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#21
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Let the Laughing Begin
On 06/09/2017 2:59 PM, Jeff Liebermann wrote:
On Wed, 6 Sep 2017 11:02:12 -0700 (PDT), Doug Landau wrote: Quantity is my substitute for quality. So, to know the exact pressure at which his tires are inflated, Tom should own a dozen guages, apply them all, and average the results? Sure. The errors tend to random, some high, some low, some large, some small, etc. When a large number of measurements are averaged, the result tends to be fairly close to reality. At least that's what some climate researchers claimed when they averaged the results of many prehistoric temperature and CO2 proxies, each of which were suspected of being inaccurate, and produced an average which the was declared accurate. Actually, it would be more interesting if we took pressure readings at various times of the day. If you set your tire pressure to some number on a cold morning, and then go for a ride in the hot sun, your tire pressure will increase. Strictly speaking, one needs to be seated on the bicycle in order to get an accurate measurement or proper setting. That might be a bit awkward unless you're a contortionist. It might be instructive (and amusing) to attach a BlueGoof wireless tire pressure gauge and data logger to a wheel and watch the variations in pressure as the bicycle bounces down the road or does aerobatics. I suspect that you'll find large variations, which should make you wonder why anyone bothers to set the tire pressure more accurately than hard, firm, mush, soft, and flat. Math, numbers, formulas, and calculations: http://www.velonews.com/2017/03/bikes-and-tech/technical-faq-science-tire-pressure-rim-width-heat-buildup_433214 Math hates me. Or just buy a decent pump and forget about it. |
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#22
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Let the Laughing Begin
On Wednesday, September 6, 2017 at 12:07:47 PM UTC-7, Duane wrote:
On 06/09/2017 2:59 PM, Jeff Liebermann wrote: On Wed, 6 Sep 2017 11:02:12 -0700 (PDT), Doug Landau wrote: Quantity is my substitute for quality. So, to know the exact pressure at which his tires are inflated, Tom should own a dozen guages, apply them all, and average the results? Sure. The errors tend to random, some high, some low, some large, some small, etc. When a large number of measurements are averaged, the result tends to be fairly close to reality. At least that's what some climate researchers claimed when they averaged the results of many prehistoric temperature and CO2 proxies, each of which were suspected of being inaccurate, and produced an average which the was declared accurate. Actually, it would be more interesting if we took pressure readings at various times of the day. If you set your tire pressure to some number on a cold morning, and then go for a ride in the hot sun, your tire pressure will increase. Strictly speaking, one needs to be seated on the bicycle in order to get an accurate measurement or proper setting. That might be a bit awkward unless you're a contortionist. It might be instructive (and amusing) to attach a BlueGoof wireless tire pressure gauge and data logger to a wheel and watch the variations in pressure as the bicycle bounces down the road or does aerobatics. I suspect that you'll find large variations, which should make you wonder why anyone bothers to set the tire pressure more accurately than hard, firm, mush, soft, and flat. Math, numbers, formulas, and calculations: http://www.velonews.com/2017/03/bikes-and-tech/technical-faq-science-tire-pressure-rim-width-heat-buildup_433214 Math hates me. Or just buy a decent pump and forget about it. Better yet just use any floor pump with a guage and forget about it. |
#23
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Let the Laughing Begin
On Wednesday, September 6, 2017 at 2:02:15 PM UTC-4, Doug Landau wrote:
Quantity is my substitute for quality. So, to know the exact pressure at which his tires are inflated, Tom should own a dozen guages, apply them all, and average the results? Yes, of course. But keep in mind that each time a gauge is used, it causes a tiny bit of air to escape, which results in a tiny pressure loss. So rather than a simple average, it would be wise to plot the results in order, then do a best-fit computation to help account for that gradual pressure loss. If you want to be accurate, that is. ;-) - Frank Krygowski |
#24
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Let the Laughing Begin
On Wednesday, September 6, 2017 at 2:59:25 PM UTC-4, Jeff Liebermann wrote:
If you set your tire pressure to some number on a cold morning, and then go for a ride in the hot sun, your tire pressure will increase. As mentioned in the past, I blew out a new and expensive tubular by leaving the bike parked in the hot southern sun. There was a huge bang, and I found a big hole in the center of the tread right at the top. Shoulda used fenders, I guess. - Frank Krygowski |
#25
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Let the Laughing Begin
On Wednesday, September 6, 2017 at 12:07:47 PM UTC-7, Duane wrote:
Or just buy a decent pump and forget about it. As Jeff asked - what is a "decent pump"? A pump that works good on a high pressure racing bike takes forever to inflate an MTB tire. With almost all of the pumps these days using that awful filler valve https://tinyurl.com/y84dcpqn simply isn't right for other applications. |
#26
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Let the Laughing Begin
Doug Landau wrote:
On Wednesday, September 6, 2017 at 12:07:47 PM UTC-7, Duane wrote: On 06/09/2017 2:59 PM, Jeff Liebermann wrote: On Wed, 6 Sep 2017 11:02:12 -0700 (PDT), Doug Landau wrote: Quantity is my substitute for quality. So, to know the exact pressure at which his tires are inflated, Tom should own a dozen guages, apply them all, and average the results? Sure. The errors tend to random, some high, some low, some large, some small, etc. When a large number of measurements are averaged, the result tends to be fairly close to reality. At least that's what some climate researchers claimed when they averaged the results of many prehistoric temperature and CO2 proxies, each of which were suspected of being inaccurate, and produced an average which the was declared accurate. Actually, it would be more interesting if we took pressure readings at various times of the day. If you set your tire pressure to some number on a cold morning, and then go for a ride in the hot sun, your tire pressure will increase. Strictly speaking, one needs to be seated on the bicycle in order to get an accurate measurement or proper setting. That might be a bit awkward unless you're a contortionist. It might be instructive (and amusing) to attach a BlueGoof wireless tire pressure gauge and data logger to a wheel and watch the variations in pressure as the bicycle bounces down the road or does aerobatics. I suspect that you'll find large variations, which should make you wonder why anyone bothers to set the tire pressure more accurately than hard, firm, mush, soft, and flat. Math, numbers, formulas, and calculations: http://www.velonews.com/2017/03/bikes-and-tech/technical-faq-science-tire-pressure-rim-width-heat-buildup_433214 Math hates me. Or just buy a decent pump and forget about it. Better yet just use any floor pump with a guage and forget about it. That's my plan. So far so good. -- duane |
#27
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Let the Laughing Begin
On Wed, 06 Sep 2017 08:54:53 -0700, Jeff Liebermann
wrote: On Wed, 06 Sep 2017 13:30:25 +0700, John B. wrote: On Tue, 05 Sep 2017 09:52:07 -0700, Jeff Liebermann wrote: At one time, I proposed a portable bicycle tire inflator consisting of something like the automotive automatic shutoff compressor that I'm using, with an added LiIon rechargeable battery. Or maybe powered instead by a model airplane gasoline engine. I think I can make it small enough to be fairly flat and pocket size. A little marketing research indicated that nobody I asked would pay money for such a thing but might consider building one from a kit. Very strange but I decided that it was too risky and let the idea die a natural death. I've always believed that a "good pump" was one with which one could inflate the desired tire to the desired pressure :-) Sigh. Inflate the desired tire at what temperature, with how much effort, how quickly, to what accuracy, how big a tire, etc? What works well for a road bicycle, might not be so good inflating an automobile tire. What works in the shop, may not be so good during a ride. Of course, there are specialized bicycle pumps optimized for these and other purposes and conditions. My idea of a "good pump" is one that will do an adequate job of inflating everything from a high pressure racing tire (multistage pump), to an air mattress (large volume piston or vane pump). It might look a bit weird, have capabilities I might rarely use, probably expensive, but will work for anything that needs inflation. You missed the "desired tire to the desired pressure" ;-? Here's one application for an air pump with which I'm currently working: https://www.amazon.com/Carburetor-detector-Replaces-Tillotson-243-504/dp/B06Y542R9S Yes, it's an air pump. It's used to apply pressure to the carburetor fuel inlet on a 2 stroke engine (chain saw) to determine if the needle valve is working properly and not leaking. Apply pressure and it should open the needle valve at about 15 psi. Let it bleed down, and it should close again at 5 psi. Pressurized to 10 psi and dunk the carburetor into a bowl of water while looking for leaks (air bubbles). A "good pump" should be able to do this as well. Yup, we used to do that. Blow into the fuel line. While nobody's cheeks were calibrated in psi it did tell you if the needle valve was leaking. One did have to spit a bit to get the gasoline taste out of your mouth though. :-) The problem here is that this is what I want, not what the GUM (great unwashed masses) are will to buy. That makes it a "good pump" but only for me. You may have other ideas. -- Cheers, John B. |
#29
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Let the Laughing Begin
On Wed, 6 Sep 2017 17:29:34 -0700 (PDT), Doug Landau
wrote: On Tuesday, September 5, 2017 at 11:26:55 PM UTC-7, John B. wrote: On Tue, 5 Sep 2017 07:04:41 -0700 (PDT), wrote: On Monday, September 4, 2017 at 7:32:25 PM UTC-7, John B. wrote: On Mon, 4 Sep 2017 13:00:34 -0700 (PDT), wrote: Yesterday I went on a long enough ride and the weather report turned out to be incorrect enough that I was close to heat prostration near the end. I hit a stone in the road that was invisible and it gave me a flat. As I was trying to figure out how to make the particular CO2 filler in that seat pack to work I punctured the canister and lost one of my two CO2 tubes. Opening the front tire to remove the inner tube and replace it with the new tube a black guy who looked nearly homeless came by and said that he had a patch kit if I needed it. I thanked him but without a pump I couldn't find any leaks to patch. When the front tube came out it was a Performance butyl tube. They were available in a 30, a 40 and a 60 mm stem length. I have bought the latex tubes because they were available in 51 mm stems. The back (which was losing air about the same as the front) is latex. So my tires not losing air plainly isn't because of the material of the tubes. My suspicion is the pump meter. I bought a new Silca professional pump from Andrew and it has a new (and probably much better) pressure gauge on it. This allows me to fill the tire up properly and to test the pressure more accurately than most pumps. So it probably is pump and not inner tube material related. Now don't say I lacked the courage to publicly correct myself when I think I was wrong. How many of you can say the same thing - John and Frank? Actually I don't remember ever saying that you failed to correct yourself. If memory serves what I've said was that "you are wrong". And as usual you didn't know what you were talking about. As someone wrote, "Reality is anything you want it to be. Just close your eyes and let your imagination run wild." -- Cheers, John B. LOL Pat Tillman! :-) But even a casual reading of the "social networks" seems to prove my point :-) -- Cheers, John B. |
#30
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Let the Laughing Begin
As someone wrote, "Reality is anything you want it to be. Just close your eyes and let your imagination run wild." -- Cheers, John B. LOL Pat Tillman! :-) But even a casual reading of the "social networks" seems to prove my point :-) Actually I was reacting to what I wanted to react to not exactly what you said. What trips me out is when people say you make your own reality. Certainly it is a lovely thought and a lovely thing to say to someone seeking inspiration, and certainly the Olympic gold medalist subscribes to the theory. But where does that leave the silver medalist? Who believed and believed and believed and busted and busted and busted their ass? Derek Porter was my first rowing hero. He was in an 8 that got a gold in 92, and was world champ in 93, IIRC, and thot 96 was his year. Look at him try to hold back the tears on the podium in 96* and again in 00. https://www.youtube.com/watch?v=wViOIIh7pUU https://www.google.com/search?q=Dere... cw4dTFyxb5M: *It is well worth watching the whole race, for other reasons. Cheers |
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