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Columbus Muscle fork: Feedback Please



 
 
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  #1  
Old December 23rd 03, 12:17 PM
Rik O'Shea
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Default Columbus Muscle fork: Feedback Please

(UMTERP) wrote in message ...
Anyone have any experience with this type of fork? I'm thinking of buying one,
but then someone told me they break easily.

Any feedback appreciated.

Thanks,

Dave


The consensus seems to be that carbon forks will last a lifetime (even
longer than steel) if they are not crashed.

From Columbus:
Carbon forks can be long lasting but one has to take care of other
aspects than metal ones.

A fiber composite material has higher mechanical characteristics than
metals (higher tensile strength, higher fatigue life, higher
stiffness) but it has even different behavior due to its
"non-homogeneous nature". This means that the fork project is really a
"critical point" for life span, moreover the final user has to check
the composite fork with attention to different aspects compared to
metal one. In fact, for composite material the areas of coupling with
other parts are critical (headset bearings, stem clamp, gap
cap),composite has different impact behavior so for each shock is
important to check fork, finally composite is sensitive to ambient
agents (solvents, temperature over 90C etc).
--Riccardo Carpinacci
R&D department, Columbus, Cinelli and 3T

From Look:
There is no limitation because carbon has a natural flexibility. It
can be used a hundred years while maintaining the same stiffness.
--Ming Tan
Look Bicycles

From Reynolds:

After considerable testing and thought on the matter we find the
question of "fork life" in terms of time to be a tough question to
answer. Our fatigue testing would indicate that well built composite
forks are far superior to metal forks with cycle counts running
hundreds of thousands of cycles rather than tens of thousands. These
tests are also run at much higher loads than metal forks can withstand
further demonstrating the durability of composite materials. Based
simply on fatigue life a well made and properly installed composite
fork should last virtually indefinitely if the bike is not crashed or
otherwise abused.

Mike Lopez
Reynolds Composites

From Easton:
There are two failure modes that could cause a fork to fail, fatigue
or impact. Questions about life span are really questions about
fatigue life. How many cycles can a fork survive before it is tired
and worn-out? The good news is the fatigue life of carbon fiber is
immensely more than that of metals. While the writer expresses concern
about his carbon fork lasting as long as a metal component, there is
nothing to worry about in terms of fatigue life on a composite fork.

The most likely cause of failure for a composite fork would be impact
damage sustained from crashing. Most of the time any damage to a fork
from a crash will be visible. Cracks can be seen. We would recommend
that the fork be periodically inspected visually at the drop out area
and along the fork legs to look for cracks or depressions in the
material. Any fork that shows signs of cracking should not be ridden
and replaced immediately.

In general terms, a component made from carbon fiber will far out-last
a component made from metal.

John Harrington
Easton Sports
Ads
  #2  
Old December 23rd 03, 06:20 PM
jim beam
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Default Columbus Muscle fork: Feedback Please

excellent!

Rik O'Shea wrote:
(UMTERP) wrote in message ...

Anyone have any experience with this type of fork? I'm thinking of buying one,
but then someone told me they break easily.

Any feedback appreciated.

Thanks,

Dave



The consensus seems to be that carbon forks will last a lifetime (even
longer than steel) if they are not crashed.

From Columbus:
Carbon forks can be long lasting but one has to take care of other
aspects than metal ones.

A fiber composite material has higher mechanical characteristics than
metals (higher tensile strength, higher fatigue life, higher
stiffness) but it has even different behavior due to its
"non-homogeneous nature". This means that the fork project is really a
"critical point" for life span, moreover the final user has to check
the composite fork with attention to different aspects compared to
metal one. In fact, for composite material the areas of coupling with
other parts are critical (headset bearings, stem clamp, gap
cap),composite has different impact behavior so for each shock is
important to check fork, finally composite is sensitive to ambient
agents (solvents, temperature over 90C etc).
--Riccardo Carpinacci
R&D department, Columbus, Cinelli and 3T

From Look:
There is no limitation because carbon has a natural flexibility. It
can be used a hundred years while maintaining the same stiffness.
--Ming Tan
Look Bicycles

From Reynolds:

After considerable testing and thought on the matter we find the
question of "fork life" in terms of time to be a tough question to
answer. Our fatigue testing would indicate that well built composite
forks are far superior to metal forks with cycle counts running
hundreds of thousands of cycles rather than tens of thousands. These
tests are also run at much higher loads than metal forks can withstand
further demonstrating the durability of composite materials. Based
simply on fatigue life a well made and properly installed composite
fork should last virtually indefinitely if the bike is not crashed or
otherwise abused.

Mike Lopez
Reynolds Composites

From Easton:
There are two failure modes that could cause a fork to fail, fatigue
or impact. Questions about life span are really questions about
fatigue life. How many cycles can a fork survive before it is tired
and worn-out? The good news is the fatigue life of carbon fiber is
immensely more than that of metals. While the writer expresses concern
about his carbon fork lasting as long as a metal component, there is
nothing to worry about in terms of fatigue life on a composite fork.

The most likely cause of failure for a composite fork would be impact
damage sustained from crashing. Most of the time any damage to a fork
from a crash will be visible. Cracks can be seen. We would recommend
that the fork be periodically inspected visually at the drop out area
and along the fork legs to look for cracks or depressions in the
material. Any fork that shows signs of cracking should not be ridden
and replaced immediately.

In general terms, a component made from carbon fiber will far out-last
a component made from metal.

John Harrington
Easton Sports


  #4  
Old December 23rd 03, 08:21 PM
Appkiller
external usenet poster
 
Posts: n/a
Default Columbus Muscle fork: Feedback Please

Wait 'til you feel the difference that reticular titanium mesh makes!
Faster than any other fork, with a combination of extreme lateral
stiffness, vertical compliance, and absorption of high frequency road
buzz that create a fork unmatched in its performance!

Listen to the unsolicited testimony from our riders:

"You are just a fred. But if you get this fork, I may not knock you
off your bike as I pass you."

- Fabrizzio Mazzoleni

"Go Fabs, go!"

- Ryan Cousineau

"I wish I could come up with a good troll for this post."

- F. Golightly

"A haiku:

Carbon fork
Titanium mesh
Reticular the ad said
Faster, in my head"

- Carl Fogel

"insert your favorite bizarre rant here"

- That freaky dude who puts up those freaky posts no one understands
(you know who I am talking about)

App
  #6  
Old December 24th 03, 11:42 AM
Rik O'Shea
external usenet poster
 
Posts: n/a
Default Columbus Muscle fork: Feedback Please

(Carl Fogel) wrote in message . com...

Dear Rik,

I think that the original question was whether
these carbon Columbus Muscle Forks "break easily,"
not whether carbon forks in general last a long
time as long as you don't break them in a crash.

That is, what happens if you pop a pair of these
Columbus Muscle Forks in a vise and whack 'em with
a hammer to simulate a crash or wiggle 'em to mimic
ordinary riding stresses? Do the Columbus forks
bust more easily than other brands of carbon forks
or any kind of metal forks?

Like Dave, I appreciate your feedback, which suggests
that carbon forks in general survive ordinary riding
(but don't crash). That may be what Dave wanted to
know, but he might have been wondering if these Columbus
Muscles forks are the Ford Pinto of the carbon fork world,
too thin, too fragile, or somehow badly designed.

Carl Fogel


The following is from
http://www.framebuilding.com/carbon%20forks.htm
although I dont specifically know how it compares to the testing
performed on carbon forks from other manufactures. ASTM standards call
for a load of 170 lbs. applied perpendicular to the steering axis,
both pushing and pulling for 50,000 cycles without failure. The
information below seems to suggest that the Columbus forks exceed
this.

-----------0---------

Columbus carbon forks are produced in accordance with ISO 9000. All
forks are marked and their history can be traced. The tests include
destruction testing and are performed on finished product samples.
They are very seve

* Frontal and side strength test:
A load of 200 N is first applied to the frontal part and then to
the side part of the fork. The flex is measured on each occasion and
this must not exceed a set value.
* Shock Test:
A mass of 250 N is dropped from a height of 430mm on a properly
restrained fork. In order to pass the test the fork must resist
without breakage or residual deformation.
* Static Test:
A load of 200 N is applied to the frontal part for 1 minute. In
order to pass the test the fork must resist without breakage or
deformation.
* Fatigue Test:
During this test an alternate force of +-600 N is applied. In
order to pass this test the fork must resist for 150,000 cycles
without breaking.
  #7  
Old December 24th 03, 08:39 PM
Carl Fogel
external usenet poster
 
Posts: n/a
Default Columbus Muscle fork: Feedback Please

(Rik O'Shea) wrote in message . com...
(Carl Fogel) wrote in message . com...

Dear Rik,

I think that the original question was whether
these carbon Columbus Muscle Forks "break easily,"
not whether carbon forks in general last a long
time as long as you don't break them in a crash.

That is, what happens if you pop a pair of these
Columbus Muscle Forks in a vise and whack 'em with
a hammer to simulate a crash or wiggle 'em to mimic
ordinary riding stresses? Do the Columbus forks
bust more easily than other brands of carbon forks
or any kind of metal forks?

Like Dave, I appreciate your feedback, which suggests
that carbon forks in general survive ordinary riding
(but don't crash). That may be what Dave wanted to
know, but he might have been wondering if these Columbus
Muscles forks are the Ford Pinto of the carbon fork world,
too thin, too fragile, or somehow badly designed.

Carl Fogel


The following is from
http://www.framebuilding.com/carbon%20forks.htm
although I dont specifically know how it compares to the testing
performed on carbon forks from other manufactures. ASTM standards call
for a load of 170 lbs. applied perpendicular to the steering axis,
both pushing and pulling for 50,000 cycles without failure. The
information below seems to suggest that the Columbus forks exceed
this.

-----------0---------

Columbus carbon forks are produced in accordance with ISO 9000. All
forks are marked and their history can be traced. The tests include
destruction testing and are performed on finished product samples.
They are very seve

* Frontal and side strength test:
A load of 200 N is first applied to the frontal part and then to
the side part of the fork. The flex is measured on each occasion and
this must not exceed a set value.
* Shock Test:
A mass of 250 N is dropped from a height of 430mm on a properly
restrained fork. In order to pass the test the fork must resist
without breakage or residual deformation.
* Static Test:
A load of 200 N is applied to the frontal part for 1 minute. In
order to pass the test the fork must resist without breakage or
deformation.
* Fatigue Test:
During this test an alternate force of +-600 N is applied. In
order to pass this test the fork must resist for 150,000 cycles
without breaking.


Dear Rik,

The site that you found seems to be the Columbus
Carbon parts web site:

http://www.framebuilding.com/carbon%20forks.htm

I found it fascinatinng. I'm ignorant about forks
and materials, but I'm wary of what seems like
confused marketing hype:

"Carbon fibre as a material is 4 times more resistant than steel and 8
times more resistant than aluminium. Its versatility and
directionality allows Columbus designers to modulate the section and
form of the fork blades to satisfy all design criteria, without
compromise or limitation. The Columbus composite fork blades have been
realized by overlapping 15 layers of T-700 aerospace carbon fibre and
then covering this externally with a layer of High Modulus Carbon
fibre, which is 20% lighter and 10% more resistant than T-700.
Additionally the full carbon fork, MUSCLE, also includes a special
reticular fabric in titanium called 'Ti Mesh titanium net'. This has a
considerable damping effect on high frequency vibrations within the
fork, such as those produced by irregular ground surfaces. Super
Muscle includes Kevlar and Nickel for improved weight saving while
maintaining strength and shock resistance."

What do they mean by "resistant"? Strength in
compression?

Why use 15 inner layers of inferior T-700 and
only one outer layer of the good stuff, which
is "20% lighter and 10% more resistant"?

(It sounds as if they could use the good stuff
and make a 10% stronger fork that would be 20%
lighter.)

Why does a carbon fork, often claimed to damp
vibration better than metal, need a layer of
metal mesh to damp vibrations?

How does including Kevlar and nickel in the
Super Muscle Fork save weight while maintaining
strength? Isn't nickel a denser and weaker metal
than the titanium used in the plain muscle fork?

(The titanium in the plain Muscle Fork has roughly
8 times nickel's yield strength and 33% more tensile
strength than nickel, a weaker metal that's twice as
dense as titanium--8,800 kg/cubic-meter versus 4,500
kg/cubic-meter:

http://www.simetric.co.uk/si_metals.htm

This density site also lists manure at 400
kg/cubic meter, a figure that may apply to
some of the Columbus site's explanations.)

Apart from such technical mysteries, it still
sounds as if we don't want to crash such forks,
which was the consensus of the experts in your
previous post. I've gathered elsewhere that
severe carbon damage can be invisible to the
naked eye, while metal tends to bend and reveal
its impending failure.

The ISO 9000 "shock test" mentioned on the site
sounds as if a 670-pound weight is dropped 17
inches onto an upright fork.

While surviving this thump sounds impressive,
ordinary BMX and mountain bikes routinely drop
250 pounds onto the front and rear from considerably
more than a foot and a half, so I'm not sure how
well this simulates a fork-damaging crash, which
typically involves the sideways force of ramming
something. Like a leg-bone, a fork resists impacts
from above that would easily break it from the side.

Again, I do appreciate the effort that you put into
finding this Columbus site, which certainly indicates
that the Muscle fork and its big brother both pass
the basic kinds of tests that I was wondering about
and that might be what the original poster wanted
to know--the ISO standard suggests that the Carbon
Muscle fork meets detailed fork standards, so it
ought to be fairly reliable, no matter what the
marketing people are babbling.

So thanks--it's awfully nice of you to cater to
my curiosity by finding that site.

Carl Fogel
  #8  
Old December 25th 03, 09:56 PM
jim beam
external usenet poster
 
Posts: n/a
Default Columbus Muscle fork: Feedback Please

Carl Fogel wrote:
snip

Why does a carbon fork, often claimed to damp
vibration better than metal, need a layer of
metal mesh to damp vibrations?

How does including Kevlar and nickel in the
Super Muscle Fork save weight while maintaining
strength? Isn't nickel a denser and weaker metal
than the titanium used in the plain muscle fork?


good questions! nickel alloys are not necessarily weak, often quite the
reverse, but they are /cheaper/ than ti!!!

to be honest, i have a hard time filtering out any tech from the
marketing with that columbus blurb, but as i understand it, the reason
composites are good for vibration is because the fibers are embedded in
a polymer matrix. the modulus of the polymer is very low and for small
deformation amplitudes, you're riding on polymer, not high modulus graphite.

what a mesh would do is effectively provide a large volume of polymer
between high density layers of graphite fibers and therefore provide a
zone of "insulation" between different regions of the component. so,
provided that "insulation" layer of polymer can be persuaded to remain
intact at high load, and the mesh would hopefully have this effect as
well as separation, then that could be the reason. but for the
definitive answer, you'll need to ask someone with more composites
experience than i.

jb

  #9  
Old December 26th 03, 03:47 AM
Carl Fogel
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Posts: n/a
Default Columbus Muscle fork: Feedback Please

jim beam wrote in message m...
Carl Fogel wrote:
snip

Why does a carbon fork, often claimed to damp
vibration better than metal, need a layer of
metal mesh to damp vibrations?

How does including Kevlar and nickel in the
Super Muscle Fork save weight while maintaining
strength? Isn't nickel a denser and weaker metal
than the titanium used in the plain muscle fork?


good questions! nickel alloys are not necessarily weak, often quite the
reverse, but they are /cheaper/ than ti!!!

to be honest, i have a hard time filtering out any tech from the
marketing with that columbus blurb, but as i understand it, the reason
composites are good for vibration is because the fibers are embedded in
a polymer matrix. the modulus of the polymer is very low and for small
deformation amplitudes, you're riding on polymer, not high modulus graphite.

what a mesh would do is effectively provide a large volume of polymer
between high density layers of graphite fibers and therefore provide a
zone of "insulation" between different regions of the component. so,
provided that "insulation" layer of polymer can be persuaded to remain
intact at high load, and the mesh would hopefully have this effect as
well as separation, then that could be the reason. but for the
definitive answer, you'll need to ask someone with more composites
experience than i.

jb


Dear Jim,

Most of that went over my head (not your fault, I
have lots of clearance).

But the Columbus site seems to say that they use
cheaper nickel mesh (I found "carbon nickel" mentioned)
to make the more expensive version of the fork--which
somehow ends up being lighter than the cheaper
titanium mesh version.

cheaper plain muscle fork = titanium = 380 grams
expensive super muscle fork = nickel-carbon = 340 grams

I browsed a bit more and found this page describing the
Super Muscle Fork further on the same site:

http://www.framebuilding.com/what.htm

"In the fork column, Columbus has inserted Kevlar
layers, which through their ability to resist cuts
and abrasions, reduce the risk of cuts caused by the
clamps of the handlebar stem, which are particularly
sharp."

Again, I'm wary. Perhaps Kevlar resists cutting better
than plain carbon fiber, but I seem recall reading that
Kevlar is usually cut with ordinary scissors--its
virtues do not include any great resistance to cuts.

There must be some prices somewhere, but I didn't find
any when I looked.

Carl Fogel
  #10  
Old December 27th 03, 05:40 AM
jim beam
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Posts: n/a
Default Columbus Muscle fork: Feedback Please

Carl Fogel wrote:
But the Columbus site seems to say that they use
cheaper nickel mesh (I found "carbon nickel" mentioned)
to make the more expensive version of the fork--which
somehow ends up being lighter than the cheaper
titanium mesh version.

cheaper plain muscle fork = titanium = 380 grams
expensive super muscle fork = nickel-carbon = 340 grams


just don't know. some nickel alloys are quite exotic & expensive, but
those are usually for high temperature applications. don't know the
specifics here, and honestly still can't tell you why nickel would be used.


I browsed a bit more and found this page describing the
Super Muscle Fork further on the same site:

http://www.framebuilding.com/what.htm

"In the fork column, Columbus has inserted Kevlar
layers, which through their ability to resist cuts
and abrasions, reduce the risk of cuts caused by the
clamps of the handlebar stem, which are particularly
sharp."

Again, I'm wary. Perhaps Kevlar resists cutting better
than plain carbon fiber, but I seem recall reading that
Kevlar is usually cut with ordinary scissors--its
virtues do not include any great resistance to cuts.


as nicely stated here;

http://plastics.about.com/library/weekly/aa050597.htm

kevlar is used to protect carbon composites against catastrophic
failure, but one of the only two failed carbon handlebars i've seen was
woven with kevlar, so who knows how this is supposed to work in practice.

while looking for that page, i got totally sidetracked by this:

http://www.ideafinder.com/history/inventors/kwolek.htm

do you have any tech-inclined daughters you want to inspire?

jb



 




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