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Cracks?!

Started by John Thompson · 15 January 2006 · Last activity 19 January 2006 · 23 posts · 716 views

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01 / Original postCracks?!John Thompson · 15 Jan 2006 02 / This pagePosts 21–23Page 2 of 2 · chronological order 03 / Latest replyPost #23jim beam · 19 Jan 2006

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Original section: Cycling Equipment
Published: 15 January 2006
Last activity: 19 January 2006
Original author: John Thompson
Posts: 23
Discussion status: Public discussion
Total views: 716
Views / 30 days: 0
Topics: Aluminium frames Cranksets Race licensing

The navigation and discussion metadata provide context. Posts remain in their original chronological order.

Jay Beattie
Archived post

18 January 2006, 01:24 UTC #21

"E Goforth" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:
Hello,
I like Zeus stuff, I have a Zeus seatpost bolt that I've

transfered from
Quoted message said:
bike to bike since my first racing bike in the early eighties.

I also
Quoted message said:
think this crack looks superficial
However, I was sprinting out of the saddle about fifteen years

ago and
Quoted message said:
snapped a Super Record crank in half. My crank was one of the

later
Quoted message said:
unfluted ones that was supposed to be stronger than the earlier

ones. I
Quoted message said:
wasn't lucky enough to see the crack in time. It must have

been there.
Quoted message said:
After it broke you could clearly see the lines in the

fracture
Quoted message said:
surface, kind of like the rings on a tree, and then the frosted

looking
Quoted message said:
area where it failed catastrophically. I was in grad school

for
Quoted message said:
mechanical engineering at the time.
I broke my shoulder blade and had to have stitches on my hand,

elbow,
Quoted message said:
shoulder and hip. I was riding on a road that was paved with

asphalt
Quoted message said:
and then had a layer of pea gravel kind of embedded in the

surface. It
Quoted message said:
really did a number on me.
Even though I think you're right and this crack isn't

structural I
Quoted message said:
wouldn't ride on it. I wouldn't take the chance of it breaking

while
Quoted message said:
riding if I were you.
People broke the old NR cranks all the time. I broke three or
four. Jobst broke way more than that. There were characteristic
failure points and crack characteristics. These pictures don't
fit the profile, IMO -- and the Zeus is basically the old NR with
a more angular flute. I would just watch the crank to make sure
the surface defects do not turn in to cracks. Listen for
creaking, too. -- Jay Beattie.

Report
jtaylor
Archived post

18 January 2006, 15:16 UTC #22

"Jay Beattie" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:

"E Goforth" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:
Hello,
I like Zeus stuff, I have a Zeus seatpost bolt that I've

transfered from
Quoted message said:
bike to bike since my first racing bike in the early eighties.

I also
Quoted message said:
think this crack looks superficial
However, I was sprinting out of the saddle about fifteen years

ago and
Quoted message said:
snapped a Super Record crank in half. My crank was one of the

later
Quoted message said:
unfluted ones that was supposed to be stronger than the earlier

ones. I
Quoted message said:
wasn't lucky enough to see the crack in time. It must have

been there.
Quoted message said:
After it broke you could clearly see the lines in the

fracture
Quoted message said:
surface, kind of like the rings on a tree, and then the frosted

looking
Quoted message said:
area where it failed catastrophically. I was in grad school

for
Quoted message said:
mechanical engineering at the time.
I broke my shoulder blade and had to have stitches on my hand,

elbow,
Quoted message said:
shoulder and hip. I was riding on a road that was paved with

asphalt
Quoted message said:
and then had a layer of pea gravel kind of embedded in the

surface. It
Quoted message said:
really did a number on me.
Even though I think you're right and this crack isn't

structural I
Quoted message said:
wouldn't ride on it. I wouldn't take the chance of it breaking

while
Quoted message said:
riding if I were you.
People broke the old NR cranks all the time. I broke three or
four. Jobst broke way more than that. There were characteristic
failure points and crack characteristics. These pictures don't
fit the profile, IMO -- and the Zeus is basically the old NR with
a more angular flute. I would just watch the crank to make sure
the surface defects do not turn in to cracks. Listen for
creaking, too. -- Jay Beattie.
If he's woried about breakage 5 minutes with a dremel (or 20 with a riffler
file) rounding the sharp bits where the arms meet the crank will be good
insurance.

Report
jim beam
Archived post

19 January 2006, 06:11 UTC #23

jtaylor said:
"Jay Beattie" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:
"E Goforth" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:
Hello,
I like Zeus stuff, I have a Zeus seatpost bolt that I've
transfered from
Quoted message said:
bike to bike since my first racing bike in the early eighties.
I also
Quoted message said:
think this crack looks superficial
However, I was sprinting out of the saddle about fifteen years
ago and
Quoted message said:
snapped a Super Record crank in half. My crank was one of the
later
Quoted message said:
unfluted ones that was supposed to be stronger than the earlier
ones. I
Quoted message said:
wasn't lucky enough to see the crack in time. It must have
been there.
Quoted message said:
After it broke you could clearly see the lines in the
fracture
Quoted message said:
surface, kind of like the rings on a tree, and then the frosted
looking
Quoted message said:
area where it failed catastrophically. I was in grad school
for
Quoted message said:
mechanical engineering at the time.
I broke my shoulder blade and had to have stitches on my hand,
elbow,
Quoted message said:
shoulder and hip. I was riding on a road that was paved with
asphalt
Quoted message said:
and then had a layer of pea gravel kind of embedded in the
surface. It
Quoted message said:
really did a number on me.
Even though I think you're right and this crack isn't
structural I
Quoted message said:
wouldn't ride on it. I wouldn't take the chance of it breaking
while
Quoted message said:
riding if I were you.
People broke the old NR cranks all the time. I broke three or
four. Jobst broke way more than that. There were characteristic
failure points and crack characteristics. These pictures don't
fit the profile, IMO -- and the Zeus is basically the old NR with
a more angular flute. I would just watch the crank to make sure
the surface defects do not turn in to cracks. Listen for
creaking, too. -- Jay Beattie.
If he's woried about breakage 5 minutes with a dremel (or 20 with a riffler
file) rounding the sharp bits where the arms meet the crank will be good
insurance.

not that simple - any work needs to be oriented for loading stress, not
what looks pretty. emulation of the profiles/surface orientations used
in modern campy or shimano would help. random smoothing operations will
not, and could make it worse.

Report

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