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#341
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Spoke tension meter-John Allen responds
Dave vt? writes:
I think both of the JB's are actually in agreement in this matter. One JB calls it residual stress that is relieved, the other calls it bedding in. I don't believe so. Bedding in implies plastic deformation of the hub, not of the spoke. Furthermore, I think you'll find "jim beam" will claim that residual stress caused by spoke manufacture can't be relieved by spoke squeezing. You say: "Bedding in implies plastic deformation of the hub, not of the spoke." I think bedding in implies plastic deformation of the spoke/hub interface. Both the hub and the spoke can give a little in that relationship. "Bedding in" requires yielding. The spoke cross section will not yield from bearing against aluminum. You can bend the wire but that is not "bedding in", that's bending and forming line of the wire, also known for producing residual stress. Bedding is in this context has been used solely to describe the plastic deformation of the flange where the spoke bears on aluminum. Hence the term does not apply in the sense that you seem to propose. |
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#342
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Spoke tension meter-John Allen responds
Joe Riel writes:
I need a value for the radial stiffness of a wheel. Previously I extracted values from the finite element data in "The Bicycle Wheel". Alas, no mention is given of the spoke diameter used in the simulation. In the "Torsional Stiffness of Spoking" table, a diameter of 1.6mm is used. Maybe that is the value used for the simulation. Does a later edition have more information? No, and it wasn't intended to do other than to show typical wheel response to loads. However, radial stiffness is directly related to the compression (in stress analysis terms) of the four or so spokes that change length under load. You can come up with that for typical spokes of your choice. As you see, the number of spokes makes a difference as well. |
#343
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Spoke tension meter-John Allen responds
On Tue, 28 Jun 2005 00:59:19 GMT, Joe Riel
wrote: Carl, Jobst, or anyone, I need a value for the radial stiffness of a wheel. Previously I extracted values from the finite element data in "The Bicycle Wheel". Alas, no mention is given of the spoke diameter used in the simulation. In the "Torsional Stiffness of Spoking" table, a diameter of 1.6mm is used. Maybe that is the value used for the simulation. Does a later edition have more information? Joe Dear Joe, Here's an online FEA of a bicycle wheel similar to Jobst's: http://www.astounding.org.uk/ian/wheel/index.html It uses a spoke diameter of 2 mm. There's a link to the Perl script that creates the model. There's also a link to how it can be used to examine loads in the rim. And there's a link to some comparisons with analyses by Professor Gavin and Andrew Hartz, showing that one used 1.83 mm spokes and the other seemed implausible, giving only an area. The link to the comparisons mentions a few other analyses of bicycle wheels, too. Carl Fogel |
#344
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Spoke tension meter-John Allen responds
Joe Riel wrote:
Carl, Jobst, or anyone, I need a value for the radial stiffness of a wheel. Previously I extracted values from the finite element data in "The Bicycle Wheel". Alas, no mention is given of the spoke diameter used in the simulation. In the "Torsional Stiffness of Spoking" table, a diameter of 1.6mm is used. Maybe that is the value used for the simulation. Does a later edition have more information? Joe How about Francois Grignon's data? http://www.sheldonbrown.com/rinard/wheel/grignon.htm Details are at the link above, but here are the radial stiffnesses: Wheel Radial stiffness(lb/in) Shamal 12 HPW 12 600 Zipp 540 20 200 Mavic Cosmic Expert 13 500 Cane Creek Crono 8800 Specialized tri-spoke 8400 Campagnolo 32 spokes 13 500 Mavic 36 spokes 20 200 |
#345
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Spoke tension meter-John Allen responds
On Thu, 16 Jun 2005 15:27:32 -0700, "Jay Beattie"
wrote: Boston snob! Get the giant Wurlitzer with the monkey stop -- you know, where the little monky bangs the cymbals. That's a crowd pleaser and a must-have for any bicycle shop. You can even get the optional tire inflater stop. -- E. Power Beattie. The organ in a local church here has a stop (among a few dozen) that makes the Star Of Bethlehem turn circles, normally used only on Christmases. Jasper |
#346
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Spoke tension meter-John Allen responds
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