RIVENUT and other cracks

https://www.google.com/search?hl=en&...tm%3B476%3B315

us steel folk get the picture where the AL tubing is too thin. Supporting a rivenut's flange opposing a hypothetical expanded and reduced thru grooving...let's et out n measure the surface area atop those grooves...

so an epoxy base then sets rivenut onto the 2 AL surfaces increasing effective surface areas by what ? a factor of 2 ?

clearly yawl driving a square peg into a round hole

now abt this extreme bias against extremely lightweight hitech chem vinyl mountings...

http://pardo.net/bike/pic/fail-001/000.html#Frame finds nothing when searching "rivnut." I think the frame failures are entirely mythical.

- Frank Krygowski

On 9/23/2013 10:19 AM, Frank Krygowski wrote:
http://pardo.net/bike/pic/fail-001/000.html#Frame finds nothing when searching "rivnut." I think the frame failures are entirely mythical.

And that in a world with plenty of not-Rivnut failures:

http://www.yellowjersey.org/photosfr...t/SPLITCD2.JPG

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

On 9/23/2013 8:51 AM, AMuzi wrote:
On 9/23/2013 10:19 AM, Frank Krygowski wrote:
http://pardo.net/bike/pic/fail-001/000.html#Frame finds nothing when
searching "rivnut." I think the frame failures are entirely mythical.

And that in a world with plenty of not-Rivnut failures:

http://www.yellowjersey.org/photosfr...t/SPLITCD2.JPG

LOL, in Frank's world, if a Google search shows no results of something
happening then clearly "that something" has never ever occurred because
as we all know, everyone posts everything that happens to everyone
somewhere online. And of course if only one person posts something, then
he or she is the only person in the world that ever experienced that
thing happening, and one person out of eight billion or so is insignificant.

But actually it's true that all the complaints you find online about
Rivnuts on aluminum frames relate to the Rivnut coming loose and
spinning, not the frame cracking (the cracked frame complaints about
Rivnuts are all on carbon fiber frames). And the reason for this is the
way that the frame manufacturers drill the frame tubes and install the
Rivnuts. They are not put in so tight that forcing a stuck bolt, or
over-tightening, would crack the frame. So you don't see the rivet nuts
(whether the Rivnut brand or other brand) with the notches being used on
bicycles.

What we're actually talking about here is the wisdom of a bicycle owner
attempting to drill properly sized, aligned, and spaced, holes in their
frames and riveting in Rivnuts at home. Besides the obvious warranty
issues, unless you have a proper machine shop and the proper tools and
jigs, no one would think that doing this is a good idea.

is epidemic ?


http://velonews.competitor.com/2013/...rivnuts_302588

On Mon, 23 Sep 2013 05:30:40 -0700 (PDT), datakoll
wrote:

https://www.google.com/search?hl=en&...tm%3B476%3B315

Which picture shows a cracked frame caused by a Rivnut?

This one:
http://www.m-gineering.nl/bidonscheur.jpg
"The rivnut (bottlecage mounting) is being pulled through
the frame. Not very threathening in this stage, unless
the crack starts growing in another direction and then
things will happen fast!"
suggests that it might happen, but hasn't yet. I can't be sure, but
that does not look like a Rivnut. The head it too thick. The clean
threads and color suggest steel, not aluminum. Kinda looks like a
steel insert, on a steel frame, with a bad factory resistance welding
job, but I'm not sure.

Hint: If you're worried about a hole causing a stress riser, drill
the hole on the side of the tube that's in compression. Cracks will
radiate from a hole only when the area around the hole is in tension.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 9/23/2013 10:24 AM, Jeff Liebermann wrote:
On Mon, 23 Sep 2013 05:30:40 -0700 (PDT), datakoll
wrote:

https://www.google.com/search?hl=en&...tm%3B476%3B315

Which picture shows a cracked frame caused by a Rivnut?

This one:
http://www.m-gineering.nl/bidonscheur.jpg
"The rivnut (bottlecage mounting) is being pulled through
the frame. Not very threathening in this stage, unless
the crack starts growing in another direction and then
things will happen fast!"

Okay, so _one_ person out of hundreds of millions of people with Rivnut
equipped AL frames have had a failure (assuming that everyone with a
failure posts it somewhere).

Now show us _one_ person who installed Rivnuts themselves and had the
frame crack at the hole for the Rivnut. If you can't then that proves
that no one ever had a problem (assuming that everyone with a failure
posts it somewhere).

Seriously, this idea that if you can't find a post or photo somewhere
that shows that someone has had a specific problem that that proves the
problem doesn't exist is something so ridiculous that only certain of
our Usenet friends could come up with it. It's analogous to taking your
vehicle into the dealer for a problem and the dealer proclaiming "no one
else has ever reported this problem before." Well you could be like
Honda when I wrote them a letter about a problem with a vehicle and
received a response explaining that they were aware of the problem, that
it resulted from a design error, and that they were not going to fix the
vehicles with the problem (every vehicle of that model produced for that
year); at least they were honest about it, but I've never bought another
Honda vehicle as a result.

On Monday, 23 September 2013 18:24:37 UTC+1, Jeff Liebermann wrote:
On Mon, 23 Sep 2013 05:30:40 -0700 (PDT), datakoll

wrote:



https://www.google.com/search?hl=en&...tm%3B476%3B315



Which picture shows a cracked frame caused by a Rivnut?



This one:

http://www.m-gineering.nl/bidonscheur.jpg

is a welding failure !



"The rivnut (bottlecage mounting) is being pulled through

the frame. Not very threathening in this stage, unless

the crack starts growing in another direction and then

things will happen fast!"

suggests that it might happen, but hasn't yet. I can't be sure, but

that does not look like a Rivnut. The head it too thick. The clean

threads and color suggest steel, not aluminum. Kinda looks like a

steel insert, on a steel frame, with a bad factory resistance welding

job, but I'm not sure.



Hint: If you're worried about a hole causing a stress riser, drill

the hole on the side of the tube that's in compression. Cracks will

radiate from a hole only when the area around the hole is in tension.



--

Jeff Liebermann

150 Felker St #D http://www.LearnByDestroying.com

Santa Cruz CA 95060 http://802.11junk.com

Skype: JeffLiebermann AE6KS 831-336-2558

On Monday, 23 September 2013 19:01:37 UTC+1, thirty-six wrote:
On Monday, 23 September 2013 18:24:37 UTC+1, Jeff Liebermann wrote:



Which picture shows a cracked frame caused by a Rivnut

This one:

http://www.m-gineering.nl/bidonscheur.jpg


is a welding failure !


One could possibly punch out that fitting due to the embrittlement, and the tube would be none the worse for the removal. Could then use a die grinder (with appropriate breathing mask) to cut back the metal to clean material.. Using good welding methods, patch the tube. If the tube collapses or splits with the initial boss removal technique, it was probably garbage before the fitting was inappropriately fixed.