Yet another broken crank thread

Quoted message said:

http://www.flickr.com/photos/90784314@N00/9040858/
I weigh less 72 kilos and have had these cranks for under one year.

Ride standing up much?

From the look of it, the break started at the points of the ridges and
migrated, which is not surprising. Is there a chance that at the
location of the break there was a nick or heavy scratch on the ridges?
--
Typoes are a feature, not a bug.
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Is it just my imagination, or are the majority of these broken crank
threads about Ritchey cranks?

Quoted message said:

http://www.flickr.com/photos/90784314@N00/9040858/
I weigh less 72 kilos and have had these cranks for under one year.

Looks like that one's been on its way for awhile now.

Hope you're okay.

Got it everyone, wash and inspect once a week. (actually I'm just saying that to
remind myself)

Ron

mugwump said:

Is it just my imagination, or are the majority of these broken crank
threads about Ritchey cranks?

quite possibly. ever wonder why campy & shimano have abandoned this
"i-beam" style of arm? answer: the sharp edges are points of maximum
stress. this increases notch vulnerability. any slight inherent or
aquired flaw is a fatigue nucleator in the maximum stress zone - not a
good combination.

On Tue, 12 Apr 2005 20:27:05 -0700, jim beam <[email hidden]>

Quoted message said:

mugwump said:

Is it just my imagination, or are the majority of these broken crank
threads about Ritchey cranks?

quite possibly. ever wonder why campy & shimano have abandoned this
"i-beam" style of arm? answer: the sharp edges are points of maximum
stress. this increases notch vulnerability. any slight inherent or
aquired flaw is a fatigue nucleator in the maximum stress zone - not a
good combination.

It seems inherently stupid (to me, at least) to be using a relatively
thin-walled *open* section for a member that's loaded in both bending
and torsion.

[email hidden]

Yes. I do a lot of climbing standing. 🙂

re: nick or scratch - I don't see one but it may just be hard to see
after the fact.

There is a crack in the same arm near this break in the next two
pictures. None visible on the right arm as far as I can tell.

Quoted message said:

Yes. I do a lot of climbing standing. 🙂

re: nick or scratch - I don't see one but it may just be hard to see
after the fact.

There is a crack in the same arm near this break in the next two
pictures. None visible on the right arm as far as I can tell.

Sounds like maybe you need stronger cranks, then, and perhaps it's
wise to start watching for cracks no matter what kind you get.

OTOH, if you contact Ritchey's company, they might replace the failed
units. It's worth a phone call in my estimation.

I don't know what Tom Ritchey (and his company) may have in the way of
engineering and materials expertise in-house, but I will note that in
the field of auto racing, parts from suppliers that are of the "racer
turned maker" variety tend to have a much higher failure rate than
those from car makers. OTOH, the Ritchey stuff that I've had (and
still have, for that matter) has been good enough for what *I* do,
which isn't all that strenuous. (No cranks, though.)
--
Typoes are a feature, not a bug.
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