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#31
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Something I've been wondering about.
On 2019-03-19 19:24, John B. Slocomb wrote:
On Tue, 19 Mar 2019 19:45:43 -0500, AMuzi wrote: On 3/19/2019 7:11 PM, John B. Slocomb wrote: On Tue, 19 Mar 2019 13:43:33 -0700, Joerg wrote: On 2019-03-19 05:37, AMuzi wrote: On 3/19/2019 6:32 AM, John B. Slocomb wrote: Last Sunday I was on my usual weekly "long ride" (which was hardly as long as it used to be). And I was sort of looking down and the chain was on the big chain ring and the 5th cassette sprocket (9 speed cassette) and I got to thinking. Note the friction losses for a chain drive are usually considered to be very low, the usual efficiency of a chain drive is usually reckoned to be "up to" 98%. But the instructions for installing a chain drive is always to ensure that the drive and driven sprockets are exactly in line. But the conventional bicycle with it's multiple front and rear sprockets does not have the sprockets aligned except in two instances, assuming the usual chain line dimensions. When on the large front chain ring and (usually) the center cassette sprocket on an uneven numbered cassette, and when on the small front chain ring and a larger cassette sprocket. Perhaps two sprockets larger than center. So, if the usually chain efficiency figures are used the chain is delivering the 98%+ efficiency only twice in a possible 18 speed range. What efficiency is being delivered during the periods when the chain is not perfectly aligned? And should one worry about it? Classic chain is roller chain and yes those run dramatically worse when chainline is askew. But after Sedisport, modern derailleur chain has interrupted sideplates with no full roller so they are quite forgiving of misalignment or, viewed another way, better shifting on derailleur systems. One downside is much faster wear but since they are relatively cheaper to make, we just throw them out sooner. I don't know the numbers for efficiency of derailleur chain at various angles but I think you're right although it may well be a reasonable tradeoff for other features. The Sachs-Sedis chains were the best and longest lasting I ever had on the road bike. The bad news is that I used up my last one in 2018 :-( As for cheaper, I don't think that's true. A good KMC 7-speed costs around $20. The Sachs-Sedis used to retain for $5-6 which would probably be $12-23 in today's Dollars. Lesson learned: If you find good stuff like this buy a larger stash. A much larger one. I'm not sure that a good businessman would considering maintaining a large inventory as being more efficient than the same money invested in a profit making part of his bluishness. I've had long arguments about that with board members, CFO and CEO. The decision about how deeply to go into JIT territory should be left to the people who actually need what's in the shipments. Saving a few thousand Dollars worth in capital gains can easily bumerang into hundreds of thousands lost due to a line stop in production because some materials are missing. We can of course ask Andrew to comment as he seems to have been in business since getting off the Ark. Successfully, one assumes :-) Economics papers are written on the subject which is complex. One balances opportunity cost of inventory=cash, time value (NPV) of inventory=cash, expected inflation vs expected depreciation and then there's always the fact that you can't sell it if you don't have it (or a reliable source, which adds cost & uncertainty) short answer- I don't know and neither does anyone else. I did see in the paper Saturday that Adidas expects $400 million in reduced US revenue for 2019 from ongoing inventory shortages and supply chain disruptions. They employ some expensive and skilled people and yet... Years ago the "JIT" - "Just In Time" supply system was considered an innovation, introduced I believe, by the Japanese. When we were involved in supporting the international oil companies in Indonesia we used an abridged system of that sort in our computerized inventory system. Our system used the time taken to deliver in Indonesia (shipping and customs time) from our Singapore warehouse and added the delivery time, if any, from the source to the warehouse, which varied from an hour or so if sourced in Singapore to a month or more if sourced in the U.S. The system automatically updated the times with each item supplied. It wasn't perfect but it did go a long way to keep the customer(s) satisfied. Until one sunny day a large supplier goes down or the dock workers go on strike. I have numerous horror stories about such stuff. -- Regards, Joerg http://www.analogconsultants.com/ |
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#33
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Something I've been wondering about.
On Wednesday, March 20, 2019 at 1:42:59 PM UTC-7, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote: On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote: On Wed, 20 Mar 2019 07:47:58 +1100, James wrote: On 20/3/19 1:16 am, wrote: On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb wrote: Last Sunday I was on my usual weekly "long ride" (which was hardly as long as it used to be). And I was sort of looking down and the chain was on the big chain ring and the 5th cassette sprocket (9 speed cassette) and I got to thinking. Note the friction losses for a chain drive are usually considered to be very low, the usual efficiency of a chain drive is usually reckoned to be "up to" 98%. But the instructions for installing a chain drive is always to ensure that the drive and driven sprockets are exactly in line. But the conventional bicycle with it's multiple front and rear sprockets does not have the sprockets aligned except in two instances, assuming the usual chain line dimensions. When on the large front chain ring and (usually) the center cassette sprocket on an uneven numbered cassette, and when on the small front chain ring and a larger cassette sprocket. Perhaps two sprockets larger than center. So, if the usually chain efficiency figures are used the chain is delivering the 98%+ efficiency only twice in a possible 18 speed range. What efficiency is being delivered during the periods when the chain is not perfectly aligned? And should one worry about it? -- Cheers, John B. The short answer is no. The long answer is: The efficiency due to misalignment in a derrailleur/freehub system is negligible, here's why: 1. The 98% efficiency you mentioned is in fixed systems with a drive providing constant smooth torque. 2. Once a freehub system is installed (like a single-speed (NOT fixed gear)), the efficiency depends almost entirely on the the bio-mechanical pedaling efficiency. In other words, if you don't apply even power throughout the pedal stroke, the efficiency of the entire system drops off dramatically, at this point, losses due to chain misalignment are barely measurable, let alone being perceptible by the rider. I believe John is focused on the efficiency of the chain drive system alone, not the biomechanical efficiency of the person plus the chain. Certainly I was... After all one's "pedal stroke" while it can be altered by practice, to an extent, is essentially a down and back power stroke for even the best riders and a sort of "built in" part of one's riding. 3. Make matters worse by introducing a spring tension system. Now in addition to the bio mechanical inefficiencies, you're adding the ability of the chain drive to take up slack in the system, which allows _you_ to pedal even more inefficiently. Here's a graphic representation: https://hanswinter.wordpress.com/200...your-spinscan/ I think that, and the rest of your post is complete ********. -- Cheers, John B. Ahh, that may be the common transportation rider pedal stroke but pedaling circles is normal for a high performance rider. Though I can no longer hold it up for long and now reserve it for climbing or sprinting. I always pedal circles because my crank arms describe a circle. If you don't like circles, I recommend: http://tinyurl.com/y2nop9m8 -- Jay Beattie. Jay, you said that you raced professionally in one of these postings. Was that a joke or were you serious? |
#34
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Something I've been wondering about.
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote: On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote: On Wed, 20 Mar 2019 07:47:58 +1100, James wrote: On 20/3/19 1:16 am, wrote: On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb wrote: Last Sunday I was on my usual weekly "long ride" (which was hardly as long as it used to be). And I was sort of looking down and the chain was on the big chain ring and the 5th cassette sprocket (9 speed cassette) and I got to thinking. Note the friction losses for a chain drive are usually considered to be very low, the usual efficiency of a chain drive is usually reckoned to be "up to" 98%. But the instructions for installing a chain drive is always to ensure that the drive and driven sprockets are exactly in line. But the conventional bicycle with it's multiple front and rear sprockets does not have the sprockets aligned except in two instances, assuming the usual chain line dimensions. When on the large front chain ring and (usually) the center cassette sprocket on an uneven numbered cassette, and when on the small front chain ring and a larger cassette sprocket. Perhaps two sprockets larger than center. So, if the usually chain efficiency figures are used the chain is delivering the 98%+ efficiency only twice in a possible 18 speed range. What efficiency is being delivered during the periods when the chain is not perfectly aligned? And should one worry about it? -- Cheers, John B. The short answer is no. The long answer is: The efficiency due to misalignment in a derrailleur/freehub system is negligible, here's why: 1. The 98% efficiency you mentioned is in fixed systems with a drive providing constant smooth torque. 2. Once a freehub system is installed (like a single-speed (NOT fixed gear)), the efficiency depends almost entirely on the the bio-mechanical pedaling efficiency. In other words, if you don't apply even power throughout the pedal stroke, the efficiency of the entire system drops off dramatically, at this point, losses due to chain misalignment are barely measurable, let alone being perceptible by the rider. I believe John is focused on the efficiency of the chain drive system alone, not the biomechanical efficiency of the person plus the chain. Certainly I was... After all one's "pedal stroke" while it can be altered by practice, to an extent, is essentially a down and back power stroke for even the best riders and a sort of "built in" part of one's riding. 3. Make matters worse by introducing a spring tension system. Now in addition to the bio mechanical inefficiencies, you're adding the ability of the chain drive to take up slack in the system, which allows _you_ to pedal even more inefficiently. Here's a graphic representation: https://hanswinter.wordpress.com/200...your-spinscan/ I think that, and the rest of your post is complete ********. Ahh, that may be the common transportation rider pedal stroke but pedaling circles is normal for a high performance rider. Though I can no longer hold it up for long and now reserve it for climbing or sprinting. I always pedal circles because my crank arms describe a circle. If you don't like circles, I recommend: http://tinyurl.com/y2nop9m8 Bad ideas live forever: https://www.youtube.com/watch?v=VAlFpcph1LM -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#35
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Something I've been wondering about.
On 21/3/19 1:03 am, JC wrote:
On Wednesday, March 20, 2019 at 8:42:19 AM UTC-4, duane wrote: On 20/03/2019 8:37 a.m., JC wrote: So, pedal stroke efficiency isn't anything a cyclist should be concerned with....got it. Funny, I've never read or heard any reputable coaching source say that learning to pedal circles isn't beneficial. You still haven't. This is a good article, which denotes the difference between "pulling up" on he up stroke versus un-weighting the leg, and why single legged drills are good for making a smooth pedalling circle: https://sites.google.com/a/mpstraini...alingincircles This is a blog. There is no *evidence*. Then.... https://www.bicycling.com/training/a...ing-mechanics/ "Pedaling in a simple circle is a complex thing, but mastering it can save energy, says Todd Carver, biomechanist at Colorado's Boulder Center for Sports Medicine." Todd Carver says but provides no proof. https://roadcyclinguk.com/how-to/tec...fficiency.html "James Spragg of Spragg Cycle Coaching [points] out that many amateur cyclists pump their legs down, in a style which results in ‘spikes’ in torque, rather than a smooth, consistent application of power. “For most cyclists who haven’t been coached, it’s all start-stop-start-stop, leading to torque spikes,” says Spragg. “Therefore, consistent pedalling means no torque spikes with each pedal revolution as you push down through the pedals.” Again, no evidence is presented. snipped more of the same. The top answer here cites two *studies* where researchers & scientists did actual measurements. https://www.quora.com/Are-clipless-p...more-efficient -- JS |
#36
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Something I've been wondering about.
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#37
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Something I've been wondering about.
On Wednesday, March 20, 2019 at 1:51:54 PM UTC-7, wrote:
On Wednesday, March 20, 2019 at 1:42:59 PM UTC-7, jbeattie wrote: On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote: On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote: On Wed, 20 Mar 2019 07:47:58 +1100, James wrote: On 20/3/19 1:16 am, wrote: On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb wrote: Last Sunday I was on my usual weekly "long ride" (which was hardly as long as it used to be). And I was sort of looking down and the chain was on the big chain ring and the 5th cassette sprocket (9 speed cassette) and I got to thinking. Note the friction losses for a chain drive are usually considered to be very low, the usual efficiency of a chain drive is usually reckoned to be "up to" 98%. But the instructions for installing a chain drive is always to ensure that the drive and driven sprockets are exactly in line. But the conventional bicycle with it's multiple front and rear sprockets does not have the sprockets aligned except in two instances, assuming the usual chain line dimensions. When on the large front chain ring and (usually) the center cassette sprocket on an uneven numbered cassette, and when on the small front chain ring and a larger cassette sprocket. Perhaps two sprockets larger than center. So, if the usually chain efficiency figures are used the chain is delivering the 98%+ efficiency only twice in a possible 18 speed range. What efficiency is being delivered during the periods when the chain is not perfectly aligned? And should one worry about it? -- Cheers, John B. The short answer is no. The long answer is: The efficiency due to misalignment in a derrailleur/freehub system is negligible, here's why: 1. The 98% efficiency you mentioned is in fixed systems with a drive providing constant smooth torque. 2. Once a freehub system is installed (like a single-speed (NOT fixed gear)), the efficiency depends almost entirely on the the bio-mechanical pedaling efficiency. In other words, if you don't apply even power throughout the pedal stroke, the efficiency of the entire system drops off dramatically, at this point, losses due to chain misalignment are barely measurable, let alone being perceptible by the rider. I believe John is focused on the efficiency of the chain drive system alone, not the biomechanical efficiency of the person plus the chain. Certainly I was... After all one's "pedal stroke" while it can be altered by practice, to an extent, is essentially a down and back power stroke for even the best riders and a sort of "built in" part of one's riding. 3. Make matters worse by introducing a spring tension system. Now in addition to the bio mechanical inefficiencies, you're adding the ability of the chain drive to take up slack in the system, which allows _you_ to pedal even more inefficiently. Here's a graphic representation: https://hanswinter.wordpress.com/200...your-spinscan/ I think that, and the rest of your post is complete ********. -- Cheers, John B. Ahh, that may be the common transportation rider pedal stroke but pedaling circles is normal for a high performance rider. Though I can no longer hold it up for long and now reserve it for climbing or sprinting. I always pedal circles because my crank arms describe a circle. If you don't like circles, I recommend: http://tinyurl.com/y2nop9m8 -- Jay Beattie. Jay, you said that you raced professionally in one of these postings. Was that a joke or were you serious? I raced with professionals on occasion, but I was never a professional -- unless my staggering winnings as an amateur elevate me to pro status. I once won a crate of Kettle chips, some water bottles, prime change and some free swag that everybody got. I got some t-shirts that didn't fit. I suppose that's not good enough to be considered a pro. And yes, I know about pedaling technique and am tired of hearing about it since it changes every ten minutes -- along with fit. Pedal circles, scrape dog **** off your sole, pedal up and down, etc., etc. I'm waiting for someone to chime in again about the mystical pedaling technique of Jacques Anquetil. We had that long thread about 15-20 years ago with that guy who was going on about Jacques Anquetil. I think he was trying to sell a book. Apparently there are still some dark mysteries about Jacques' pedaling technique. -- Jay Beattie. |
#38
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Something I've been wondering about.
On Wed, 20 Mar 2019 11:06:04 -0700, Joerg
wrote: On 2019-03-19 19:24, John B. Slocomb wrote: On Tue, 19 Mar 2019 19:45:43 -0500, AMuzi wrote: On 3/19/2019 7:11 PM, John B. Slocomb wrote: On Tue, 19 Mar 2019 13:43:33 -0700, Joerg wrote: On 2019-03-19 05:37, AMuzi wrote: On 3/19/2019 6:32 AM, John B. Slocomb wrote: Last Sunday I was on my usual weekly "long ride" (which was hardly as long as it used to be). And I was sort of looking down and the chain was on the big chain ring and the 5th cassette sprocket (9 speed cassette) and I got to thinking. Note the friction losses for a chain drive are usually considered to be very low, the usual efficiency of a chain drive is usually reckoned to be "up to" 98%. But the instructions for installing a chain drive is always to ensure that the drive and driven sprockets are exactly in line. But the conventional bicycle with it's multiple front and rear sprockets does not have the sprockets aligned except in two instances, assuming the usual chain line dimensions. When on the large front chain ring and (usually) the center cassette sprocket on an uneven numbered cassette, and when on the small front chain ring and a larger cassette sprocket. Perhaps two sprockets larger than center. So, if the usually chain efficiency figures are used the chain is delivering the 98%+ efficiency only twice in a possible 18 speed range. What efficiency is being delivered during the periods when the chain is not perfectly aligned? And should one worry about it? Classic chain is roller chain and yes those run dramatically worse when chainline is askew. But after Sedisport, modern derailleur chain has interrupted sideplates with no full roller so they are quite forgiving of misalignment or, viewed another way, better shifting on derailleur systems. One downside is much faster wear but since they are relatively cheaper to make, we just throw them out sooner. I don't know the numbers for efficiency of derailleur chain at various angles but I think you're right although it may well be a reasonable tradeoff for other features. The Sachs-Sedis chains were the best and longest lasting I ever had on the road bike. The bad news is that I used up my last one in 2018 :-( As for cheaper, I don't think that's true. A good KMC 7-speed costs around $20. The Sachs-Sedis used to retain for $5-6 which would probably be $12-23 in today's Dollars. Lesson learned: If you find good stuff like this buy a larger stash. A much larger one. I'm not sure that a good businessman would considering maintaining a large inventory as being more efficient than the same money invested in a profit making part of his bluishness. I've had long arguments about that with board members, CFO and CEO. The decision about how deeply to go into JIT territory should be left to the people who actually need what's in the shipments. Saving a few thousand Dollars worth in capital gains can easily bumerang into hundreds of thousands lost due to a line stop in production because some materials are missing. I can only comment that WE didn't stock anything for ourselves. Only for companies that we were counteracted to support and we received innumerable compliments for speedy shipping and usually for a lower price than the company we were contracted to could get on their own. We can of course ask Andrew to comment as he seems to have been in business since getting off the Ark. Successfully, one assumes :-) Economics papers are written on the subject which is complex. One balances opportunity cost of inventory=cash, time value (NPV) of inventory=cash, expected inflation vs expected depreciation and then there's always the fact that you can't sell it if you don't have it (or a reliable source, which adds cost & uncertainty) short answer- I don't know and neither does anyone else. I did see in the paper Saturday that Adidas expects $400 million in reduced US revenue for 2019 from ongoing inventory shortages and supply chain disruptions. They employ some expensive and skilled people and yet... Years ago the "JIT" - "Just In Time" supply system was considered an innovation, introduced I believe, by the Japanese. When we were involved in supporting the international oil companies in Indonesia we used an abridged system of that sort in our computerized inventory system. Our system used the time taken to deliver in Indonesia (shipping and customs time) from our Singapore warehouse and added the delivery time, if any, from the source to the warehouse, which varied from an hour or so if sourced in Singapore to a month or more if sourced in the U.S. The system automatically updated the times with each item supplied. It wasn't perfect but it did go a long way to keep the customer(s) satisfied. Until one sunny day a large supplier goes down or the dock workers go on strike. I have numerous horror stories about such stuff. Well, we were shipping through Singapore, as I mentioned. No strikes there as they are illegal and labor unions are a part of the government. Maybe we were better planners than you'all :-) -- Cheers, John B. |
#39
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Something I've been wondering about.
On 21/3/19 9:09 am, jbeattie wrote:
On Wednesday, March 20, 2019 at 1:51:54 PM UTC-7, wrote: Jay, you said that you raced professionally in one of these postings. Was that a joke or were you serious? I raced with professionals on occasion, but I was never a professional -- unless my staggering winnings as an amateur elevate me to pro status. I once won a crate of Kettle chips, some water bottles, prime change and some free swag that everybody got. I got some t-shirts that didn't fit. I suppose that's not good enough to be considered a pro. Same here! And yes, I know about pedaling technique and am tired of hearing about it since it changes every ten minutes -- along with fit. Pedal circles, scrape dog **** off your sole, pedal up and down, etc., etc. I'm waiting for someone to chime in again about the mystical pedaling technique of Jacques Anquetil. We had that long thread about 15-20 years ago with that guy who was going on about Jacques Anquetil. I think he was trying to sell a book. Apparently there are still some dark mysteries about Jacques' pedaling technique. I trained and raced with a fellow who had a very ordinary pedalling style, to the point I've seen his legs stop at the dead spots and cause the freewheel to clunk as his legs start moving again. He won several big races as a masters competitor. -- JS |
#40
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Something I've been wondering about.
On Thu, 21 Mar 2019 09:54:33 +1100, James
wrote: On 21/3/19 9:09 am, jbeattie wrote: On Wednesday, March 20, 2019 at 1:51:54 PM UTC-7, wrote: Jay, you said that you raced professionally in one of these postings. Was that a joke or were you serious? I raced with professionals on occasion, but I was never a professional -- unless my staggering winnings as an amateur elevate me to pro status. I once won a crate of Kettle chips, some water bottles, prime change and some free swag that everybody got. I got some t-shirts that didn't fit. I suppose that's not good enough to be considered a pro. Same here! And yes, I know about pedaling technique and am tired of hearing about it since it changes every ten minutes -- along with fit. Pedal circles, scrape dog **** off your sole, pedal up and down, etc., etc. I'm waiting for someone to chime in again about the mystical pedaling technique of Jacques Anquetil. We had that long thread about 15-20 years ago with that guy who was going on about Jacques Anquetil. I think he was trying to sell a book. Apparently there are still some dark mysteries about Jacques' pedaling technique. I trained and raced with a fellow who had a very ordinary pedalling style, to the point I've seen his legs stop at the dead spots and cause the freewheel to clunk as his legs start moving again. He won several big races as a masters competitor. Quite a while ago, probably during the era when Lance Armstrong was winning, I read a test made by (I think the same lab where Lance was tested) of professional pedaling and it was found that during normal riding the majority of the professionals tested applied the majority of the pedal pressure on the down stroke and diminishing amounts on the "back stroke" ,and normally, very little, if any on the "up stroke". Out of the seat "sprinting" was a bit different with larger amount of force applied on the "up stroke" but only for a limited amount of time. But, of course, this was nearly 20 years ago and perhaps "modern" cyclists do it different now. -- Cheers, John B. |
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