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#1
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RIVENUT and other cracks
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#2
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RIVENUT and other cracks
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... |
#3
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RIVENUT and other cracks
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 |
#4
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RIVENUT and other cracks
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 |
#5
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RIVENUT and other cracks
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. |
#6
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RIVENUT and other cracks
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#7
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RIVENUT and other cracks
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 |
#8
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RIVENUT and other cracks
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. |
#9
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RIVENUT and other cracks
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 |
#10
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RIVENUT and other cracks
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. |
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