Fork survived, head tube didn't!

Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.

http://www.cyclingnews.com/photos.ph...BikeCrashPhSpt

http://www.cyclingnews.com/photos.ph...ashedBikePhSpt

Rik O'Shea wrote:
Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.

http://www.cyclingnews.com/photos.ph...BikeCrashPhSpt

http://www.cyclingnews.com/photos.ph...ashedBikePhSpt


interesting indeed.

jim beam wrote:
Rik O'Shea wrote:
Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.

http://www.cyclingnews.com/photos.ph...BikeCrashPhSpt


http://www.cyclingnews.com/photos.ph...ashedBikePhSpt



interesting indeed.

wow, a whole day passes and the stupidity contestants don't comment on
how cfrp is "brittle", how it should all be aerospace spec and how it is
in fact satan's spawn.

but how silly of me! to expect sufficient interest in commenting
presumes an interest in the /subject matter/ rather than trying to bleat
ridiculous personal dislike of a random anonymous troll they found on
the interweb. on their employers time no less.

jim beam wrote:

Rik O'Shea wrote:

Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.

http://www.cyclingnews.com/photos.ph...ep07/newport07...

http://www.cyclingnews.com/photos.ph...ep07/newport07...

interesting indeed.

wow, a whole day passes and the stupidity contestants don't comment on
how cfrp is "brittle", how it should all be aerospace spec and how it is
in fact satan's spawn.

Are you suggesting that a metal head tube would have erupted like that
one did? I've never seen the like with any kind of metal frame.

The question remains: was the frame's structural failure a result of
the crash, or the cause?

Chalo

Chalo wrote:
jim beam wrote:
Rik O'Shea wrote:
Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.
http://www.cyclingnews.com/photos.ph...ep07/newport07...
http://www.cyclingnews.com/photos.ph...ep07/newport07...
interesting indeed.
wow, a whole day passes and the stupidity contestants don't comment on
how cfrp is "brittle", how it should all be aerospace spec and how it is
in fact satan's spawn.

Are you suggesting that a metal head tube would have erupted like that
one did? I've never seen the like with any kind of metal frame.

no, the whole frame would completely mangled if it were metal
encountering a force of that magnitude.


The question remains: was the frame's structural failure a result of
the crash, or the cause?

result.

if that material were "brittle", the head tube would have broken its way
out and pieces would have broken from head tube leaving an exit hole
proportional to the size of the steer tube. instead however, we see the
pieces of the head tube are still attached, /and/ fracture consistent
with high energy absorption - so to the crash necessary to brute-force
the steer tube through a breach that is resisting it sufficiently to
re-close itself after exit must have been significant.

bottom line, i'd say this a pretty impressive result. the chumps that
are now stand about having bleated that cfrp is "brittle" must be
looking at this and feeling pretty damned stupid. or they should be -
assuming they ever knew anything about deformation and fracture in the
first place [which they haven't yet].

On Fri, 07 Sep 2007 05:55:45 -0700, jim beam wrote:

Chalo wrote:
jim beam wrote:
Rik O'Shea wrote:
Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.
http://www.cyclingnews.com/photos.ph...ep07/newport07...
http://www.cyclingnews.com/photos.ph...ep07/newport07...
interesting indeed.
wow, a whole day passes and the stupidity contestants don't comment on
how cfrp is "brittle", how it should all be aerospace spec and how it is
in fact satan's spawn.

Are you suggesting that a metal head tube would have erupted like that
one did? I've never seen the like with any kind of metal frame.

no, the whole frame would completely mangled if it were metal
encountering a force of that magnitude.


So, given similar conditions, metal and carbon fiber behave differently.
What is the property (or properties) in respect of which they exhibit
different behavior? Brittleness comes to mind, but you've ruled that out.



The question remains: was the frame's structural failure a result of
the crash, or the cause?

result.

if that material were "brittle", the head tube would have broken its way
out and pieces would have broken from head tube leaving an exit hole
proportional to the size of the steer tube.

This sounds like something out of a Roadrunner cartoon. Coyote runs into
stone wall and leaves a coyote-shaped hole.



instead however, we see the
pieces of the head tube are still attached,

That hardly seems dispositive -- shards of safety glass are held in place
by a plastic layer, but that doesn't mean that the material as a whole
isn't brittle.


/and/ fracture consistent
with high energy absorption - so to the crash necessary to brute-force
the steer tube through a breach that is resisting it sufficiently to
re-close itself after exit must have been significant.

bottom line, i'd say this a pretty impressive result. the chumps that
are now stand about having bleated that cfrp is "brittle" must be
looking at this and feeling pretty damned stupid. or they should be -
assuming they ever knew anything about deformation and fracture in the
first place [which they haven't yet].

jim beam wrote:

bottom line, i'd say this a pretty impressive result. the chumps that
are now stand about having bleated that cfrp is "brittle" must be
looking at this and feeling pretty damned stupid. or they should be -
assuming they ever knew anything about deformation and fracture in the
first place [which they haven't yet].

Eye, mote, beam, "beam".

still me wrote:
On Fri, 07 Sep 2007 05:55:45 -0700, jim beam
wrote:

bottom line, i'd say this a pretty impressive result. the chumps that
are now stand about having bleated that cfrp is "brittle" must be
looking at this and feeling pretty damned stupid. or they should be -
assuming they ever knew anything about deformation and fracture in the
first place [which they haven't yet].

Bottom line - I've never seen a steel frame do that, no matter what
the crash conditions.

it won't - it'll plastically deform and do so at a lower stress level.


CF still sucks.

no it doesn't - on a specific modulus basis, it's about the best
material out there right now.

i don't understand the problem people have with a superior [stronger]
material - just because the deformation mechanism is different.
stronger is better. lighter is better. more fatigue resistant is
better. carbon is impressive on all three counts.

On Sep 6, 5:02 am, Rik O'Shea wrote:
Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.

http://www.cyclingnews.com/photos.ph...ep07/newport07...

http://www.cyclingnews.com/photos.ph...ep07/newport07...

How can a crash destroy the bottom of your head tube outwards? I've
seen stuff like that after casing a bmx or mtb jump landing, but hard
to see how that would happen on a road bike....

/s

On Sep 6, 10:00 am, Scott Gordo wrote:
On Sep 6, 5:02 am, Rik O'Shea wrote:

Interesting crash photos. The fork steering column looks ok, the head
tube is kaput.

http://www.cyclingnews.com/photos.ph...ep07/newport07...

http://www.cyclingnews.com/photos.ph...ep07/newport07...

How can a crash destroy the bottom of your head tube outwards? I've
seen stuff like that after casing a bmx or mtb jump landing, but hard
to see how that would happen on a road bike....

/s

It looks almost like something hit the fork from the left, or the bike
was lying on the ground on its left side and something landed on it.