Dear Steve,
Ron is expressing his opinion that the derailleur failed subsequent to a
long period of fatigue, and emphasizing his qualifications to make a
judgment on the proximate cause of the derailleur failure by including his
Professional Engineer registration number. He's registered in
The combination of an unbent derailleur hanger on your frame, the lack of a
clearly responsible event like stick in the rear works and the JRA nature
of your ride makes the product suspect for the failure.
Ron's astute input and observation of the structural nature of the failed
RD's upper
It would take about 10,000 lbs to sear that fracture area - you can't do
that on a bike. The failure most likely resulted because of the sharp
corner that could not tolerate just the wrong, but normal, casting
segregation in just the wrong place. It occurred over time until the
reduced
here's a rear view of the Suntour
http://img.photobucket.com/albums/v728/bulldog1935/Raleigh/700c/aP1170010.jpg
here's a rear view of the Shimano 600
http://img.photobucket.com/albums/v728/bulldog1935/Raleigh/F%20Moser/aP5190022.jpg
the corner that started the crack is the upper, just
assume is certainly correct, but you shouldn't claim to speak for others
On Saturday, January 24, 2015 at 2:44:33 PM UTC-6, Steve Palincsar wrote:
On 01/24/2015 09:04 AM, Ron Mc wrote:
I analyze fractures as a professional. The photos clearly show that the
thick part of the fracture and
On 01/24/2015 07:16 PM, John Hawrylak wrote:
I believe the alpha-nurmerics mean Ron is a licensed Professional
Engineer in the state of Texas (TX PE) and his license number is 75665.
Thanks. And thanks, too Ron, for the detailed, clear explanation in
another message regarding the likely
I believe the alpha-nurmerics mean Ron is a licensed Professional Engineer
in the state of Texas (TX PE) and his license number is 75665.
John Hawrylak
Woodstown NJ
On Saturday, January 24, 2015 at 3:44:33 PM UTC-5, Steve Palincsar wrote:
On 01/24/2015 09:04 AM, Ron Mc wrote:
I analyze
On 01/24/2015 09:04 AM, Ron Mc wrote:
I analyze fractures as a professional. The photos clearly show that
the thick part of the fracture and progressively cracked from both
sides before the area was reduced enough to let it pop - it's a
fatigue failure, and it's been going on a long time. TX
I can't copy the image to write on and show you how the fracture
progressed, but it started at that acute corner. I compared the designs of
4 other derailleurs. Campy Chorus, Suntour Cyclone GT, Shimano 600EX and
Shimano Ultegra 6500.
Both the Campy and Suntour have twice the metal at the
I analyze fractures as a professional. The photos clearly show that the
thick part of the fracture and progressively cracked from both sides before
the area was reduced enough to let it pop - it's a fatigue failure, and
it's been going on a long time. TX PE No, 75665
On Friday, January 23,
The 6700 is definitely not new, but you can still get them. The
current is the 6800 and I anticipate that they will be bringing out a
replacement for the 6800 soon since the 105 groupo is now up to pretty
much the same technology standard at 5800. I'm guessing the
replacement will be the 8000
In 35 years of riding I have broken two RD's, but both had lots and lots of
miles on them. Both Campy. One was a NR, which broke much like yours and
the other was a Chorus which broke at the clamp, perhaps from over
tightening. Good news though, if you can trade up the new Ultegra RD 6700
Since I didn't see it happen, I have to do my best to understand based on
the after-effects. I was riding in some sticky mud at the time, but there
was no mud on my chain or on the derailer. I took the photo without
cleaning the RD. It's a bit greasy, but no mud or rocks or sticks were
A completely not-bent derailer tab would definitely suggest that the
derailer just decided to explode itself into bits on its own, which is
indeed WEIRD. JRADSA = Just Riding Along Derailer Self Immolation
On Friday, January 23, 2015 at 1:20:15 PM UTC-8, John wrote:
Since I didn't see it
I'm curious about the CAUSE and the EFFECT. Which was it:
A. Did the derailer just separate into two parts on its own? Then the
broken off part got caught in the spokes, causing you to lurch to a stop?
Cause: Derailer fell apart on its own Effect: Broken bits fell into the
wheel
B.
I wouldn't automatically blame poor metallurgy. There could have been a
precipitating event like a chain jamming that placed a high stress on the
derailleur.
Anton
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There is enough evidence* to suspect Shimano of being overly cheap on its Sora
stuff, and Tiagra is in a similar price range.
*Sora Evidence: I set up three bikes with Sora triples, because I figured, hey
it's just a FD, save some money. All three of mine failed in the exact same
way, and
I had a derailer break in exactly the same place. However, mine was am '88
vintage XT M730
http://velobase.com/ViewComponent.aspx?ID=4a92b92d-00f7-40e0-9694-551ac9e9e554Enum=108
(very solid), and it broke because I picked up one of those little flags
(that mark buried utilities) in the chain and
What JP said...I tend to figure you get what you pay for. Though I figure Grant
and Co did their due diligence on the big wheel Altus rear D. So glad
you came out unscathed.
~Hugh
Los Angeles, CA
On Sunday, January 18, 2015 at 2:56:14 PM UTC-8, John wrote:
Towards the end of my ride today,
I'm glad nothing else was damaged and you weren't roaring downhill in
traffic!
My wife has experience casting non-ferrous metals, and she wasn't surprised
by the apparent variation in density in the photos.
Kind scary...
John
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