Failed Dura Ace crank arm...

Ron Ruff said:

Thought some of you might be interested. This is a new model, with
an SRM:

http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=18179

That looks like low mileage from almost no erosion depth of the pedal
shaft on the crank face, and as usual, the break is from standing on
the pedal at the bottom of the stroke. It apparently broke to the
inside (laterally) rather than in bending from high pedaling force on
the down stroke.

Jobst Brandt

[email hidden] wrote (in part):

Quoted message said:

the break is from standing on
the pedal at the bottom of the stroke.

Not quite, Jobst:

According to one of his later posts: "Was going through some traffic
lights as they changed to green and was out of the saddle. Not a full
on sprint.."

Sounds like he was pedaling at the time.

D'ohBoy, picking nits

Ron Ruff said:

Thought some of you might be interested. This is a new model, with an
SRM:
http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=18179

Its a dud. How else would this happen...

Ron Ruff said:

Thought some of you might be interested. This is a new model, with an
SRM:
http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=18179

that pic tells you a ton of info, most important item being that the
chain kept falling into the gap between the outer ring and the crank
arm, so the crank arm's been gouged. once that happens, a fatigue crack
will initiate and grow - it's simply a matter of time. if i were
shimano, i'd not warranty.

I don't think it was caused by chain damage on the inside of
the crank. Based upon the damage profile, the failure
originated on the outer surface of the crank.

jim beam said:

Ron Ruff said:

Thought some of you might be interested. This is a new model, with an
SRM:
http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=18179

that pic tells you a ton of info, most important item being that the
chain kept falling into the gap between the outer ring and the crank
arm, so the crank arm's been gouged. once that happens, a fatigue crack
will initiate and grow - it's simply a matter of time. if i were
shimano, i'd not warranty.

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

Quoted message said:

Thought some of you might be interested. This is a new model, with an
SRM:
http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=18179

Hey, they really are hollow! Pretty thin walls too from what I can see.
Previous to this I've only seen an original LX Hollowtech open.

At least it sounds like SRM/Shimano are doing the right thing.

Skippy
E&OE

Bill S said:

I don't think it was caused by chain damage on the inside of the crank.
Based upon the damage profile, the failure originated on the outer
surface of the crank.

you're right, it certainly failed that way, but it doesn't mean it
initiated there. more pics would be much more informative.

Quoted message said:

jim beam said:

Ron Ruff said:

Thought some of you might be interested. This is a new model, with an
SRM:
http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=18179

that pic tells you a ton of info, most important item being that the
chain kept falling into the gap between the outer ring and the crank
arm, so the crank arm's been gouged. once that happens, a fatigue
crack will initiate and grow - it's simply a matter of time. if i
were shimano, i'd not warranty.

Pete n Gail who? said:

Quoted message said:

... the break is from standing on the pedal at the bottom of the
stroke.

Quoted message said:

Not quite, Jobst:

Quoted message said:

According to one of his later posts: "Was going through some traffic
lights as they changed to green and was out of the saddle. Not a
full on sprint..."

OH! so when sprinting one doesn't stand on the pedal at the bottom of
the stroke as weight is shifted from one leg to the other? I have
never seen anyone who could do such an act of levitation.

Quoted message said:

Sounds like he was pedaling at the time.

Soooooo? Did I say anything about not pedaling?

Quoted message said:

D'ohBoy, picking nits

They are collection in your imagination.

Jobst Brandt

weightweenies.starbike.comviewtopic.phpOpen ↗

Ouch! That spindle is FUBAR.

Quoted post said:

Originally Posted by Alex Spishakoff [IMG]/img/forum/go_quote.gif[/IMG]

http://weightweenies.starbike.com/forum/viewtopic.php?p=973429#p973429

Did you revive both zombie threads on both forums? Are you on a crusade? Ha :-)