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Wheel building questions
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On Wed, 13 Oct 2004 10:05:58 +1000, big Pete
wrote: Wrote: On Tue, 12 Oct 2004 23:41:14 +1000, big Pete wrote: David L. Johnson Wrote: You probably have them already, but if not I recommend butted spokes. They make a more reliable wheel. I am a big guy (245 pounds last time I checked) will butted spokes make that big of a strength difference in the wheel? I did not buy the rim and spokes yet. I am thinking of a Sun double walled rim with eyelets that I can get for a good price. And the spokes are 14 gauge stainless steal (non butted) as stated in the my first post. I will Also try to make a dish stick. Looks like I am able to make it from the suggestions you guys have given me. Thank you all Pete Dear Pete, Both thick 14 gauge spokes and thin butted spokes with 14 gauge ends and a 15 gauge middle are more than strong enough to bear the loads--they break at the ends, not in the middle. Double-butted spokes keep the ends thick to try to reduce such breaks. Their advantage is that, being thinner for most of their length, they stretch more and therefore are less likely to lose all tension (a bad thing) as they roll under the hub. When the rim flattens ever so slightly against the pavement, the spoke above it loses tension. A thick straight spoke didn't stretch as far as a thin-center-section spoke, so the thick spoke loses all tension and rattles, going out of true and breaking more often and while the thin spoke can contract that much and still have tension, which makes it likely to last longer. Think of them as rubber bands at the same tension, neither of which is going to snap in the middle, but neither of which we want to go slack. The thinner rubber band enjoys a greater range of motion. Carl Fogel Dear Carl, You are going to have to enlighten me a bit more. I think I agree with your analogy. OK so the thinner band has a better range of motion. But that would imply that they will ware out faster because of the bigger range of motion they are going though. Dear Pete, You raise a good point, but the long thinner middle section of spokes doing the stretching simply doesn't wear out. That is, spokes don't break in the middle. They fatigue, crack, and fail at the elbow about nine times out of ten. The tenth spoke one breaks at the nipple. That's why the spokes are left thick (double-butted) at each end. Even a thin mid-section stainless steel spoke is so strong in tension that it isn't going to fail due to the normal stress cycle of losing and regaining tension as it rolls under the axle. As others have suggested in this thread, this is roughly what Jobst Brandt points out in "The Bicycle Wheel" when he recommends double-butted spokes. Paradoxically, a thinner mid-section spoke produces a more reliable wheel, not because it is stronger than a thicker spoke (it isn't), but because it is more than strong enough and its increased elasticity lets it function better at what spokes need to do, which is to maintain tension throughout the load range without going slack. The metallurgical side of this is that ferrous metals (steels) have the charming characteristic of being able to cycle indefinitely if the stress is low enough--they just won't fatigue and break. (The elbows and nipples break because stress is concentrated there and encouraged by various details like the bending, the threading, and so forth.) So the engineers can design a steel structure to last forever in terms of stress cycles if the stress is kept low enough. Non-ferrous metals like aluminum, titanium, and magnesium do not share this ruggedness. Given enough stress cycles, they fatigue, no matter how low the stress is. The engineers have to design non-ferrous structures to reduce the amount of stress in each cycle, reduce the cycles, or both--and still they can calculate when non-ferrous things should bust. Some theory holds that steels eventually do fatigue even at low stress cycling, but so much later that it's indefinite for practical purposes. But no theory that I know of predicts that a double-butted spoke will wear out in the middle--it will break at the elbow or nipple, but not as soon as a straight, thick spoke that is more prone to losing all tension if it rolls under a heavily loaded axle. For heavier loads, the usual solution is more spokes, not thicker spokes--36 spokes might increase to 48 spokes for many tandems and for truly heavy riders like Chalo Colina, who has about 135 pounds on lightweights like you and 185 pounds on delicate creatures like me. Carl Fogel |
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On Wed, 13 Oct 2004 10:05:58 +1000, big Pete
wrote: Wrote: On Tue, 12 Oct 2004 23:41:14 +1000, big Pete wrote: David L. Johnson Wrote: You probably have them already, but if not I recommend butted spokes. They make a more reliable wheel. I am a big guy (245 pounds last time I checked) will butted spokes make that big of a strength difference in the wheel? I did not buy the rim and spokes yet. I am thinking of a Sun double walled rim with eyelets that I can get for a good price. And the spokes are 14 gauge stainless steal (non butted) as stated in the my first post. I will Also try to make a dish stick. Looks like I am able to make it from the suggestions you guys have given me. Thank you all Pete Dear Pete, Both thick 14 gauge spokes and thin butted spokes with 14 gauge ends and a 15 gauge middle are more than strong enough to bear the loads--they break at the ends, not in the middle. Double-butted spokes keep the ends thick to try to reduce such breaks. Their advantage is that, being thinner for most of their length, they stretch more and therefore are less likely to lose all tension (a bad thing) as they roll under the hub. When the rim flattens ever so slightly against the pavement, the spoke above it loses tension. A thick straight spoke didn't stretch as far as a thin-center-section spoke, so the thick spoke loses all tension and rattles, going out of true and breaking more often and while the thin spoke can contract that much and still have tension, which makes it likely to last longer. Think of them as rubber bands at the same tension, neither of which is going to snap in the middle, but neither of which we want to go slack. The thinner rubber band enjoys a greater range of motion. Carl Fogel Dear Carl, You are going to have to enlighten me a bit more. I think I agree with your analogy. OK so the thinner band has a better range of motion. But that would imply that they will ware out faster because of the bigger range of motion they are going though. Dear Pete, You raise a good point, but the long thinner middle section of spokes doing the stretching simply doesn't wear out. That is, spokes don't break in the middle. They fatigue, crack, and fail at the elbow about nine times out of ten. The tenth spoke one breaks at the nipple. That's why the spokes are left thick (double-butted) at each end. Even a thin mid-section stainless steel spoke is so strong in tension that it isn't going to fail due to the normal stress cycle of losing and regaining tension as it rolls under the axle. As others have suggested in this thread, this is roughly what Jobst Brandt points out in "The Bicycle Wheel" when he recommends double-butted spokes. Paradoxically, a thinner mid-section spoke produces a more reliable wheel, not because it is stronger than a thicker spoke (it isn't), but because it is more than strong enough and its increased elasticity lets it function better at what spokes need to do, which is to maintain tension throughout the load range without going slack. The metallurgical side of this is that ferrous metals (steels) have the charming characteristic of being able to cycle indefinitely if the stress is low enough--they just won't fatigue and break. (The elbows and nipples break because stress is concentrated there and encouraged by various details like the bending, the threading, and so forth.) So the engineers can design a steel structure to last forever in terms of stress cycles if the stress is kept low enough. Non-ferrous metals like aluminum, titanium, and magnesium do not share this ruggedness. Given enough stress cycles, they fatigue, no matter how low the stress is. The engineers have to design non-ferrous structures to reduce the amount of stress in each cycle, reduce the cycles, or both--and still they can calculate when non-ferrous things should bust. Some theory holds that steels eventually do fatigue even at low stress cycling, but so much later that it's indefinite for practical purposes. But no theory that I know of predicts that a double-butted spoke will wear out in the middle--it will break at the elbow or nipple, but not as soon as a straight, thick spoke that is more prone to losing all tension if it rolls under a heavily loaded axle. For heavier loads, the usual solution is more spokes, not thicker spokes--36 spokes might increase to 48 spokes for many tandems and for truly heavy riders like Chalo Colina, who has about 135 pounds on lightweights like you and 185 pounds on delicate creatures like me. Carl Fogel |
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On Wed, 13 Oct 2004 21:12:54 -0700, jim beam
wrote: wrote: On Wed, 13 Oct 2004 10:05:58 +1000, big Pete wrote: Wrote: On Tue, 12 Oct 2004 23:41:14 +1000, big Pete wrote: David L. Johnson Wrote: You probably have them already, but if not I recommend butted spokes. They make a more reliable wheel. I am a big guy (245 pounds last time I checked) will butted spokes make that big of a strength difference in the wheel? I did not buy the rim and spokes yet. I am thinking of a Sun double walled rim with eyelets that I can get for a good price. And the spokes are 14 gauge stainless steal (non butted) as stated in the my first post. I will Also try to make a dish stick. Looks like I am able to make it from the suggestions you guys have given me. Thank you all Pete Dear Pete, Both thick 14 gauge spokes and thin butted spokes with 14 gauge ends and a 15 gauge middle are more than strong enough to bear the loads--they break at the ends, not in the middle. Double-butted spokes keep the ends thick to try to reduce such breaks. Their advantage is that, being thinner for most of their length, they stretch more and therefore are less likely to lose all tension (a bad thing) as they roll under the hub. When the rim flattens ever so slightly against the pavement, the spoke above it loses tension. A thick straight spoke didn't stretch as far as a thin-center-section spoke, so the thick spoke loses all tension and rattles, going out of true and breaking more often and while the thin spoke can contract that much and still have tension, which makes it likely to last longer. Think of them as rubber bands at the same tension, neither of which is going to snap in the middle, but neither of which we want to go slack. The thinner rubber band enjoys a greater range of motion. Carl Fogel Dear Carl, You are going to have to enlighten me a bit more. I think I agree with your analogy. OK so the thinner band has a better range of motion. But that would imply that they will ware out faster because of the bigger range of motion they are going though. Dear Pete, You raise a good point, but the long thinner middle section of spokes doing the stretching simply doesn't wear out. That is, spokes don't break in the middle. They fatigue, crack, and fail at the elbow about nine times out of ten. The tenth spoke one breaks at the nipple. That's why the spokes are left thick (double-butted) at each end. Even a thin mid-section stainless steel spoke is so strong in tension that it isn't going to fail due to the normal stress cycle of losing and regaining tension as it rolls under the axle. As others have suggested in this thread, this is roughly what Jobst Brandt points out in "The Bicycle Wheel" when he recommends double-butted spokes. Paradoxically, a thinner mid-section spoke produces a more reliable wheel, not because it is stronger than a thicker spoke (it isn't), but because it is more than strong enough and its increased elasticity lets it function better at what spokes need to do, which is to maintain tension throughout the load range without going slack. The metallurgical side of this is that ferrous metals (steels) have the charming characteristic of being able to cycle indefinitely if the stress is low enough--they just won't fatigue and break. (The elbows and nipples break because stress is concentrated there and encouraged by various details like the bending, the threading, and so forth.) So the engineers can design a steel structure to last forever in terms of stress cycles if the stress is kept low enough. need more precision here carl. if by "ferrous metals" you mean mild steel, then yes, it has an endurance limit below which it won't fatigue. but if by "ferrous metals" you're including stainless steels, then that's an incorrect statement. endurance limits are a function of carbon content, and carbon is usually kept to a minimum in most stainless steels to prevent harmful formation of chromium carbide. Non-ferrous metals like aluminum, titanium, and magnesium do not share this ruggedness. Given enough stress cycles, they fatigue, no matter how low the stress is. The engineers have to design non-ferrous structures to reduce the amount of stress in each cycle, reduce the cycles, or both--and still they can calculate when non-ferrous things should bust. see above. Some theory holds that steels eventually do fatigue even at low stress cycling, but so much later that it's indefinite for practical purposes. But no theory that I know of predicts that a double-butted spoke will wear out in the middle--it will break at the elbow or nipple, but not as soon as a straight, thick spoke that is more prone to losing all tension if it rolls under a heavily loaded axle. For heavier loads, the usual solution is more spokes, not thicker spokes--36 spokes might increase to 48 spokes for many tandems and for truly heavy riders like Chalo Colina, who has about 135 pounds on lightweights like you and 185 pounds on delicate creatures like me. i'm down to 200, & i'm still riding 16 spoke wheels to no detriment. Carl Fogel Dear Jim and Pete, I expect that Jim's correction about the low-carbon stainless steel used in spokes being more prone to fatigue than other steels is quite right, since materials are Jim's field. But I steel (irresistible) wouldn't worry about the thinner mid-sections of butted spokes wearing out. Again, for Pete's sake (again, irresistible), spokes fatigue and break at the ends, not in the middle. Carl Fogel |
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On Wed, 13 Oct 2004 21:12:54 -0700, jim beam
wrote: wrote: On Wed, 13 Oct 2004 10:05:58 +1000, big Pete wrote: Wrote: On Tue, 12 Oct 2004 23:41:14 +1000, big Pete wrote: David L. Johnson Wrote: You probably have them already, but if not I recommend butted spokes. They make a more reliable wheel. I am a big guy (245 pounds last time I checked) will butted spokes make that big of a strength difference in the wheel? I did not buy the rim and spokes yet. I am thinking of a Sun double walled rim with eyelets that I can get for a good price. And the spokes are 14 gauge stainless steal (non butted) as stated in the my first post. I will Also try to make a dish stick. Looks like I am able to make it from the suggestions you guys have given me. Thank you all Pete Dear Pete, Both thick 14 gauge spokes and thin butted spokes with 14 gauge ends and a 15 gauge middle are more than strong enough to bear the loads--they break at the ends, not in the middle. Double-butted spokes keep the ends thick to try to reduce such breaks. Their advantage is that, being thinner for most of their length, they stretch more and therefore are less likely to lose all tension (a bad thing) as they roll under the hub. When the rim flattens ever so slightly against the pavement, the spoke above it loses tension. A thick straight spoke didn't stretch as far as a thin-center-section spoke, so the thick spoke loses all tension and rattles, going out of true and breaking more often and while the thin spoke can contract that much and still have tension, which makes it likely to last longer. Think of them as rubber bands at the same tension, neither of which is going to snap in the middle, but neither of which we want to go slack. The thinner rubber band enjoys a greater range of motion. Carl Fogel Dear Carl, You are going to have to enlighten me a bit more. I think I agree with your analogy. OK so the thinner band has a better range of motion. But that would imply that they will ware out faster because of the bigger range of motion they are going though. Dear Pete, You raise a good point, but the long thinner middle section of spokes doing the stretching simply doesn't wear out. That is, spokes don't break in the middle. They fatigue, crack, and fail at the elbow about nine times out of ten. The tenth spoke one breaks at the nipple. That's why the spokes are left thick (double-butted) at each end. Even a thin mid-section stainless steel spoke is so strong in tension that it isn't going to fail due to the normal stress cycle of losing and regaining tension as it rolls under the axle. As others have suggested in this thread, this is roughly what Jobst Brandt points out in "The Bicycle Wheel" when he recommends double-butted spokes. Paradoxically, a thinner mid-section spoke produces a more reliable wheel, not because it is stronger than a thicker spoke (it isn't), but because it is more than strong enough and its increased elasticity lets it function better at what spokes need to do, which is to maintain tension throughout the load range without going slack. The metallurgical side of this is that ferrous metals (steels) have the charming characteristic of being able to cycle indefinitely if the stress is low enough--they just won't fatigue and break. (The elbows and nipples break because stress is concentrated there and encouraged by various details like the bending, the threading, and so forth.) So the engineers can design a steel structure to last forever in terms of stress cycles if the stress is kept low enough. need more precision here carl. if by "ferrous metals" you mean mild steel, then yes, it has an endurance limit below which it won't fatigue. but if by "ferrous metals" you're including stainless steels, then that's an incorrect statement. endurance limits are a function of carbon content, and carbon is usually kept to a minimum in most stainless steels to prevent harmful formation of chromium carbide. Non-ferrous metals like aluminum, titanium, and magnesium do not share this ruggedness. Given enough stress cycles, they fatigue, no matter how low the stress is. The engineers have to design non-ferrous structures to reduce the amount of stress in each cycle, reduce the cycles, or both--and still they can calculate when non-ferrous things should bust. see above. Some theory holds that steels eventually do fatigue even at low stress cycling, but so much later that it's indefinite for practical purposes. But no theory that I know of predicts that a double-butted spoke will wear out in the middle--it will break at the elbow or nipple, but not as soon as a straight, thick spoke that is more prone to losing all tension if it rolls under a heavily loaded axle. For heavier loads, the usual solution is more spokes, not thicker spokes--36 spokes might increase to 48 spokes for many tandems and for truly heavy riders like Chalo Colina, who has about 135 pounds on lightweights like you and 185 pounds on delicate creatures like me. i'm down to 200, & i'm still riding 16 spoke wheels to no detriment. Carl Fogel Dear Jim and Pete, I expect that Jim's correction about the low-carbon stainless steel used in spokes being more prone to fatigue than other steels is quite right, since materials are Jim's field. But I steel (irresistible) wouldn't worry about the thinner mid-sections of butted spokes wearing out. Again, for Pete's sake (again, irresistible), spokes fatigue and break at the ends, not in the middle. Carl Fogel |
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jim beam wrote
i'm down to 200, & i'm still riding 16 spoke wheels to no detriment. That depends on what you consider a detriment. Low spoke count wheels are, at best, no stronger than wheels of equal weight with conventional spoke counts. They are also more flexible and a lot more difficult to true and service. They become unrideable from damage that is tolerable to a conventional wheel. --All this in exchange for benefits that lie in the range between unmeasurable and insignificant. Chalo Colina |
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jim beam wrote
i'm down to 200, & i'm still riding 16 spoke wheels to no detriment. That depends on what you consider a detriment. Low spoke count wheels are, at best, no stronger than wheels of equal weight with conventional spoke counts. They are also more flexible and a lot more difficult to true and service. They become unrideable from damage that is tolerable to a conventional wheel. --All this in exchange for benefits that lie in the range between unmeasurable and insignificant. Chalo Colina |
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Chalo wrote:
jim beam wrote i'm down to 200, & i'm still riding 16 spoke wheels to no detriment. That depends on what you consider a detriment. Low spoke count wheels are, at best, no stronger than wheels of equal weight with conventional spoke counts. They are also more flexible and a lot more difficult to true and service. They become unrideable from damage that is tolerable to a conventional wheel. --All this in exchange for benefits that lie in the range between unmeasurable and insignificant. Chalo Colina well, there's one huge advantage of low spoke count wheels - that of wind resistance. let's ignore the arguments about "makes no difference to speed" a moment and look at a much more tangible example. i commute by bike most days by bike across the golden gate bridge to san francisco. it's almost always subject to significant cross wind on both the approaches and on the bridge itself. riding a normal 32 spoke wheelset, my bike is somewhat squirrely when the wind is bad. riding 16 spoke wheels however, the effect of cross winds is substantially less. my low spoke wheels are shimano r540's and they have much deeper rims than my ma3 32 spokers, so if rim alone were the factor, the ma3's would be the less susceptible ride. given the fact that the r540's are better, it can only be that the lower wind resistance /is/ a result of lower spoke count, yes? and i'm not talking a little gust of wind here - i'm talking gnarly stuff that blows the glasses off your face - as has happened. trust me, in those conditions, you want wheels which you /don't/ have to wrestle with the whole way home. |
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