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#21
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Bike Weight and Climbing Speed.
On Tue, 05 Jan 2021 10:52:15 -0800, Jeff Liebermann
wrote: On Tue, 05 Jan 2021 01:32:46 -0500, Joy Beeson wrote: On Tue, 05 Jan 2021 08:22:35 +0700, John B. wrote: Thus simply looking at the inside of the tubes with a "bore scope" really is not really a conclusive check as defects can actually be inside the body of the structure. But if a borescope reveals a fatal flaw, there is no need for the more-expensive test. If a flaw is found, and the owner decides to have the CF frame repaired, there's no guarantee that there are no additional defects in the frame. The problem with visual inspection is that it's effectiveness is highly dependent on the abilities of the inspector. In the distant past, I designed marine radios. I could see production defects with little more than a quick glance. Then, a real inspector arrived and showed me what I had missed. With a machine inspection, most of the limitations of the inspector are removed. There is still some interpretation of the results needed, but it's much less than what a visual inspection would require. It's like a doctors diagnosis. Much can be learned by a superficial inspection or probing with a stethoscope. However, if you want detail and a higher confidence level, an X-ray, CT scan, blood test, etc is needed. The problem with any form of testing is that it's really easy to demonstrate that something is unsafe. All it takes is one minor defect or potential problem and the bicycle is instantly declared to be unsafe to ride. However, it's also impossible to demonstrate that something is 100.0% safe to ride. One can run every test and perform every manner of inspection, and still not be certain that bicycle is rideable. Nothing is prefect. In QA (quality assurance), the standard measurement of that uncertainty is the AQL (acceptable quality limit): https://insight-quality.com/what-is-aql-and-what-do-you-need-to-know-about-it/ Basically, it's how many defects a manufacturer is willing to tolerate, how much inspection is necessary to achieve it, and what manner of sample size is necessary to obtain a valid AQL percentage. Ignoring the inevitable debate over what is an acceptable AQL for your bicycle, I should point out that few production bicycles are inspected 100%. Therefore, besides crash damage, the bicycle owner runs the risk of riding a shiny new bicycle with built in defects. Want to lower the risk? Just add $250 to the cost of a new bicycle, buy from a custom frame builder, or do your own $10 inspection. A borescope inspection will probably only catch major defects, but it's better than ignoring the problem or blindly trusting the manufacturer. Pressurizing the frame and looking for air leaks might be amusing. It's not a replacement for a proper ultrasound inspection, but it's a good start. One idea that I posted to RBT in the distant past was to mold conductive wires between the CF layers and measure the resistance (electrical conductivity) between the wires and between the ends of the tubes. If measured and recorded when the frame is new, any changes in resistance will indicate cracking or delamination. For an extreme case, the thin wires should break before the tube collapses. With a sufficient number of wires, the general location of the defect could be found. It wouldn't take much to make a measurement. Some electrical contacts on the surface of the various tubes, a digital ohmmeter (about $50), an a chart of the resisances when the bicycle was new. Carbon fiber conducts electricity. So hook a lead to the top and another to the bottom and measure the resistance? Of course the conduction seems to be in the neighborhood of "2 to 3×105 //basal plane" to quote the reference so that might not work well either :-) https://www.thoughtco.com/table-of-e...ctivity-608499 -- Cheers, John B. |
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#22
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Bike Weight and Climbing Speed.
On Tuesday, January 5, 2021 at 9:04:23 AM UTC-8, wrote:
On Tuesday, January 5, 2021 at 5:28:20 AM UTC-8, AMuzi wrote: On 1/5/2021 12:32 AM, Joy Beeson wrote: On Tue, 05 Jan 2021 08:22:35 +0700, John B. wrote: Thus simply looking at the inside of the tubes with a "bore scope" really is not really a conclusive check as defects can actually be inside the body of the structure. But if a borescope reveals a fatal flaw, there is no need for the more-expensive test. +1 Do you expect Joe Bike Rider to be able to tell a fatal wrinkle flaw simply by it being there as opposed to it being in a critical area which most people wouldn't even be aware of? No, particularly since damage to carbon fiber typically involves sheering between carbon layers or some other invisible disturbance of the Matrix. https://nerdist.com/wp-content/uploa...reeves-759.jpg You need ultrasound or x-ray to see that. There is no spoon. https://www.youtube.com/watch?v=uAXt...l=PabloPARRADO -- Jay Beattie. |
#23
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Bike Weight and Climbing Speed.
On Wed, 06 Jan 2021 06:34:35 +0700, John B.
wrote: Carbon fiber conducts electricity. So hook a lead to the top and another to the bottom and measure the resistance? Of course the conduction seems to be in the neighborhood of "2 to 3×105 //basal plane" to quote the reference so that might not work well either :-) https://www.thoughtco.com/table-of-e...ctivity-608499 Yep. You can buy carbon fiber heaters and carbon fiber floor heating wires with reasonable resistance values. For floor heating wire, about 33 ohms/meter. If anything, the conductivity might be too good and the resulting resistance too low. Some thought to the wire layout might be required. For CF tubing, the resistance depends on the amount of overlap on each sheet. The epoxy is an insulator, which is why I mentioned adding the wire mess between layers. Maybe the wire mesh is not needed and just the resistances across and down the tube is sufficient. I'm fairly sure that just attaching electrodes to the surface of an existing CF bicycle frame is NOT going to work because the clear coating is an insulator[1]. Anyway, think positive. It you don't need am easy way to test for CF frame failure, then just shove some current through the frame and handlebars and you have a way to stay warm on winter rides. As always, more tinkering is necessary: "How to Make a Carbon Fiber Heater" https://www.youtube.com/watch?v=aJBsiWsz8Ck About half way through, he shows how to do it with woven cloth. "DIY Carbon Heated Blanket" https://www.instructables.com/DIY-carbon-heated-blanket/ "Carbon Fiber Insulated Heater Wire" https://www.calcoelectric.com/insulated-heater-wires/carbon-fiber-insulated-heater-wire "12K Heating Carbon Fiber Floor Wire Warm Underfloor Infrared Cable 220V" https://www.ebay.com/itm/100M-12K-Heating-Carbon-Fiber-Floor-Wire-Warm-Underfloor-Infrared-Cable-220V-33-/183895458760 [1] If the frame was built using CF tubing and aluminum lugs, I think that just measuring the resistance between lugs just might work. https://bikerumor-wpengine.netdna-ssl.com/wp-content/uploads/2011/05/swift-exploded-view1.png -- Jeff Liebermann PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
#24
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Bike Weight and Climbing Speed.
On Tue, 05 Jan 2021 16:41:08 -0800, Jeff Liebermann
wrote: On Wed, 06 Jan 2021 06:34:35 +0700, John B. wrote: Carbon fiber conducts electricity. So hook a lead to the top and another to the bottom and measure the resistance? Of course the conduction seems to be in the neighborhood of "2 to 3×105 //basal plane" to quote the reference so that might not work well either :-) https://www.thoughtco.com/table-of-e...ctivity-608499 Yep. You can buy carbon fiber heaters and carbon fiber floor heating wires with reasonable resistance values. For floor heating wire, about 33 ohms/meter. If anything, the conductivity might be too good and the resulting resistance too low. Some thought to the wire layout might be required. For CF tubing, the resistance depends on the amount of overlap on each sheet. The epoxy is an insulator, which is why I mentioned adding the wire mess between layers. Maybe the wire mesh is not needed and just the resistances across and down the tube is sufficient. I'm fairly sure that just attaching electrodes to the surface of an existing CF bicycle frame is NOT going to work because the clear coating is an insulator[1]. Anyway, think positive. It you don't need am easy way to test for CF frame failure, then just shove some current through the frame and handlebars and you have a way to stay warm on winter rides. As always, more tinkering is necessary: "How to Make a Carbon Fiber Heater" https://www.youtube.com/watch?v=aJBsiWsz8Ck About half way through, he shows how to do it with woven cloth. "DIY Carbon Heated Blanket" https://www.instructables.com/DIY-carbon-heated-blanket/ "Carbon Fiber Insulated Heater Wire" https://www.calcoelectric.com/insulated-heater-wires/carbon-fiber-insulated-heater-wire "12K Heating Carbon Fiber Floor Wire Warm Underfloor Infrared Cable 220V" https://www.ebay.com/itm/100M-12K-Heating-Carbon-Fiber-Floor-Wire-Warm-Underfloor-Infrared-Cable-220V-33-/183895458760 [1] If the frame was built using CF tubing and aluminum lugs, I think that just measuring the resistance between lugs just might work. https://bikerumor-wpengine.netdna-ssl.com/wp-content/uploads/2011/05/swift-exploded-view1.png The solution is simple... just don't buy one of those crappy plastic bicycles :-) Added to that most bikes are made in China and as has been decreed that we must not surrender to the Chinese. Make America Great! Don't buy a bicycle. -- Cheers, John B. |
#25
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Bike Weight and Climbing Speed.
On Tuesday, January 5, 2021 at 10:13:09 AM UTC-8, AMuzi wrote:
On 1/5/2021 11:01 AM, Tom Kunich wrote: On Monday, January 4, 2021 at 5:22:42 PM UTC-8, John B. wrote: On Mon, 04 Jan 2021 10:47:14 -0800, Jeff Liebermann wrote: On Mon, 4 Jan 2021 10:07:25 -0800 (PST), Tom Kunich wrote: `Wrinkles may or may not be a problem. The real problems are voids and you have to have a lot of experience with the position and placement of voids to be able to know whether they are a threat or not. Buying the improper tool - a scope instead of an ultrasonic scanner, makes little sense. From 2016: "Why isn’t the bike industry scanning composites for flaws?" https://www.bikebiz.com/why-isnt-the-bike-industry-scanning-composites-for-flaws/ CT scanning is faster while ultrasound is cheaper. Only £400,000 for a CT scanner. No clue on the price of an ultrasound scanner. A $10 borescope or endoscope certainly has its limitations, but methinks sufficient for finding really gross problems. I don't do CF so I don't know what's involved, but the borescope was rather handy for inspecting welds and repairs on steel and aluminum frames. From 2020: "Ruckus Composites Inspects Thousands of Bikes with One Ultrasonic Thickness Gage" https://www.olympus-ims.com/en/insight/ruckus-composites-inspects-thousands-of-bikes-with-one-ultrasonic-thickness-gage/ https://www.olympus-ims.com/en/45mg/ Only $2,400 ea: https://www.ebay.com/itm/Olympus-Panametrics-45MG-Ultrasonic-Thickness-Gage-w-D7906-SM-Transducer-Gauge-/353320469558 Maybe you can take up a collection among the local CF riders and share the expense? One of the problems is that weak points in composite structures are frequently a matter of various layers of the fabric not being completely saturated with the adhesive and thus not adhering to the adjacent layers completely. To completely check the structure you will require something that can check the entire thickness of the structure and check it completely with no spots missed as even a tiny point with lower strength can result in a stress concentration point. Thus simply looking at the inside of the tubes with a "bore scope" really is not really a conclusive check as defects can actually be inside the body of the structure. -- Cheers, John B. Perhaps you should cease showing your vast unknowledge of carbon fiber construction methods? They use "prepreg" which is all uniformly coated with the resin. In theory. But just as aluminum sand castings can have serious structural voids, fiberglas or carbon layups can be done both well and badly. Trek even owns a trademark on the acronym 'OCLV': http://tmsearch.uspto.gov/bin/showfi...805:68wqot.2.1 Which stands for Optimum Compaction Low Void. Hmm. Not zero voids, just fewer or smaller... -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 And I've commented before on Trek's construction techniques. Look is built pretty much like the others but with extremely high standards which means that you have to be careful to only buy a Look from a registered Look Dealer because they are supposed to destroy all of the one's that do not meet their strict standards but instead often they are snuck out of the factory and sold as "barely used". |
#26
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Bike Weight and Climbing Speed.
On Wed, 06 Jan 2021 08:05:41 +0700, John B.
wrote: The solution is simple... just don't buy one of those crappy plastic bicycles :-) Added to that most bikes are made in China and as has been decreed that we must not surrender to the Chinese. Make America Great! Don't buy a bicycle. Sigh. Yet another tech discussion that will soon degenerate into a political discussion. Yes, I know I'm part of the problem but you don't need to follow my bad example. Make RBT great again. Don't mix tech and politics. Also, what do you have against plastic bicycles? https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch Soon everyone will be riding cheap molded plastic bicycles that look something like this: https://bicycledesign.net/2008/07/a-recycled-plastic-bike/ -- Jeff Liebermann PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
#27
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Bike Weight and Climbing Speed.
On Tue, 05 Jan 2021 19:11:30 -0800, Jeff Liebermann
wrote: On Wed, 06 Jan 2021 08:05:41 +0700, John B. wrote: The solution is simple... just don't buy one of those crappy plastic bicycles :-) Added to that most bikes are made in China and as has been decreed that we must not surrender to the Chinese. Make America Great! Don't buy a bicycle. Sigh. Yet another tech discussion that will soon degenerate into a political discussion. Yes, I know I'm part of the problem but you don't need to follow my bad example. Make RBT great again. Don't mix tech and politics. Also, what do you have against plastic bicycles? https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch Soon everyone will be riding cheap molded plastic bicycles that look something like this: https://bicycledesign.net/2008/07/a-recycled-plastic-bike/ I don't have anything against plastic bicycles. I was just using the term "cheap plastic" as seems to be used in America, or at least as used by Google. Try it, google on "cheap plastic", I get 1,240,000,000 "hits" :-) But, being somewhat of a traditionalist I ride steel bikes which have the added benefit of being something that I can repair myself. -- Cheers, John B. |
#28
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Bike Weight and Climbing Speed.
On Wed, 06 Jan 2021 10:35:52 +0700, John B.
wrote: On Tue, 05 Jan 2021 19:11:30 -0800, Jeff Liebermann wrote: On Wed, 06 Jan 2021 08:05:41 +0700, John B. wrote: The solution is simple... just don't buy one of those crappy plastic bicycles :-) Added to that most bikes are made in China and as has been decreed that we must not surrender to the Chinese. Make America Great! Don't buy a bicycle. Sigh. Yet another tech discussion that will soon degenerate into a political discussion. Yes, I know I'm part of the problem but you don't need to follow my bad example. Make RBT great again. Don't mix tech and politics. Also, what do you have against plastic bicycles? https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch Soon everyone will be riding cheap molded plastic bicycles that look something like this: https://bicycledesign.net/2008/07/a-recycled-plastic-bike/ I don't have anything against plastic bicycles. I was just using the term "cheap plastic" as seems to be used in America, or at least as used by Google. Try it, google on "cheap plastic", I get 1,240,000,000 "hits" :-) When wrapped with double quotes, I only get 6,040,000 hits: https://www.google.com/search?q=%22cheap+plastic%22 If I limit the search to only include "cheap plastic" and "bicycle", I get 2,480,000 hits: https://www.google.com/search?q=%22cheap+plastic%22+and+%22bicycle%22 Ok, I give up. In the bicycle world, anything plastic is considered cheap, and anything cheap must be made of plastic. But, being somewhat of a traditionalist I ride steel bikes which have the added benefit of being something that I can repair myself. Same here. My remaining two bicycles are both steel. The Miyata 610 was professionally straightened. My welding abilities were not good enough to insure success. Note the rusted area on the left seat stay: http://www.learnbydestroying.com/jeffl/pics/bicycles/#Miyata-610.JPG I never got around to painting it. My other bicycle, a Gary Fisher Tassajara, doesn't (currently) need any work done on the frame: http://www.learnbydestroying.com/jeffl/pics/bicycles/#Gary-Fisher-Tassajara.JPG -- Jeff Liebermann PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
#29
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Bike Weight and Climbing Speed.
On Tue, 05 Jan 2021 22:28:26 -0800, Jeff Liebermann
wrote: On Wed, 06 Jan 2021 10:35:52 +0700, John B. wrote: On Tue, 05 Jan 2021 19:11:30 -0800, Jeff Liebermann wrote: On Wed, 06 Jan 2021 08:05:41 +0700, John B. wrote: The solution is simple... just don't buy one of those crappy plastic bicycles :-) Added to that most bikes are made in China and as has been decreed that we must not surrender to the Chinese. Make America Great! Don't buy a bicycle. Sigh. Yet another tech discussion that will soon degenerate into a political discussion. Yes, I know I'm part of the problem but you don't need to follow my bad example. Make RBT great again. Don't mix tech and politics. Also, what do you have against plastic bicycles? https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch Soon everyone will be riding cheap molded plastic bicycles that look something like this: https://bicycledesign.net/2008/07/a-recycled-plastic-bike/ I don't have anything against plastic bicycles. I was just using the term "cheap plastic" as seems to be used in America, or at least as used by Google. Try it, google on "cheap plastic", I get 1,240,000,000 "hits" :-) When wrapped with double quotes, I only get 6,040,000 hits: https://www.google.com/search?q=%22cheap+plastic%22 If I limit the search to only include "cheap plastic" and "bicycle", I get 2,480,000 hits: https://www.google.com/search?q=%22cheap+plastic%22+and+%22bicycle%22 Ok, I give up. In the bicycle world, anything plastic is considered cheap, and anything cheap must be made of plastic. But, being somewhat of a traditionalist I ride steel bikes which have the added benefit of being something that I can repair myself. Same here. My remaining two bicycles are both steel. The Miyata 610 was professionally straightened. My welding abilities were not good enough to insure success. Note the rusted area on the left seat stay: http://www.learnbydestroying.com/jeffl/pics/bicycles/#Miyata-610.JPG I never got around to painting it. My other bicycle, a Gary Fisher Tassajara, doesn't (currently) need any work done on the frame: http://www.learnbydestroying.com/jeffl/pics/bicycles/#Gary-Fisher-Tassajara.JPG All my bikes are plain old road bikes, two that I bought second hand at a used bike dealer in Bangkok and then rebuilt and one I built from tubes and lugs largely as I wanted to see how difficult it really was to make a bicycle. -- Cheers, John B. |
#30
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Bike Weight and Climbing Speed.
On 1/5/2021 9:11 PM, Jeff Liebermann wrote:
On Wed, 06 Jan 2021 08:05:41 +0700, John B. wrote: The solution is simple... just don't buy one of those crappy plastic bicycles :-) Added to that most bikes are made in China and as has been decreed that we must not surrender to the Chinese. Make America Great! Don't buy a bicycle. Sigh. Yet another tech discussion that will soon degenerate into a political discussion. Yes, I know I'm part of the problem but you don't need to follow my bad example. Make RBT great again. Don't mix tech and politics. Also, what do you have against plastic bicycles? https://www.google.com/search?q=molded+plastic+concept+bicycle&tbm=isch Soon everyone will be riding cheap molded plastic bicycles that look something like this: https://bicycledesign.net/2008/07/a-recycled-plastic-bike/ meh. It's been done: http://copakeauction.com/ws/wp-conte.../05/101a_1.jpg -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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