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#1
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Something I've been wondering about.
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. |
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#2
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Something I've been wondering about.
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. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#3
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Something I've been wondering about.
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? 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. 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/ The figure 8 graph is where your power is being applied. The pinched points are the dead spots in your stroke. With concentration, you can achieve a much more linear application, as is shown in the second graph. However, this was on a trainer, indoors. Most riders,even good competitive amateurs, can't achieve pedaling efficiency on the road without good training and coaching. To be more succinct, any losses due to misalignment are not only negligible, but nearly moot until the rider can achieve the most bio mechanically efficient pedal stroke, and even then it won't make a helluva lot of difference. This is why riding a fixed gear bike is more efficient - the lack of the freewheel and tension spring force a more effective pedal stroke - it smooths you out. Once the rider can develop a smooth power curve, a fixed gear becomes eve more efficient. And no, before anyone starts prattling on, we are _NOT_ talking about getting more out of the system than you put in (oh no, he's talking about perpetual motion machines!!!) it's purely a less lossy system. You get more _OF_ what you put in, NOT more _THAN_ you put in. Biomechanical efficiency is the real point here. This is why it's better to be able to shift to an easier gear on the climbs - It keeps the _rider_ in an efficient pedaling zone. The rider biomechanical efficiency is significantly more important than the mechanical losses in the system. I know, I know...there are people in this forum who have a pedal stroke so efficient that the losses from the freehub and sprung chain are irrelevant. Sure. Whatever helps you sleep at night. In reality, the most noticeable effect of misalignment is chain wear. |
#4
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Something I've been wondering about.
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. 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/ The figure 8 graph is where your power is being applied. The pinched points are the dead spots in your stroke. With concentration, you can achieve a much more linear application, as is shown in the second graph. However, this was on a trainer, indoors. Most riders,even good competitive amateurs, can't achieve pedaling efficiency on the road without good training and coaching. To be more succinct, any losses due to misalignment are not only negligible, but nearly moot until the rider can achieve the most bio mechanically efficient pedal stroke, and even then it won't make a helluva lot of difference. This is why riding a fixed gear bike is more efficient - the lack of the freewheel and tension spring force a more effective pedal stroke - it smooths you out. Once the rider can develop a smooth power curve, a fixed gear becomes eve more efficient. And no, before anyone starts prattling on, we are _NOT_ talking about getting more out of the system than you put in (oh no, he's talking about perpetual motion machines!!!) it's purely a less lossy system. You get more _OF_ what you put in, NOT more _THAN_ you put in. Biomechanical efficiency is the real point here. This is why it's better to be able to shift to an easier gear on the climbs - It keeps the _rider_ in an efficient pedaling zone. The rider biomechanical efficiency is significantly more important than the mechanical losses in the system. I know, I know...there are people in this forum who have a pedal stroke so efficient that the losses from the freehub and sprung chain are irrelevant. Sure. Whatever helps you sleep at night. In reality, the most noticeable effect of misalignment is chain wear. |
#5
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Something I've been wondering about.
On Tuesday, March 19, 2019 at 7:16:29 AM UTC-7, JC 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. 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/ The figure 8 graph is where your power is being applied. The pinched points are the dead spots in your stroke. With concentration, you can achieve a much more linear application, as is shown in the second graph. However, this was on a trainer, indoors. Most riders,even good competitive amateurs, can't achieve pedaling efficiency on the road without good training and coaching. To be more succinct, any losses due to misalignment are not only negligible, but nearly moot until the rider can achieve the most bio mechanically efficient pedal stroke, and even then it won't make a helluva lot of difference. This is why riding a fixed gear bike is more efficient - the lack of the freewheel and tension spring force a more effective pedal stroke - it smooths you out. Once the rider can develop a smooth power curve, a fixed gear becomes eve more efficient. And no, before anyone starts prattling on, we are _NOT_ talking about getting more out of the system than you put in (oh no, he's talking about perpetual motion machines!!!) it's purely a less lossy system. You get more _OF_ what you put in, NOT more _THAN_ you put in. Biomechanical efficiency is the real point here. This is why it's better to be able to shift to an easier gear on the climbs - It keeps the _rider_ in an efficient pedaling zone. The rider biomechanical efficiency is significantly more important than the mechanical losses in the system. I know, I know...there are people in this forum who have a pedal stroke so efficient that the losses from the freehub and sprung chain are irrelevant. Sure. Whatever helps you sleep at night. In reality, the most noticeable effect of misalignment is chain wear. Thanks for that information. I work on my pedaling circles but it usually doesn't show much difference until near the end of the season. I don't believe that the pros can go much better than 85%. |
#6
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Something I've been wondering about.
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. -- Regards, Joerg http://www.analogconsultants.com/ |
#8
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Something I've been wondering about.
On 2019-03-19 13:43, 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. I meant $12-14. They cost surprisingly little and that wasn't even an online price but LBS. Lesson learned: If you find good stuff like this buy a larger stash. A much larger one. -- Regards, Joerg http://www.analogconsultants.com/ |
#9
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Something I've been wondering about.
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. KMC Z 72 is $10 at the LBS. Work great for 8 pseed and down. -- sig 56 |
#10
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Something I've been wondering about.
On Tuesday, March 19, 2019 at 4:48:11 PM UTC-4, James wrote:
On 20/3/19 1:16 am, wrote: I believe John is focused on the efficiency of the chain drive system alone, not the biomechanical efficiency of the person plus the chain. He was, and I explained why it was irrelvant - biomechanical efficiency. 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 ********. Anything to add? Any mechanical or bio mechanical counterpoints you wish to address? I think we'd all be interested in reading what exactly it is you disagree with, and why. |
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