Another Broken Crank

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

Quoted message said:

For those of you keeping track: this was an Ultegra triple, about
six years old and only modest miles (limited use bad weather
commuter/tourer -- maybe 2K per year tops). Fracture about an
inch and a half below the spindle hole -- not at the pedal eye or
the spindle hole. This is my first broken Japanese crank, and I
have been buying Shimano since '75. By the way, no crash
eventhough I was out of the saddle at the time and going pretty
hard. The one-leg ride home was the worst part of the
experience. -- Jay Beattie.

Pictures, we need pictures! Hey, may be it could be added to the "Wheelsmith
collection"....

"bfd" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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

Quoted message said:

For those of you keeping track: this was an Ultegra triple,

about

Quoted message said:

Quoted message said:

six years old and only modest miles (limited use bad weather
commuter/tourer -- maybe 2K per year tops). Fracture about

an

Quoted message said:

Quoted message said:

inch and a half below the spindle hole -- not at the pedal

eye or

Quoted message said:

Quoted message said:

the spindle hole. This is my first broken Japanese crank,

and I

Quoted message said:

Quoted message said:

have been buying Shimano since '75. By the way, no crash
eventhough I was out of the saddle at the time and going

pretty

Quoted message said:

Quoted message said:

hard. The one-leg ride home was the worst part of the
experience. -- Jay Beattie.

Pictures, we need pictures! Hey, may be it could be added to

the "Wheelsmith

Quoted message said:

collection"....

Maybe Carl Fogel could tutor me on how and where to post them (on
Monday). I will disect the crank tonight and take some pictures
with my hokey digital camera. Do not expect Ansel Adams. I
broke a bunch of Campagnolo and a few others, and this is the
first time I have had a break in this spot. -- Jay Beattie.

Jay Beattie said:

"bfd" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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

Quoted message said:

For those of you keeping track: this was an Ultegra triple,

about

Quoted message said:

Quoted message said:

six years old and only modest miles (limited use bad weather
commuter/tourer -- maybe 2K per year tops). Fracture about

an

Quoted message said:

Quoted message said:

inch and a half below the spindle hole -- not at the pedal

eye or

Quoted message said:

Quoted message said:

the spindle hole. This is my first broken Japanese crank,

and I

Quoted message said:

Quoted message said:

have been buying Shimano since '75. By the way, no crash
eventhough I was out of the saddle at the time and going

pretty

Quoted message said:

Quoted message said:

hard. The one-leg ride home was the worst part of the
experience. -- Jay Beattie.

Pictures, we need pictures! Hey, may be it could be added to

the "Wheelsmith

Quoted message said:

collection"....

Maybe Carl Fogel could tutor me on how and where to post them (on
Monday). I will disect the crank tonight and take some pictures
with my hokey digital camera. Do not expect Ansel Adams. I
broke a bunch of Campagnolo and a few others, and this is the
first time I have had a break in this spot. -- Jay Beattie.

Dear Jay,

It's not too tricky.

You take a picture, save it to your computer as a file, and
email it to me as an attachment at [email hidden].

My ISP gives me free space that's otherwise useless, so I
put the picture up there and email you the link.

You tell everyone where to ogle your broken crank, and I
sell popcorn while they argue about which way it cracked and
why.

Samuel Goldwyn

Jay Beattie said:

"bfd" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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

Quoted message said:

For those of you keeping track: this was an Ultegra triple,

about

Quoted message said:

Quoted message said:

six years old and only modest miles (limited use bad weather
commuter/tourer -- maybe 2K per year tops). Fracture about

an

Quoted message said:

Quoted message said:

inch and a half below the spindle hole -- not at the pedal

eye or

Quoted message said:

Quoted message said:

the spindle hole. This is my first broken Japanese crank,

and I

Quoted message said:

Quoted message said:

have been buying Shimano since '75. By the way, no crash
eventhough I was out of the saddle at the time and going

pretty

Quoted message said:

Quoted message said:

hard. The one-leg ride home was the worst part of the
experience. -- Jay Beattie.

Pictures, we need pictures! Hey, may be it could be added to

the "Wheelsmith

Quoted message said:

collection"....

Maybe Carl Fogel could tutor me on how and where to post them (on
Monday). I will disect the crank tonight and take some pictures
with my hokey digital camera. Do not expect Ansel Adams. I
broke a bunch of Campagnolo and a few others, and this is the
first time I have had a break in this spot. -- Jay Beattie.

NEVER put fracture surfaces back together if you wish to preserve the
evidence of why the failure happened.

--
Tom Sherman - Near Rock Island

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Fri, 21 Jan 2005 17:18:52 -0800, "Jay Beattie"
<[email hidden]> wrote:

<snip>

Quoted message said:

Dear Jay,

It's not too tricky.

You take a picture, save it to your computer as a file, and
email it to me as an attachment at [email hidden].

My ISP gives me free space that's otherwise useless, so I
put the picture up there and email you the link.

You tell everyone where to ogle your broken crank, and I
sell popcorn while they argue about which way it cracked and
why.

Samuel Goldwyn

Thanks, Carl. I sent them to Andrew over the weekend (I do not
have usenet at home), and I hope he can post them to his site --
assuming they arrived. There was some problem with sending them.

Anyway, the dissappointing part of this is that the LBS
(Performance, beleive it or not -- there are three in PDX) says
there is a one year warranty on Shimano parts, so I had to buy a
new crank (I suppose I could have just bought an arm, but that
would have meant spending less money). The silver lining is that
they were on sale -- and after using my various discounts, etc.,
the whole Ultegra triple was less than $80. -- Jay Beattie.

Jay Beattie said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Fri, 21 Jan 2005 17:18:52 -0800, "Jay Beattie"
<[email hidden]> wrote:

<snip>

Quoted message said:

Dear Jay,

It's not too tricky.

You take a picture, save it to your computer as a file, and
email it to me as an attachment at [email hidden].

My ISP gives me free space that's otherwise useless, so I
put the picture up there and email you the link.

You tell everyone where to ogle your broken crank, and I
sell popcorn while they argue about which way it cracked and
why.

Samuel Goldwyn

Thanks, Carl. I sent them to Andrew over the weekend (I do not
have usenet at home), and I hope he can post them to his site --
assuming they arrived. There was some problem with sending them.

Anyway, the dissappointing part of this is that the LBS
(Performance, beleive it or not -- there are three in PDX) says
there is a one year warranty on Shimano parts, so I had to buy a
new crank (I suppose I could have just bought an arm, but that
would have meant spending less money). The silver lining is that
they were on sale -- and after using my various discounts, etc.,
the whole Ultegra triple was less than $80. -- Jay Beattie.

Dear Jay,

Andrew? Andrew!

That back-stabber with the wonderful web site and all those
nice pictures outbid me?

You'll never do lunch in this town again!

Please keep me in mind for any future releases.

Herschel Krustofsky

Jay Beattie said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Fri, 21 Jan 2005 17:18:52 -0800, "Jay Beattie"
<[email hidden]> wrote:

<snip>

Quoted message said:

Dear Jay,

It's not too tricky.

You take a picture, save it to your computer as a file, and
email it to me as an attachment at [email hidden].

My ISP gives me free space that's otherwise useless, so I
put the picture up there and email you the link.

You tell everyone where to ogle your broken crank, and I
sell popcorn while they argue about which way it cracked and
why.

Samuel Goldwyn

Thanks, Carl. I sent them to Andrew over the weekend (I do not
have usenet at home), and I hope he can post them to his site --
assuming they arrived. There was some problem with sending them.

Anyway, the dissappointing part of this is that the LBS
(Performance, beleive it or not -- there are three in PDX) says
there is a one year warranty on Shimano parts, so I had to buy a
new crank (I suppose I could have just bought an arm, but that
would have meant spending less money). The silver lining is that
they were on sale -- and after using my various discounts, etc.,
the whole Ultegra triple was less than $80. -- Jay Beattie.

I'm sorry for any confusion but they are here:
http://www.yellowjersey.org/jayscranks.html

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

A very fortunate guy said:

By the way, no crash eventhough I was out of the saddle at the time and going pretty
hard. The one-leg ride home was the worst part of the
experience. -- Jay Beattie.

How did you manage to stay upright? When you were riding out-of-the
-saddle, were you just coasting or stretching?

For me, I didn't have a fighting chance. I went down fast and hard. I
had no idea my crank snapped until afterwards I looked back and saw two
my bike lying in two pieces.

Thanks.

A Muzi said:

Jay Beattie said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Fri, 21 Jan 2005 17:18:52 -0800, "Jay Beattie"
<[email hidden]> wrote:

<snip>

Quoted message said:

Dear Jay,

It's not too tricky.

You take a picture, save it to your computer as a file, and
email it to me as an attachment at [email hidden].

My ISP gives me free space that's otherwise useless, so I
put the picture up there and email you the link.

You tell everyone where to ogle your broken crank, and I
sell popcorn while they argue about which way it cracked and
why.

Samuel Goldwyn

Thanks, Carl. I sent them to Andrew over the weekend (I do not
have usenet at home), and I hope he can post them to his site --
assuming they arrived. There was some problem with sending them.

Anyway, the dissappointing part of this is that the LBS
(Performance, beleive it or not -- there are three in PDX) says
there is a one year warranty on Shimano parts, so I had to buy a
new crank (I suppose I could have just bought an arm, but that
would have meant spending less money). The silver lining is that
they were on sale -- and after using my various discounts, etc.,
the whole Ultegra triple was less than $80. -- Jay Beattie.

I'm sorry for any confusion but they are here:
http://www.yellowjersey.org/jayscranks.html

1. this is a very high mileage component judging by other general
surface condition features. one should be on constant lookout for any
evidence of cracking in this situation.

2. looks like the constant scuffing & scraping of a badly adjusted shoe
caused this one. there is some significant re-profiling going on there!

3. the >50% fatigue propagation before brittle failure indicates again
that this is a high mileage component that was not particularly
over-stressed in use.

it's interesting that the crack propagated through the root of the
hollow section. material removal/scratching on the outside + location
of change of internal stress profile = propensity to fatigue. note
however that the crack started on the /outside/ of the arm, so in the
absence of condition 2, it's likely this crank would have seen much
longer service.

in general, the longer an aluminum component is in service, the closer
it gets to the end of its "flying hours". preemptive replacement should
always be considered. take advantage of sales & "stock up"
occasionally. also, make sure your equipment is correctly adjusted.
there's no way i could ride with my shoe scuffing the crank arm like
that - it would drive me nuts. doesn't do much for the shoe either.
taking care of basic stuff like this reduces risk of injury & saves
money by reducing premature failure.

"Sir, It's Just Me" <nospam?@thanks?.?> wrote in message
news:[email hidden]...

Quoted message said:

A very fortunate guy said:

By the way, no crash eventhough I was out of the saddle at

the time and going pretty

Quoted message said:

Quoted message said:

hard. The one-leg ride home was the worst part of the
experience. -- Jay Beattie.

How did you manage to stay upright? When you were riding

out-of-the

Quoted message said:

-saddle, were you just coasting or stretching?

For me, I didn't have a fighting chance. I went down fast and

hard. I

Quoted message said:

had no idea my crank snapped until afterwards I looked back and

saw two

Quoted message said:

my bike lying in two pieces.

I was pedalling up a slight grade -- not that fast, maybe 15-18
mph at night in a gravel filled bike lane (left over from a
recent ice storm). This is at least my sixth broken crank
(Ofmega, Stronglight and Campy NR x3 -- there may have been
otheres, but who keeps track). I had a big wobble and thought I
was going down, but I managed tp stay upright (probably because
I did not want to crash for the third time in six weeks -- I just
got the stitches out of my face from the last crash. It has been
a very bad winter). None of my prior crank failures resulted in a
crash, either. If I had been in a turn, or on grossly uneven
road, the result might have been different. -- Jay Beattie.

Jobst Brandt said:

...
For those who have not had a crank fail, this may seem remote and non
threatening, but a bit of visualization could make that different.
When a crank fails, it most often occurs while standing, and if it
occurs at more than about 10mph, the rider falls to the side of the
failure. When adjacent to motor traffic this can be fatal. Crank
failure puts the rider in the position of trying to run with one leg
wile having a bicycle between his legs. It does not work unless speed
is near walking. I have avoided crashing by one footed running on a
few incidents that occurred when starting from a stop light.

Do the pedal and crank "stump" generally stay attached to the rider's
shoe during crank failure when either clips and straps or "clipless"
retention systems are being used?

--
Tom Sherman - Earth

Quoted message said:

Shimano proudly replied to my mail recently that they have never
accepted design information from outside the company. They don't even
want to know well known solutions to old problems that are a mystery
to the bicycle industry but solved elsewhere. Ugh!

Which is a way of saying that they don't pay licence fees, hence no
Aheadsets etc. It has never stopped them from copying designs

---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Marten Gerritsen said:

Quoted message said:

Shimano proudly replied to my mail recently that they have never
accepted design information from outside the company. They don't even
want to know well known solutions to old problems that are a mystery
to the bicycle industry but solved elsewhere. Ugh!

Which is a way of saying that they don't pay licence fees, hence no
Aheadsets etc. It has never stopped them from copying designs

Paying someone such as Jobst Brandt normal hourly fees for consulting
would be an insignificant drop in the bucket of Shimano's R&D budget.

--
Tom Sherman - Earth

Tom Sherman said:

Paying someone such as Jobst Brandt normal hourly fees for consulting
would be an insignificant drop in the bucket of Shimano's R&D budget.

Engineering? I hear those Indian dudes are pretty good at math and stuff. Plus
my buddy who's a bike racer just got done with engineering at San Diego State.
He could really use the cash, dude, an' I'm sure he could do that [censored]...

Matt O.

On Wed, 26 Jan 2005 09:38:06 -0600, Tim McNamara
<[email hidden]> wrote:

[snip]

Quoted message said:

Lots more than
"two" cranks have failed and have been discussed in rec.bikes.tech.

[snip]

Dear Tim,

What would you estimate is the failure rate per ten thousand
cranks sold for all reasons within five years?

Do you know of any dealers who mention figures?

Carl Fogel

In article <[email hidden]>,

Tom Sherman said:

Jobst Brandt said:

...
For those who have not had a crank fail, this may seem remote and non
threatening, but a bit of visualization could make that different.
When a crank fails, it most often occurs while standing, and if it
occurs at more than about 10mph, the rider falls to the side of the
failure. When adjacent to motor traffic this can be fatal. Crank
failure puts the rider in the position of trying to run with one leg
wile having a bicycle between his legs. It does not work unless speed
is near walking. I have avoided crashing by one footed running on a
few incidents that occurred when starting from a stop light.

Do the pedal and crank "stump" generally stay attached to the rider's
shoe during crank failure when either clips and straps or "clipless"
retention systems are being used?

Toeclips & straps do stay on. I was able just to "slide" the bottom of
the pedal on the pavement by stiffening my leg. Fortunately I was going
pretty slow, standing on the pedals, cranking up a steep hill, when my
left crank broke. Didn't crash, but it was pretty scary. If the road
had been rougher I probably wouldn't have been able to do this. It may
have helped that I had a full touring load. That might have limited
my leg's sliding back.

-frank
--

jim beam said:

A Muzi said:

. . . they are here:
http://www.yellowjersey.org/jayscranks.html

[snip]

Quoted message said:

3. the >50% fatigue propagation before brittle failure indicates again
that this is a high mileage component that was not particularly
over-stressed in use.

it's interesting that the crack propagated through the root of the
hollow section. material removal/scratching on the outside + location
of change of internal stress profile = propensity to fatigue. note
however that the crack started on the /outside/ of the arm, so in the
absence of condition 2, it's likely this crank would have seen much
longer service.

[snip]

Dear Jim,

A mechanic once explained to me that cracks in aircraft
panels were sometimes "fixed" by drilling a hole in the end
of the crack--the comparatively big round hole spread the
stress that had been concentrated in the tip of the crack.

Did the big, smooth hollow increase the lifespan of the
crank?

That is, would a solid crank have failed sooner because the
crack would have gone right through instead of having to
spread around?

In one of the pictures, it looks as if the darkened area of
the slow, old crack had to get past the hollow and then
spread back in toward the center on both sides.

Curiously,

Carl Fogel

Tom Sherman said:

Marten Gerritsen said:

Quoted message said:

Shimano proudly replied to my mail recently that they have never
accepted design information from outside the company. They don't even
want to know well known solutions to old problems that are a mystery
to the bicycle industry but solved elsewhere. Ugh!

Which is a way of saying that they don't pay licence fees, hence no
Aheadsets etc. It has never stopped them from copying designs

Paying someone such as Jobst Brandt normal hourly fees for consulting
would be an insignificant drop in the bucket of Shimano's R&D budget.

NIH

Ron

Quoted message said:

jim beam said:

A Muzi said:

. . . they are here:
http://www.yellowjersey.org/jayscranks.html

[snip]

Quoted message said:

3. the >50% fatigue propagation before brittle failure indicates again
that this is a high mileage component that was not particularly
over-stressed in use.

it's interesting that the crack propagated through the root of the
hollow section. material removal/scratching on the outside + location
of change of internal stress profile = propensity to fatigue. note
however that the crack started on the /outside/ of the arm, so in the
absence of condition 2, it's likely this crank would have seen much
longer service.

[snip]

Dear Jim,

A mechanic once explained to me that cracks in aircraft
panels were sometimes "fixed" by drilling a hole in the end
of the crack--the comparatively big round hole spread the
stress that had been concentrated in the tip of the crack.

Did the big, smooth hollow increase the lifespan of the
crank?

good question! not in this case - the hole drill trick only works if
the orientation is the same as the crack tip. in this case, the hole is
transverse to the crack, so it just propagates around it. not something
to try at home incidentally. hole needs to be the right size,
orientation, & for best effect, in steel.

Quoted message said:

That is, would a solid crank have failed sooner because the
crack would have gone right through instead of having to
spread around?

another very good question! solids allow full crack propagation. voids
can, if oriented just so, diffuse the stress sufficiently to arrest
cracks, as above. in this case, there is still a continuous crack
propagation route. i honestly don't know how the two compare in crack
growth rates. my guess is that the solid would be the faster cracker,
but the only definitive method of knowing for sure is testing. some of
the math for fracture propagation is still argued about after a century
of research, and is typically structured for much simpler geometries
than we see here, so no back-of-the-envelopes i'm afraid.

Quoted message said:

In one of the pictures, it looks as if the darkened area of
the slow, old crack had to get past the hollow and then
spread back in toward the center on both sides.

yes indeed. to be honest, i would have expected that effect to be a
little more pronounced.

Quoted message said:

Curiously,

Carl Fogel