Physics lesson

On 5/12/2014 10:23 AM, jbeattie wrote:

So Steve, on what do you base your comment that CF forks fail "a lot."

The large number of manufacturer recalls due to defective CF forks.
Actually the recalls help reduce the number of failures since a recall
is done after a few failures. Use http://www.saferproducts.gov/ to do
a search.

I get the sense that they don't fail a lot in Oregon, because I've only defended a couple CF fork cases, and I represent some big manufacturers state-wide.

The number of CF cases that you defend has little correlation to the
number of broken CF forks.

On 13/05/14 07:09, sms wrote:
On 5/12/2014 10:23 AM, jbeattie wrote:

So Steve, on what do you base your comment that CF forks fail "a lot."

The large number of manufacturer recalls due to defective CF forks.
Actually the recalls help reduce the number of failures since a recall
is done after a few failures. Use http://www.saferproducts.gov/ to do
a search.

I get the sense that they don't fail a lot in Oregon, because I've
only defended a couple CF fork cases, and I represent some big
manufacturers state-wide.

The number of CF cases that you defend has little correlation to the
number of broken CF forks.


I went to http://www.bustedcarbon.com/

(broken seat post)

"Anyway, my contribution is nothing overly dramatic as some of the
entries are by any means but it’s still busted carbon. This shot is of a
friend’s seat post sometime after he adjusted the saddle height. My
guess is the possible over-torque of the clamp at the old height. Just a
guess; either way, it failed."

Yup, over tightening a clamp on a CF tube will damage them. That's made
pretty clear by the number of maximum torque specs printed on bike parts
now.

(broken frame and fork)
"after incident with a car at 35mph my bike is in pieces an I have
multiple broken bones as result"

A metal frame would most likely have bent and been destroyed, speaking
from experience of bumping into a few cars at much lower speed.

(broken fork)
"Vodka bottle got jammed somehow between the blades or something while I
was driving fast as I could from liquer store to home here in Finland.
Carrying the bottle in some sag while driving from lower position. Note
to self: Don't ever do that again. Somewho I survived with only 4
stitches on chin."

Note, don't carry a bag on the handlebars that can swing into the front
wheel. Metal forks are likely to have bent and the rider still crashed.

Visiting the guy who built my frame, he had a shed full of broken metal
frame parts that he'd dissected to establish the mode of failure, and
whether the construction played a part.

I retired a CF fork from my racing bike after over 10 years. Giant
blades. There were cracks in the paint where the blades are glued into
the Al crown. I put them on another bike that I ride from time to time.
I think there's a little more elasticity in the glue than the paint
allows for.

I had another fork on the old racing bike for a few years, then sold it
to a mate who's crashed it twice but the forks are still fine.

My current road bike has CF forks on the steel frame. Works a treat.
No fork breakage for me. But I avoid running into cars and potholes and
swinging liqueur bottles into the front wheel while riding. Maybe
others are not so clever.

CF works fine as a material for making bicycles.

--
JS

On 5/12/2014 3:30 PM, James wrote:
On 13/05/14 07:09, sms wrote:
On 5/12/2014 10:23 AM, jbeattie wrote:

So Steve, on what do you base your comment that CF forks fail "a lot."

The large number of manufacturer recalls due to defective CF forks.
Actually the recalls help reduce the number of failures since a recall
is done after a few failures. Use http://www.saferproducts.gov/ to do
a search.

I get the sense that they don't fail a lot in Oregon, because I've
only defended a couple CF fork cases, and I represent some big
manufacturers state-wide.

The number of CF cases that you defend has little correlation to the
number of broken CF forks.


I went to http://www.bustedcarbon.com/

The problem with that web site is that it's just anecdotal evidence.

When a recall is instituted, whether mandated or voluntary, it's because
it's been determined that there's a problem with the design or
manufacturing of the product in question.

On Mon, 12 May 2014 07:24:10 -0500, AMuzi wrote:

On 5/12/2014 5:54 AM, John B. wrote:
On Sun, 11 May 2014 23:17:02 -0700 (PDT), Dan O
wrote:

On Sunday, May 11, 2014 10:41:17 AM UTC-7, Dan O wrote:
On Friday, May 9, 2014 4:25:38 PM UTC-7, jbeattie wrote:

snip

http://www.channel3000.com/news/bicy...ident/25893480

Hmm... Shaina doesn't say she witnessed the crash - just that it's
out in front of her apartment.


More comments: "we saw it happen. no red light at that intersection,
no cones warning cyclists of the giant crack in the road"

Still not definitive, but "giant crack" sounds more like a fork
breaker than a front wheel grabber.

Is the implication here that a bicyclist requires some sort of notice
about road conditions? After all, a "construction zone" is sort of
under construction and one might expect somewhat less then pristine
road conditions.


OK I'm with you generally. On to specifics.

Except in 2014 E Johnson, a major one-way arterial, is
pocked so badly the the orange cones start by my friend's
house at 100 east and goes all the way out to 1400 east with
traffic pinched to one lane. The usual pace of road repairs
inches along. There are deep utility trenches, not so deep
slits, piles of materials, various equipment and general
obstruction beyond the cones.

I wouldn't tell a cyclist where or how to ride but my choice
of route is parallel on a paved street.

This is a file photo not actually Johnson street:
http://madisoneast.channel3000.com/n...reconstruction

This shows the area:
http://www.cityofmadison.com/enginee...johnsonMap.jpg

My point, although unspoken, was that in reality, one is responsible
to determine the quality of the pathway over which one travels. If the
road is really bad perhaps one should get off and walk, crawl, or
whatever is necessary to avoid crashing.

Blaming a crash on a crack in the road appears to be avoiding
responsibility for one's own actions.
--
Cheers,

John B.
(invalid to gmail)

On Mon, 12 May 2014 08:46:33 -0700, sms
wrote:

On 5/9/2014 4:25 PM, jbeattie wrote:

snip

The comment by police that the broken fork caused the accident is very typical. Riders have wall impacts or catch a stick in their forks, get ejected and wake to find a broken CF fork. As a result of head injury or poor reasoning skills, they immediately conclude that the broken fork caused their fall. In the course of representing manufacturers, I have seen very few forks of any design that simply fell apart during normal use. It happens, but it is very rare.

They fail a lot but it's usually a latent defect or a design issue that
doesn't become apparent until the fork is stressed. So while it isn't
accurate to say that the broken fork cause the crash it's probably
accurate to say that the rough road caused the broken fork. He would
likely have crashed even if the fork hadn't broken if the wheel got
caught in a crack in the pavement. If he just hit a bump and the fork
broke as a result (which is common with CF forks) then that's another story.

CF doesn't require a very high force to cause a failure, and you get
fatigue from relatively low forces. There's a good article about carbon
fiber forks he
https://web.archive.org/web/20100531033826/http://www.rivbike.com/products/show/carbonoms-fork/50-718.
Unfortunately the replacement program has ended.

You are pointing to an article obviously written by someone who knows
very little about the subject.

The fact is that carbon fiber devices can be monitored for damage
caused by cyclic loading (simple description) by measuring the
electrical resistance of the device.

See Journal of Materials Science 33 (1998), Early fatigue damage in
carbon-fibre composites observed by electrical resistance measurement,
by S.Wang, X. Shui, X. Fu and D.D.L. Chung of the
Composite Materials Research Laboratory, State University of New York.
--
Cheers,

John B.
(invalid to gmail)

On Mon, 12 May 2014 11:09:54 +0000 (UTC), Duane
wrote:

John B. wrote:
On Sun, 11 May 2014 23:17:02 -0700 (PDT), Dan O
wrote:

On Sunday, May 11, 2014 10:41:17 AM UTC-7, Dan O wrote:
On Friday, May 9, 2014 4:25:38 PM UTC-7, jbeattie wrote:

snip

http://www.channel3000.com/news/bicy...ident/25893480

Hmm... Shaina doesn't say she witnessed the crash - just that it's
out in front of her apartment.


More comments: "we saw it happen. no red light at that intersection,
no cones warning cyclists of the giant crack in the road"

Still not definitive, but "giant crack" sounds more like a fork
breaker than a front wheel grabber.

Is the implication here that a bicyclist requires some sort of notice
about road conditions? After all, a "construction zone" is sort of
under construction and one might expect somewhat less then pristine
road conditions.

--
Cheers,


Sometime the whole city is a construction zone. Two cyclists in recent
weeks hit by flatbread trucks used to transport cranes. Two separate
incidents. One dead and one critical.

We have cracks in roads bad enough to take down cyclists without any
construction zone.

If there are cracks in the road large enough to cause a cyclist to
crash wouldn't it be better to either go another way, or in extreme,
get off and push?
--
Cheers,

John B.
(invalid to gmail)

On Mon, 12 May 2014 14:09:25 -0700, sms
wrote:

On 5/12/2014 10:23 AM, jbeattie wrote:

So Steve, on what do you base your comment that CF forks fail "a lot."

The large number of manufacturer recalls due to defective CF forks.
Actually the recalls help reduce the number of failures since a recall
is done after a few failures. Use http://www.saferproducts.gov/ to do
a search.

I get the sense that they don't fail a lot in Oregon, because I've only defended a couple CF fork cases, and I represent some big manufacturers state-wide.

The number of CF cases that you defend has little correlation to the
number of broken CF forks.

I think that you have a very tenuous grasp on reality.

The "other guy" certainly implies that he is retained by some bicycle
makers. My experience in a company that retained legal assistance was
that every case that, in the wildest imagination, could have been
determined as liability on the part of the company was handed straight
across to the Legal Beagle.

Thus the number of cases that the Legal Guy has handled is certainly a
good indication of the number of failures that are occurring.
--
Cheers,

John B.
(invalid to gmail)

On 13/05/14 10:39, John B. wrote:
On Mon, 12 May 2014 08:46:33 -0700, sms
wrote:

On 5/9/2014 4:25 PM, jbeattie wrote:

snip

The comment by police that the broken fork caused the accident is very typical. Riders have wall impacts or catch a stick in their forks, get ejected and wake to find a broken CF fork. As a result of head injury or poor reasoning skills, they immediately conclude that the broken fork caused their fall. In the course of representing manufacturers, I have seen very few forks of any design that simply fell apart during normal use. It happens, but it is very rare.

They fail a lot but it's usually a latent defect or a design issue that
doesn't become apparent until the fork is stressed. So while it isn't
accurate to say that the broken fork cause the crash it's probably
accurate to say that the rough road caused the broken fork. He would
likely have crashed even if the fork hadn't broken if the wheel got
caught in a crack in the pavement. If he just hit a bump and the fork
broke as a result (which is common with CF forks) then that's another story.

CF doesn't require a very high force to cause a failure, and you get
fatigue from relatively low forces. There's a good article about carbon
fiber forks he
https://web.archive.org/web/20100531033826/http://www.rivbike.com/products/show/carbonoms-fork/50-718.
Unfortunately the replacement program has ended.

You are pointing to an article obviously written by someone who knows
very little about the subject.

The fact is that carbon fiber devices can be monitored for damage
caused by cyclic loading (simple description) by measuring the
electrical resistance of the device.

See Journal of Materials Science 33 (1998), Early fatigue damage in
carbon-fibre composites observed by electrical resistance measurement,
by S.Wang, X. Shui, X. Fu and D.D.L. Chung of the
Composite Materials Research Laboratory, State University of New York.

It would be nice if the manufacturers of CF parts would embed metal
plates so we could run the multimeter over various points and detect if
our fibres were damaged or not.

Better still, embed a microprocessor to provide real time condition
monitoring of the entire structure.

--
JS

On Mon, 12 May 2014 15:36:02 -0700, sms
wrote:

On 5/12/2014 3:30 PM, James wrote:
On 13/05/14 07:09, sms wrote:
On 5/12/2014 10:23 AM, jbeattie wrote:

So Steve, on what do you base your comment that CF forks fail "a lot."

The large number of manufacturer recalls due to defective CF forks.
Actually the recalls help reduce the number of failures since a recall
is done after a few failures. Use http://www.saferproducts.gov/ to do
a search.

I get the sense that they don't fail a lot in Oregon, because I've
only defended a couple CF fork cases, and I represent some big
manufacturers state-wide.

The number of CF cases that you defend has little correlation to the
number of broken CF forks.


I went to http://www.bustedcarbon.com/

The problem with that web site is that it's just anecdotal evidence.

When a recall is instituted, whether mandated or voluntary, it's because
it's been determined that there's a problem with the design or
manufacturing of the product in question.

I suggest that again you don't know what you are talking about.

Recalls are usually instituted in an effort to preclude liability
claims against the company. If, in the wildest imagination, there
could be a claim against the company then the company will institute a
recall. And, I would imagine that these "recalls" are far more common
in the U.S. then in other countries.

My wife recently got a letter from Honda asking her to bring her car
in to "up date the transmission software". In the U.S. this would
likely have been proceeded by a news story "Honda Recall".

I recently saw a "recall" for a baby seat that fitted in a car. The
recall stated that they had sold over a thousand seats and none had
failed to date "but please bring it in so we can check it".
--
Cheers,

John B.
(invalid to gmail)

On 5/12/2014 5:51 PM, John B. wrote:

snip

Thus the number of cases that the Legal Guy has handled is certainly a
good indication of the number of failures that are occurring.

Your mistake is in assuming that every CF fork failure (or any
material's fork failure) resulted in injuries, and that even if injuries
resulted that those injuries prompted a lawsuit.

I'm sure that Jay would tell you the same thing, that a) not everyone
who has a fork fail gets injured, b) not everyone is injured to the
point where they sue for injuries, c) if they do sue for injuries most
claims are settled without a court case. As in most industries, most
cases are settled quietly with no publicity. It's rarely in anyone's
interest to have a protracted legal battle.