Bike Weight and Climbing Speed.

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.

--
Joy Beeson
joy beeson at centurylink dot net
http://wlweather.net/PAGEJOY/

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.

True. But equally true that just because one couldn't see a defect
doesn't mean that there isn't one.
--
Cheers,

John B.

On Mon, 04 Jan 2021 21:55:58 -0800, Jeff Liebermann
wrote:

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

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.

Yep. However, I never suggested that a bore scope should be used as
the sole method of inspection. It just happens to be a cheap and easy
way to inspect the inside of the tube for damage. The choice between
a zero dollar "tap test", a $10 borescope, or a $250 ultrasound
inspection, is limited by the resources of the owner. If the bicycle
has been in a crash, then the $250 test is probably the right choice.
You have but one life to give for your bicycle ride. However, if it's
just paranoia, suspicion, or preventive maintenance, the borescope is
cheap and easy.

And, I wasn't accusing you of anything. I was only trying to point out
that simple checks might not find all defects.

And, $250 seems like a lot of money, but if you compare it to the cost
of the frame breaking and one breaking a hip as happened to me
(although I fell off the bike didn't break) it could seem a mere
pittance.



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.

Oh, you want conclusive. We'll, there's nothing more conclusive than
a destructive test. Plug up all the holes in the bicycle frame and
apply air pressure. Carbon fiber is very good in compression, but not
so great in tension. I have no idea how much pressure it can survive,
but a number should be available from the manufacturer. Apply
something less that what is required for a catastrophic failure and
look for cracks and bulges in the paint. If there are any internal
imperfections, one should see a "blow out". If air pressure is
insufficient, maybe fill the frame with water or oil and perform a
hydro test. (Hydroforming is how aluminum frames are shaped.) If the
destructive pressure test blows out a tube or a glue joint, thus
precipitating an expensive repair job, the owner should thank the
bicycle gods that he wasn't riding the bicycle when it failed.

Yes, you could "pressure test" the frame but it wouldn't be a valid
test of the entire frame as some sections of the frame will be of
thinner material than others and thus a pressure low enough to NOT
fracture the thin sections may not be sufficient to adequately test
the thicker.

If you are actually interested in Non Destructive Inspection, NDI,
(sometimes's called to as Non Destructive Testing NDT-) of composites
read
https://www.aviationpros.com/home/ar...ection-methods
for some basics.

Apparently it is a very hot subject in the latest aircraft designs as
if the composite fitting breaks you will likely end up with more then
a broken hip :-)
--
Cheers,

John B.

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

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

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.

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?

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

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.

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

On 1/5/2021 1:52 PM, Jeff Liebermann wrote:

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.

Um... buy from a custom frame builder? I'm the guy who bought a tandem
from a custom frame builder, Jim Bradford. Instead of tandem gauge fork
blades, he used fork blades designed for track racing, with 1/3 the wall
thickness. Granted, they lasted for over 25 years, but I was still
hugely disappointed when they suddenly fractured.

Perhaps "buy from a custom frame builder who is honest and who is not
rushing to complete the bike before his honeymoon."


--
- Frank Krygowski

On Tue, 05 Jan 2021 12:12:54 -0600, 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...

Yes they trademarked a term, not a process. The actual process
comprising "optimum compaction" and "low voids" probably dates back to
the Cooper race cars of the 1960's.
--
Cheers,

John B.