105 flange failure pics

This summer I snapped a newish 105 hub flange/shell across 4 spokes.
Take a look

http://freeengineer.org/flangefailure.html

And you guys said pulling spokes on the outside was OK

CRM

cashrefundman wrote:
This summer I snapped a newish 105 hub flange/shell across 4 spokes.
Take a look

http://freeengineer.org/flangefailure.html

And you guys said pulling spokes on the outside was OK

CRM

that's an unusually large chunk of flange you had fail there. what was
your spoke tension?

In article ,
cashrefundman wrote:

This summer I snapped a newish 105 hub flange/shell across 4 spokes.
Take a look

http://freeengineer.org/flangefailure.html

And you guys said pulling spokes on the outside was OK

CRM

That's an interesting failure.

Don't take this the wrong way, but how did you take five pictures of
that failure, and not get one of them where the metal faces were in
focus? Seeing detail on those areas can help the smart guys here
diagnose the failure mode.

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.

cashrefundman wrote in message . ..
This summer I snapped a newish 105 hub flange/shell across 4 spokes.
Take a look

http://freeengineer.org/flangefailure.html

And you guys said pulling spokes on the outside was OK

CRM


That's an impressive failure. FWIW, I'm a bit lighter (probably 250
max total, including bike, me, baggage, etc.) and I have a set of
'new' 105 32h holes with about 8,000 miles on 'em, and I've never had
a problem with them. I assume Shimano warranteed the hub?

jim beam wrote:



that's an unusually large chunk of flange you had fail there. what was
your spoke tension?

Don't know the tension but I built and maintained it to be "pretty
tight" on the drive side.

CRM

Ryan Cousineau wrote:


Don't take this the wrong way, but how did you take five pictures of
that failure, and not get one of them where the metal faces were in
focus?

I tried but my camera is autofocus and won't on that spot.

Seeing detail on those areas can help the smart guys here
diagnose the failure mode.

Well it's just grainy looking cast aluminum. I don't doubt that it is a
fatigue failure.

To me it looks like it started in at the corner of recess where the
freehub body nests into the hub shell (The thinnest part of the hub
shell) and propagated from there to the spoke holes

CRM

cashrefundman wrote:
jim beam wrote:



that's an unusually large chunk of flange you had fail there. what
was your spoke tension?


Don't know the tension but I built and maintained it to be "pretty
tight" on the drive side.

CRM


well, i know there are years of archive "advice" on this forum telling
people to build wheels with spokes as tight as possible, but i'm telling
you this is flawed. excess tension does /not/ improve wheel rigidity,
only spoke & rim modulus do that. excess tension does not improve spoke
fatigue resistance, only the manufacturer of the spokes does that.

what excess spoke tension /does/ achieve is rim cracking and hub flange
failure. if i rebuilt this wheel, i would;

1. use the rim manufacturer's specified spoke tension.
2. use the hub manufacturer's specified spoke lacing pattern.
3. enjoy long & trouble-free service.

imo, this excess spoke tension stuff is probably the single biggest
factor in the rapid rise of the pre-built wheel market. if i were
mavic, and kept being presented with warranty returns for cracked rims
that my lab testing showed to have been built with excess tension, there
would come a point where i would want to control the lunacy. the only
solution is to get into the wheel building market - that way, product
leaving the factory is /known/ to be built to spec. and warranty becomes
managable.

jim beam wrote:
cashrefundman wrote:

Don't know the tension but I built and maintained it to be "pretty
tight" on the drive side.

CRM


well, i know there are years of archive "advice" on this forum telling
people to build wheels with spokes as tight as possible, but i'm telling
you this is flawed. excess tension does /not/ improve wheel rigidity,
only spoke & rim modulus do that. excess tension does not improve spoke
fatigue resistance, only the manufacturer of the spokes does that.

People who have read and understood the years of archived advice from this
forum know that high tension does not improve wheel rigidity and they know
that high tension does not improve spoke fatigue resistance. They also
know that neither of these benefits has ever been claimed. The only
claim is that high tension increases the ultimate strength of the wheel.
This claim has been repeatedly shown to be true. Please explain how this
proven relationship between spoke tension and wheel strength is flawed.


--
Todd Bryan
Santa Barbara, CA
bryan at cs dot utk dot edu

cashrefundman Wrote:
This summer I snapped a newish 105 hub flange/shell across 4 spokes.
Take a look

http://freeengineer.org/flangefailure.html

And you guys said pulling spokes on the outside was OK

CRM

I am glad that you were able to ride home.
36 spokes built in semi-tangential way allowed you the redundancy to do
this.
Phil Wood flanges are very thick and tough, but I think you could use
another Shimano hub without a similar failure.

1. Double Butted spokes help spread the load amongst themselves and
over larger portions of the rim and *HUB*.
2. The hub could have been damaged during the build if the builder
used a spoke head setting tool and hit the hub flange hard enough.
Other damage to the hub flange could have happened, but it doesn't help
to speculate further without more knowledge of this particular hub.
3. Spoke tension balancing is important to have spokes share the load
and the rim/hub interfaces have even load distributio as well.
4. Spoke support angle makes a larger difference as the load
increases. If you can use a wider OLD and/or a rim with OFF CENTER
spoke bead, you can accomplish spreading the load more effectively.
5. Stiffer rims help spread the load over more spokes, and becuase of
this over a larger number of spoke/hub hole interfaces.

Chalo is a very big rider with considerable wheel building and riding
experience.
Now that he is healing from his recent crash, he may add his thoughts.
His suggestions could help even more.


--
daveornee

In article ,
cashrefundman wrote:

Ryan Cousineau wrote:


Don't take this the wrong way, but how did you take five pictures of
that failure, and not get one of them where the metal faces were in
focus?

I tried but my camera is autofocus and won't on that spot.

Dang.

Seeing detail on those areas can help the smart guys here
diagnose the failure mode.

Well it's just grainy looking cast aluminum. I don't doubt that it is a
fatigue failure.

One issue is that you may see two different looks on the broken bits:
one where the tearing initiated slowly, until enough of the part failed
that it breaks the flange section off catastrophically.

To me it looks like it started in at the corner of recess where the
freehub body nests into the hub shell (The thinnest part of the hub
shell) and propagated from there to the spoke holes

Any signs of scratches or other features that might have initiated a
crack in that area?

--
Ryan Cousineau, http://www.wiredcola.com
Verus de parvis; verus de magnis.