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Interesting corrosion failure
http://www.yellowjersey.org/photosfr...t/failspok.jpg
2004 chinese Trek low end hybrid with low miles. Rider (est 120lb) says she took it out for the first time this year and during first ride, spokes failed and wheel rubbed the brake. The front wheel, fork, brake, handlebar are severely corroded, perhaps from being parked in a garage with the front closest to a car's daily salt splashes. 8 spokes missing or broken. Spokes failed in the middle, not the heads. A dozen or so green nipples are covered in white efflorescence near the rim (assume these were at the bottom when parked). The other nipples are dingy nickel. Spokes do not respond to a magnet. Being 'stainless' or 'inox' doesn't mean a steel will not corrode, it just succumbs more slowly. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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#2
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Interesting corrosion failure
On Sunday, May 31, 2020 at 11:15:02 AM UTC-7, AMuzi wrote:
http://www.yellowjersey.org/photosfr...t/failspok.jpg 2004 chinese Trek low end hybrid with low miles. Rider (est 120lb) says she took it out for the first time this year and during first ride, spokes failed and wheel rubbed the brake. The front wheel, fork, brake, handlebar are severely corroded, perhaps from being parked in a garage with the front closest to a car's daily salt splashes. 8 spokes missing or broken. Spokes failed in the middle, not the heads. A dozen or so green nipples are covered in white efflorescence near the rim (assume these were at the bottom when parked). The other nipples are dingy nickel. Spokes do not respond to a magnet. Being 'stainless' or 'inox' doesn't mean a steel will not corrode, it just succumbs more slowly. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 I guess living all of my life in California despite being adjacent to the bay, I've been lucky. I've never seen stainless spokes corrode like that. |
#3
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Interesting corrosion failure
On Sun, 31 May 2020 13:14:54 -0500, AMuzi wrote:
http://www.yellowjersey.org/photosfr...t/failspok.jpg 2004 chinese Trek low end hybrid with low miles. Rider (est 120lb) says she took it out for the first time this year and during first ride, spokes failed and wheel rubbed the brake. The front wheel, fork, brake, handlebar are severely corroded, perhaps from being parked in a garage with the front closest to a car's daily salt splashes. 8 spokes missing or broken. Spokes failed in the middle, not the heads. A dozen or so green nipples are covered in white efflorescence near the rim (assume these were at the bottom when parked). The other nipples are dingy nickel. Spokes do not respond to a magnet. Being 'stainless' or 'inox' doesn't mean a steel will not corrode, it just succumbs more slowly. It is difficult to tell from the photo but it looks almost as though the spokes cracked, part way through, then corroded in the crack and than broke the remaining portion. At least there seem to be small shiny sections, as though freshly broken, and large corroded sections at each break. -- cheers, John B. |
#4
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Interesting corrosion failure
On Sun, 31 May 2020 13:14:54 -0500, AMuzi wrote:
http://www.yellowjersey.org/photosfr...t/failspok.jpg 2004 chinese Trek low end hybrid with low miles. Rider (est 120lb) says she took it out for the first time this year and during first ride, spokes failed and wheel rubbed the brake. The front wheel, fork, brake, handlebar are severely corroded, perhaps from being parked in a garage with the front closest to a car's daily salt splashes. 8 spokes missing or broken. Spokes failed in the middle, not the heads. A dozen or so green nipples are covered in white efflorescence near the rim (assume these were at the bottom when parked). The other nipples are dingy nickel. Spokes do not respond to a magnet. Being 'stainless' or 'inox' doesn't mean a steel will not corrode, it just succumbs more slowly. I know you said that the spoke corroded in the middle, but by any chance were they corroded where the spokes cross over and touch other spokes? One problem with stainless is that it can be both anodic and cathodic to itself: https://yarchive.net/metal/galvanic_corrosion.html ...remember that sometimes the above rules must be bent a little for other reasons, and that corrosion can be far more complex than just galvanic corrosion. Look at the stainless steels for example. Most can be both cathodic and anodic to themselves! Corrosion while immersed in sea water can be quite different than corrosion from exposure to pollutants in the atmosphere. In other words, two pieces of stainless steel will develop a sufficient potential between them to produce galvanic corrosion. In the galvanic table in the above URL, note that chromium-nickel-iron appears twice, once as "active" and again as "passive" with quite a large gap in potential between them. I may have seen this while working on marine radios, but did not bother to investigate. In your photo, the upper spoke did not break perpendicular to the axis of the spoke, but rather broke lengthwise, as I would expect if the spoke were under tension or torsion. However, the perpendicular breaks on the other spokes seem to indicate bending, not tension. My guess(tm) is that the wheel already had some broken spokes before the owner took the bicycle for a ride. The white powder(?) kinda looks like aluminum oxide, which is what I would expect if something made from aluminum were leaned against the spokes in a electrolytic (salt) atmosphere. Possibly contact with another bicycle, aluminum rim, frame, rack, floor pump, aluminum bike stand, aluminum bike rack, etc? I'm doing quite a bit of guessing based on only one photo. If you still have the remaining spokes, try match up pairs of several broken spokes in a photo. I suspect I can extract some more guesswork from how the spokes broke. I'm especially interested if they broke where the spokes crossed over each other. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#5
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Interesting corrosion failure
On 6/1/2020 12:40 AM, Jeff Liebermann wrote:
On Sun, 31 May 2020 13:14:54 -0500, AMuzi wrote: http://www.yellowjersey.org/photosfr...t/failspok.jpg 2004 chinese Trek low end hybrid with low miles. Rider (est 120lb) says she took it out for the first time this year and during first ride, spokes failed and wheel rubbed the brake. The front wheel, fork, brake, handlebar are severely corroded, perhaps from being parked in a garage with the front closest to a car's daily salt splashes. 8 spokes missing or broken. Spokes failed in the middle, not the heads. A dozen or so green nipples are covered in white efflorescence near the rim (assume these were at the bottom when parked). The other nipples are dingy nickel. Spokes do not respond to a magnet. Being 'stainless' or 'inox' doesn't mean a steel will not corrode, it just succumbs more slowly. I know you said that the spoke corroded in the middle, but by any chance were they corroded where the spokes cross over and touch other spokes? One problem with stainless is that it can be both anodic and cathodic to itself: https://yarchive.net/metal/galvanic_corrosion.html ...remember that sometimes the above rules must be bent a little for other reasons, and that corrosion can be far more complex than just galvanic corrosion. Look at the stainless steels for example. Most can be both cathodic and anodic to themselves! Corrosion while immersed in sea water can be quite different than corrosion from exposure to pollutants in the atmosphere. In other words, two pieces of stainless steel will develop a sufficient potential between them to produce galvanic corrosion. In the galvanic table in the above URL, note that chromium-nickel-iron appears twice, once as "active" and again as "passive" with quite a large gap in potential between them. I may have seen this while working on marine radios, but did not bother to investigate. In your photo, the upper spoke did not break perpendicular to the axis of the spoke, but rather broke lengthwise, as I would expect if the spoke were under tension or torsion. However, the perpendicular breaks on the other spokes seem to indicate bending, not tension. My guess(tm) is that the wheel already had some broken spokes before the owner took the bicycle for a ride. The white powder(?) kinda looks like aluminum oxide, which is what I would expect if something made from aluminum were leaned against the spokes in a electrolytic (salt) atmosphere. Possibly contact with another bicycle, aluminum rim, frame, rack, floor pump, aluminum bike stand, aluminum bike rack, etc? I'm doing quite a bit of guessing based on only one photo. If you still have the remaining spokes, try match up pairs of several broken spokes in a photo. I suspect I can extract some more guesswork from how the spokes broke. I'm especially interested if they broke where the spokes crossed over each other. The spokes failed about 1/3 from the rim not at the cross (a known issue but not applicable here). Yes, the aluminum rim and the brass nipples appear to have been galvanically engaged. The shiny spots seem to be from riding with spokes flappng around and striking each other and the fork. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#6
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Interesting corrosion failure
On Mon, 01 Jun 2020 08:06:56 -0500, AMuzi wrote:
The spokes failed about 1/3 from the rim not at the cross (a known issue but not applicable here). Thanks. So much for my self corrosion theory. Yes, the aluminum rim and the brass nipples appear to have been galvanically engaged. With severe corrosion only the front part of the bicycle, your observation that the electrolyte (salt) was delivered in the garage by the nearby parked car is probably correct. I wonder if the metal parts on the car were also corroded? Is the local road salt NaCl (sodium chrolide), or one of the alternatives listed? "CURRENT DEICING PRACTICES AND ALTERNATIVE DEICING MATERIALS" https://www.michigan.gov/documents/ch2-deice_51438_7.pdf We don't have road salt problems on the left coast, so this is all new to me. Was there a bank of batteries charged by solar panels or wind nearby? We have such an arrangment in our ham radio repeater building. Despite adequate ventillation, we still manage to get some metal corrosion in the building: http://802.11junk.com/jeffl/crud/k6bj-batteries-02.jpg Putting a bicycle in the battery room would be a really bad idea. The shiny spots seem to be from riding with spokes flappng around and striking each other and the fork. So much for my aluminum contact corrosion theory. I should have known better since other parts of the bicycle were corroded without contact with aluminum. Yes, stainless steel will corrode: "Metallurgy for Dummies - Corrosion Stainless Steel" https://metallurgyfordummies.com/corrosion-stainless-steel.html More examples: https://www.google.com/search?q=stainless+steel+corrosion&tbm=isch -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
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Interesting corrosion failure
On Monday, June 1, 2020 at 9:30:07 AM UTC-7, AMuzi wrote:
On 6/1/2020 12:40 AM, Jeff Liebermann wrote: On Sun, 31 May 2020 13:14:54 -0500, AMuzi wrote: http://www.yellowjersey.org/photosfr...t/failspok.jpg 2004 chinese Trek low end hybrid with low miles. Rider (est 120lb) says she took it out for the first time this year and during first ride, spokes failed and wheel rubbed the brake. The front wheel, fork, brake, handlebar are severely corroded, perhaps from being parked in a garage with the front closest to a car's daily salt splashes. 8 spokes missing or broken. Spokes failed in the middle, not the heads. A dozen or so green nipples are covered in white efflorescence near the rim (assume these were at the bottom when parked). The other nipples are dingy nickel. Spokes do not respond to a magnet. Being 'stainless' or 'inox' doesn't mean a steel will not corrode, it just succumbs more slowly. I know you said that the spoke corroded in the middle, but by any chance were they corroded where the spokes cross over and touch other spokes? One problem with stainless is that it can be both anodic and cathodic to itself: https://yarchive.net/metal/galvanic_corrosion.html ...remember that sometimes the above rules must be bent a little for other reasons, and that corrosion can be far more complex than just galvanic corrosion. Look at the stainless steels for example. Most can be both cathodic and anodic to themselves! Corrosion while immersed in sea water can be quite different than corrosion from exposure to pollutants in the atmosphere. In other words, two pieces of stainless steel will develop a sufficient potential between them to produce galvanic corrosion. In the galvanic table in the above URL, note that chromium-nickel-iron appears twice, once as "active" and again as "passive" with quite a large gap in potential between them. I may have seen this while working on marine radios, but did not bother to investigate. In your photo, the upper spoke did not break perpendicular to the axis of the spoke, but rather broke lengthwise, as I would expect if the spoke were under tension or torsion. However, the perpendicular breaks on the other spokes seem to indicate bending, not tension. My guess(tm) is that the wheel already had some broken spokes before the owner took the bicycle for a ride. The white powder(?) kinda looks like aluminum oxide, which is what I would expect if something made from aluminum were leaned against the spokes in a electrolytic (salt) atmosphere. Possibly contact with another bicycle, aluminum rim, frame, rack, floor pump, aluminum bike stand, aluminum bike rack, etc? I'm doing quite a bit of guessing based on only one photo. If you still have the remaining spokes, try match up pairs of several broken spokes in a photo. I suspect I can extract some more guesswork from how the spokes broke. I'm especially interested if they broke where the spokes crossed over each other. The spokes failed about 1/3 from the rim not at the cross (a known issue but not applicable here). Yes, the aluminum rim and the brass nipples appear to have been galvanically engaged. The shiny spots seem to be from riding with spokes flappng around and striking each other and the fork. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 Isn't that thed area where the butted spokes narrow? |
#8
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Interesting corrosion failure
On 6/1/2020 12:52 PM, Jeff Liebermann wrote:
On Mon, 01 Jun 2020 08:06:56 -0500, AMuzi wrote: The spokes failed about 1/3 from the rim not at the cross (a known issue but not applicable here). Thanks. So much for my self corrosion theory. Yes, the aluminum rim and the brass nipples appear to have been galvanically engaged. With severe corrosion only the front part of the bicycle, your observation that the electrolyte (salt) was delivered in the garage by the nearby parked car is probably correct. I wonder if the metal parts on the car were also corroded? Is the local road salt NaCl (sodium chrolide), or one of the alternatives listed? "CURRENT DEICING PRACTICES AND ALTERNATIVE DEICING MATERIALS" https://www.michigan.gov/documents/ch2-deice_51438_7.pdf We don't have road salt problems on the left coast, so this is all new to me. Was there a bank of batteries charged by solar panels or wind nearby? We have such an arrangment in our ham radio repeater building. Despite adequate ventillation, we still manage to get some metal corrosion in the building: http://802.11junk.com/jeffl/crud/k6bj-batteries-02.jpg Putting a bicycle in the battery room would be a really bad idea. The shiny spots seem to be from riding with spokes flappng around and striking each other and the fork. So much for my aluminum contact corrosion theory. I should have known better since other parts of the bicycle were corroded without contact with aluminum. Yes, stainless steel will corrode: "Metallurgy for Dummies - Corrosion Stainless Steel" https://metallurgyfordummies.com/corrosion-stainless-steel.html More examples: https://www.google.com/search?q=stainless+steel+corrosion&tbm=isch "I wonder if the metal parts on the car were also corroded?" Is that a joke? We're in Wisconsin. https://duckduckgo.com/?q=wisconsin+...es&ia=ima ges Mostly NaCl but various counties, townships, cities and towns experiment with everything and anything (soy sauce tailings from Kikkoman, cheesemaking and pickle brines and beet juice among the more exotic) -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#10
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Interesting corrosion failure
On Mon, 01 Jun 2020 16:16:59 -0500, AMuzi wrote:
On 6/1/2020 12:52 PM, Jeff Liebermann wrote: "I wonder if the metal parts on the car were also corroded?" Is that a joke? We're in Wisconsin. https://duckduckgo.com/?q=wisconsin+...es&ia=ima ges Sorry. I didn't mean to insult Wisconsin by suggesting that it might be lacking in rust. https://en.wikipedia.org/wiki/Rust_Belt Mostly NaCl but various counties, townships, cities and towns experiment with everything and anything (soy sauce tailings from Kikkoman, cheesemaking and pickle brines and beet juice among the more exotic) Ummm... thanks. To preserve my sanity, please forgive me for not researching the relative merits of these food waste products. All seem to be edible, if that's considered a benefit. They probably reek badly if left on a warm road to rot. Egads. I thought you were joking: "Pouring Cheese on Icy Roads in (Where Else?) Wisconsin" https://www.nytimes.com/2013/12/24/us/wisconsin-finds-another-role-for-cheese-de-icing-roads.html Added to rock salt, it produces a mixture that sticks to roads better, freezes at a lower temperature and saves money. https://en.wikipedia.org/wiki/Freezing-point_depression ...NaCl becomes ineffective and other salts are used, such as calcium chloride, magnesium chloride or a mixture of many. These salts are somewhat aggressive to metals, especially iron, so in airports safer media such as sodium formate, potassium formate, sodium acetate, potassium acetate are used instead. That's better. I'm into better living through chemistry. https://en.wikipedia.org/wiki/Better_Living_Through_Chemistry -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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