liebermann
wrote:

On Wed, 06 Jan 2021 08:05:41 +0700, John B.
wrote:

The solution is simple... just don't buy one of those crappy plastic
bicycles :-)

Added to that most bikes are made in China and as has been decreed
that we must not surrender to the Chinese. Make America Great! Don't
buy a bicycle.

Sigh. Yet another tech discussion that will soon degenerate into a
political discussion. Yes, I know I'm part of the problem but you
don't need to follow my bad example. Make RBT great again. Don't mix
tech and politics.

Also, what do you have against plastic bicycles?
https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch
Soon everyone will be riding cheap molded plastic bicycles that look
something like this:
https://bicycledesign.net/2008/07/a-recycled-plastic-bike/

I don't have anything against plastic bicycles. I was just using the
term "cheap plastic" as seems to be used in America, or at least as
used by Google. Try it, google on "cheap plastic", I get 1,240,000,000
"hits" :-)

When wrapped with double quotes, I only get 6,040,000 hits:
https://www.google.com/search?q=%22cheap+plastic%22
If I limit the search to only include "cheap plastic" and "bicycle", I
get 2,480,000 hits:
https://www.google.com/search?q=%22cheap+plastic%22+and+%22bicycle%22
Ok, I give up. In the bicycle world, anything plastic is considered
cheap, and anything cheap must be made of plastic.

But, being somewhat of a traditionalist I ride steel bikes which have
the added benefit of being something that I can repair myself.

Same here. My remaining two bicycles are both steel. The Miyata 610
was professionally straightened. My welding abilities were not good
enough to insure success. Note the rusted area on the left seat stay:
http://www.learnbydestroying.com/jeffl/pics/bicycles/#Miyata-610.JPG
I never got around to painting it. My other bicycle, a Gary Fisher
Tassajara, doesn't (currently) need any work done on the frame:
http://www.learnbydestroying.com/jeffl/pics/bicycles/#Gary-Fisher-Tassajara.JPG


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

On Tue, 05 Jan 2021 22:28:26 -0800, Jeff Liebermann
wrote:

On Wed, 06 Jan 2021 10:35:52 +0700, John B.
wrote:

On Tue, 05 Jan 2021 19:11:30 -0800, Jeff Liebermann
wrote:

On Wed, 06 Jan 2021 08:05:41 +0700, John B.
wrote:

The solution is simple... just don't buy one of those crappy plastic
bicycles :-)

Added to that most bikes are made in China and as has been decreed
that we must not surrender to the Chinese. Make America Great! Don't
buy a bicycle.

Sigh. Yet another tech discussion that will soon degenerate into a
political discussion. Yes, I know I'm part of the problem but you
don't need to follow my bad example. Make RBT great again. Don't mix
tech and politics.

Also, what do you have against plastic bicycles?
https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch
Soon everyone will be riding cheap molded plastic bicycles that look
something like this:
https://bicycledesign.net/2008/07/a-recycled-plastic-bike/

I don't have anything against plastic bicycles. I was just using the
term "cheap plastic" as seems to be used in America, or at least as
used by Google. Try it, google on "cheap plastic", I get 1,240,000,000
"hits" :-)

When wrapped with double quotes, I only get 6,040,000 hits:
https://www.google.com/search?q=%22cheap+plastic%22
If I limit the search to only include "cheap plastic" and "bicycle", I
get 2,480,000 hits:
https://www.google.com/search?q=%22cheap+plastic%22+and+%22bicycle%22
Ok, I give up. In the bicycle world, anything plastic is considered
cheap, and anything cheap must be made of plastic.

But, being somewhat of a traditionalist I ride steel bikes which have
the added benefit of being something that I can repair myself.

Same here. My remaining two bicycles are both steel. The Miyata 610
was professionally straightened. My welding abilities were not good
enough to insure success. Note the rusted area on the left seat stay:
http://www.learnbydestroying.com/jeffl/pics/bicycles/#Miyata-610.JPG
I never got around to painting it. My other bicycle, a Gary Fisher
Tassajara, doesn't (currently) need any work done on the frame:
http://www.learnbydestroying.com/jeffl/pics/bicycles/#Gary-Fisher-Tassajara.JPG

All my bikes are plain old road bikes, two that I bought second hand
at a used bike dealer in Bangkok and then rebuilt and one I built from
tubes and lugs largely as I wanted to see how difficult it really was
to make a bicycle.
--
Cheers,

John B.

On 1/5/2021 9:11 PM, Jeff Liebermann wrote:
On Wed, 06 Jan 2021 08:05:41 +0700, John B.
wrote:

The solution is simple... just don't buy one of those crappy plastic
bicycles :-)

Added to that most bikes are made in China and as has been decreed
that we must not surrender to the Chinese. Make America Great! Don't
buy a bicycle.

Sigh. Yet another tech discussion that will soon degenerate into a
political discussion. Yes, I know I'm part of the problem but you
don't need to follow my bad example. Make RBT great again. Don't mix
tech and politics.

Also, what do you have against plastic bicycles?
https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch
Soon everyone will be riding cheap molded plastic bicycles that look
something like this:
https://bicycledesign.net/2008/07/a-recycled-plastic-bike/


meh. It's been done:
http://copakeauction.com/ws/wp-conte.../05/101a_1.jpg

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