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Too-Wide Chain: More Likely To Break?
I just parted the chain on my singlespeed - really standing on it going uphill.
In retrospect, I'm wondering if it's being the widest chain available (operatively, the cheapest....) might have had something to do with the break. I can visualize the cog/chainwheel teeth seating on one side or the other and creating a force that wants to peel the plates off the pins. Replaced it with a properly sized one (3/8?)...but also have a wide chain on my FS/Rohloff bike and am wondering if I should do a premptive replacement. -- PeteCresswell |
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Too-Wide Chain: More Likely To Break?
(Pete Cresswell) wrote:
I just parted the chain on my singlespeed - really standing on it going uphill. In retrospect, I'm wondering if it's being the widest chain available (operatively, the cheapest....) might have had something to do with the break. I can visualize the cog/chainwheel teeth seating on one side or the other and creating a force that wants to peel the plates off the pins. Replaced it with a properly sized one (3/8?)...but also have a wide chain on my FS/Rohloff bike and am wondering if I should do a premptive replacement. This may be completely irrelevant, but Taya's own figures show that their 1/4" chain is a fair bit weaker than their 3/16". |
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Too-Wide Chain: More Likely To Break?
"(Pete Cresswell)" wrote in message . ..
I just parted the chain on my singlespeed - really standing on it going uphill. In retrospect, I'm wondering if it's being the widest chain available (operatively, the cheapest....) might have had something to do with the break. I can visualize the cog/chainwheel teeth seating on one side or the other and creating a force that wants to peel the plates off the pins. Replaced it with a properly sized one (3/8?)...but also have a wide chain on my FS/Rohloff bike and am wondering if I should do a premptive replacement. Dear Pete, While chain sizes are a mystery to me, it sounds as if you put the wrong size nut on a bolt and it stripped. It also sounds as if you've figured it out. That is, if a narrower chain fits your gears "properly," then the wider chain must have been the wrong size. When in doubt, use the right parts. Carl Fogel |
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Too-Wide Chain: More Likely To Break?
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Too-Wide Chain: More Likely To Break?
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#7
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Too-Wide Chain: More Likely To Break?
(Chalo) wrote in message . com...
(Carl Fogel) wrote: Do the gears differ in width? That is, are there thin gears for 3/32 and wide gears for 1/8 chain? Yes. Sprockets for 3/32" chain are about 2mm wide or .080", and those for 1/8" chain are about 3mm wide, or .120" (Even though the chains will accomodate their rated tooth widths of .09375" and .125" respectively) If so, shouldn't a 33% wider 4/32 chain wear or even break differently on a gear intended for 3/32 chain? Maybe in principle it should, but in practice there does not seem to be a problem. Single-speed components have been made in 3/32" tooth widths in order to enable the use of commonly available 3/32" chain as well as the traditional 1/8" kind. While 1/32nd of an inch might be small in terms of lengthwise chain play and tension, it seems rather significant when it's a quarter or a third of the sideways dimension. Why wouldn't it cock a bit sideways, strain, and break as Pete speculated? Because it's still being pulled by teeth whose faces are nominally square to the chainline, engaging rollers that are cylindrical inside and out. If the pull on the chain is in the same plane as both sprockets, then there's no "sideways" about it. The sprocket teeth are significantly narrower than the chain's capacity, even when they are the same nominal size. If they needed to fill the chain's width, they would be wider. Chalo Colina Dear Chalo, Thanks for the detailed numbers. As usual, your patient mechanical explanation makes sense, but that only works with sensible people. I'm stuck on the chain needing to pull in the same plane on both sprockets. While I'm sure that Pete's sprockets are flawlessly in plane, would the kind of bad chain-line sometimes mentioned in this newsgroup be enough to affect matters? That is, if the front sprocket was nicely perpendicular to the frame like the rear axle, but sticking out as far as careless folk sometimes assemble a bicycle, would that small a difference cock the chain sideways enough to lead to trouble? __ _____------------ (I have no idea how far chain-lines get out-of-plane, so I'm being lazy and asking someone with experience. My guess is that your answer will be no, even a typical bad chain-line isn't enough to damage a too-wide chain, but I'd rather know than guess.) Thanks again, Carl Fogel |
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Too-Wide Chain: More Likely To Break?
(Carl Fogel) wrote in message . com...
(Chalo) wrote in message . com... (Carl Fogel) wrote: Do the gears differ in width? That is, are there thin gears for 3/32 and wide gears for 1/8 chain? Yes. Sprockets for 3/32" chain are about 2mm wide or .080", and those for 1/8" chain are about 3mm wide, or .120" (Even though the chains will accomodate their rated tooth widths of .09375" and .125" respectively) If so, shouldn't a 33% wider 4/32 chain wear or even break differently on a gear intended for 3/32 chain? Maybe in principle it should, but in practice there does not seem to be a problem. Single-speed components have been made in 3/32" tooth widths in order to enable the use of commonly available 3/32" chain as well as the traditional 1/8" kind. While 1/32nd of an inch might be small in terms of lengthwise chain play and tension, it seems rather significant when it's a quarter or a third of the sideways dimension. Why wouldn't it cock a bit sideways, strain, and break as Pete speculated? Because it's still being pulled by teeth whose faces are nominally square to the chainline, engaging rollers that are cylindrical inside and out. If the pull on the chain is in the same plane as both sprockets, then there's no "sideways" about it. The sprocket teeth are significantly narrower than the chain's capacity, even when they are the same nominal size. If they needed to fill the chain's width, they would be wider. Chalo Colina Dear Chalo, Thanks for the detailed numbers. As usual, your patient mechanical explanation makes sense, but that only works with sensible people. I'm stuck on the chain needing to pull in the same plane on both sprockets. While I'm sure that Pete's sprockets are flawlessly in plane, would the kind of bad chain-line sometimes mentioned in this newsgroup be enough to affect matters? That is, if the front sprocket was nicely perpendicular to the frame like the rear axle, but sticking out as far as careless folk sometimes assemble a bicycle, would that small a difference cock the chain sideways enough to lead to trouble? __ _____------------ (I have no idea how far chain-lines get out-of-plane, so I'm being lazy and asking someone with experience. My guess is that your answer will be no, even a typical bad chain-line isn't enough to damage a too-wide chain, but I'd rather know than guess.) Thanks again, Carl Fogel People put extreme angles on their chains all the time, with no immediate ill consequence. Picture small ring/small cog or big ring/big cog gear combinations. The derailleur takes care of the chain alignment on the bottom of the cog, but where the chain comes off the top of the cog (where the real stress is) the angle can be quite severe. The OPs chain broke because he used a cheap chain, not because it was too wide. |
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Too-Wide Chain: More Likely To Break?
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#10
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Too-Wide Chain: More Likely To Break?
(Carl Fogel) wrote:
(Chalo) wrote: If the pull on the chain is in the same plane as both sprockets, then there's no "sideways" about it. The sprocket teeth are significantly narrower than the chain's capacity, even when they are the same nominal size. I'm stuck on the chain needing to pull in the same plane on both sprockets. While I'm sure that Pete's sprockets are flawlessly in plane, would the kind of bad chain-line sometimes mentioned in this newsgroup be enough to affect matters? Yes. Chain line is more important on a single-speed drivetrain than on a derailleur drivetrain, because the sprockets are designed to positively retain the chain and their design assumes decent alignment. For small amounts of offset between parallel sprockets, a wider chain is more forgiving simply because it is wider, and thus can run perfectly straight between sprockets that fall to either side of its internal clearance. However, the wider chain has longer pins and wider bushings, and so puts up much more resistance than a narrow to being deflected diagonally. Go-kart enthusiasts (who use chain that is quite wide for its pitch) cope with the occasional terrible sprocket alignment by using so-called "space chain" composed of narrow inner links running on wider outer links, which allows the chain to traverse some lateral distance in a stairstep fashion. When an industrial chain must take up a sizeable offset or angular difference between sprockets, "curved type" chain in used. The bushings in such a chain have a somewhat hourglass-shaped bore and the clearance between inner and outer sideplates is increased to allow the chain to describe a radius as small as 30 times its pitch length. If you look at the pictures under "Chains: Old and New" on Sheldon Brown's informative page http://sheldonbrown.com/chains.html , you can see that the effective bushing area of a modern "bushingless" derailleur-bike chain is even narrower than the narrow chain width would require, and has some of the flaring hourglass-like characteristic that typefies chains intended for misalignment. So today's typical 3/32" chain will tolerate misalignment better than old-style 1/8" chain, but not predominantly because it is narrower. The #40 curved-type chain I have used in machinery is 1/2" pitch like a bike chain, but fully twice as wide. It bends sideways more freely than either kind of bike chain because it is internally configured to do so. Likewise the design characteristics of "bushingless" bike chain allow more sideways flexibility and tolerance of misalignment than a traditional bike chain. In a derailleur bike, poor chainline is a condition of normal operation. But you don't have the choice of running oldfangled 1/8" chain on a derailleur bike, so in that case you're limited to the appropriate kind. (Especially now that traditional 3/32" chain with bushings is on the way to extinction.) Chalo |
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