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Impending rim failure (spoke pull-through)??
http://www.flickr.com/photos/p_myron...06432/sizes/l/
You'll see a silver Velocity Aerohead rim. According to the builder, the rim was stress relieved (JB's method) and tensioned to 100 - 110 kgf. On both sides of each spoke hole, the aluminum appears to be under significant stress by the discoloration (lighter color). Capturing this with a photograph was tough as the lighting has to be just right to notice it even with the wheel in front of you. In the photo, you can only see it at the left and middle holes, but this is happening at all 32 holes. Is this normal? Scary? Immediately dangerous? To me, it seems to indicate that there's a bit too much tension in the spokes. But I'm definitely among the uninitiated when it comes to wheel building -- all of my rims up to this point have been anodized black, which might be hiding this from me. FWIW, the wheel has taken a good bit of abuse already and still quite true. Thanks, \\paul -- Paul M. Hobson ..:change the f to ph to reply:. |
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#2
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Impending rim failure (spoke pull-through)??
Paul M. Hobson wrote:
http://www.flickr.com/photos/p_myron...06432/sizes/l/ You'll see a silver Velocity Aerohead rim. According to the builder, the rim was stress relieved (JB's method) and tensioned to 100 - 110 kgf. On both sides of each spoke hole, the aluminum appears to be under significant stress by the discoloration (lighter color). Capturing this with a photograph was tough as the lighting has to be just right to notice it even with the wheel in front of you. In the photo, you can only see it at the left and middle holes, but this is happening at all 32 holes. Is this normal? Scary? Immediately dangerous? To me, it seems to indicate that there's a bit too much tension in the spokes. But I'm definitely among the uninitiated when it comes to wheel building -- all of my rims up to this point have been anodized black, which might be hiding this from me. FWIW, the wheel has taken a good bit of abuse already and still quite true. Thanks, \\paul what you're looking at is deformation caused by the spoke nipple head. spoke nipples vary slightly in profile and size from manufacturer to manufacturer, model to model, and clearly whatever you have isn't an exact match for the rim drilling. that said however, the cracks in the anodizing that you can see [that's what you're looking at] are oriented perpendicular to the rim's traditional axial rim cracking mode and are therefore not a problem. just ride until the braking surfaces wear out. |
#3
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Impending rim failure (spoke pull-through)??
On May 10, 8:39*am, "Paul M. Hobson" wrote:
http://www.flickr.com/photos/p_myron...06432/sizes/l/ You'll see a silver Velocity Aerohead rim. *According to the builder, the rim was stress relieved (JB's method) and tensioned to 100 - 110 kgf. *On both sides of each spoke hole, the aluminum appears to be under significant stress by the discoloration (lighter color). Capturing this with a photograph was tough as the lighting has to be just right to notice it even with the wheel in front of you. *In the photo, you can only see it at the left and middle holes, but this is happening at all 32 holes. Is this normal? *Scary? *Immediately dangerous? *To me, it seems to indicate that there's a bit too much tension in the spokes. *But I'm definitely among the uninitiated when it comes to wheel building -- all of my rims up to this point have been anodized black, *which might be hiding this from me. FWIW, the wheel has taken a good bit of abuse already and still quite true.. Thanks, \\paul -- Paul M. Hobson .:change the f to ph to reply:. Basically, this is normal, you can keep using the wheel. This is a known issue with Velocity Aerohead rims. The valley inside the rim is too narrow for many spoke nipple heads, so the rim bulges and crazes the anodizing. Typically, with use you might eventually get little cracks emanating laterally from the edges of the spoke holes. These cracks seem to relieve the outward stress in the rim and usually grow to about a millimeter or two in length. Eventually they reach a stable length and don't get any bigger, even with more use. Maybe it's the substantial circumferential compressive stress that keeps them from growing... |
#4
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Impending rim failure (spoke pull-through)??
On May 10, 7:39*am, "Paul M. Hobson" wrote:
http://www.flickr.com/photos/p_myron...06432/sizes/l/ You'll see a silver Velocity Aerohead rim. *According to the builder, the rim was stress relieved (JB's method) and tensioned to 100 - 110 kgf. *On both sides of each spoke hole, the aluminum appears to be under significant stress by the discoloration (lighter color). Capturing this with a photograph was tough as the lighting has to be just right to notice it even with the wheel in front of you. *In the photo, you can only see it at the left and middle holes, but this is happening at all 32 holes. Is this normal? *Scary? *Immediately dangerous? *To me, it seems to indicate that there's a bit too much tension in the spokes. *But I'm definitely among the uninitiated when it comes to wheel building -- all of my rims up to this point have been anodized black, *which might be hiding this from me. FWIW, the wheel has taken a good bit of abuse already and still quite true.. Thanks, \\paul -- Paul M. Hobson .:change the f to ph to reply:. Normal, not a problem. |
#5
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Impending rim failure (spoke pull-through)??
On Sat, 10 May 2008 09:39:52 -0400, "Paul M. Hobson"
may have said: http://www.flickr.com/photos/p_myron...06432/sizes/l/ You'll see a silver Velocity Aerohead rim. According to the builder, the rim was stress relieved (JB's method) and tensioned to 100 - 110 kgf. On both sides of each spoke hole, the aluminum appears to be under significant stress by the discoloration (lighter color). Capturing this with a photograph was tough as the lighting has to be just right to notice it even with the wheel in front of you. In the photo, you can only see it at the left and middle holes, but this is happening at all 32 holes. Is this normal? Scary? Immediately dangerous? To me, it seems to indicate that there's a bit too much tension in the spokes. But I'm definitely among the uninitiated when it comes to wheel building -- all of my rims up to this point have been anodized black, which might be hiding this from me. FWIW, the wheel has taken a good bit of abuse already and still quite true. The anodizing on the surface of the aluminum in the area of the spoke has crazed, which is entirely normal. Anodization causes formation of a very brittle layer of material on the surface of the metal, and this shatters if the substrate flexes much. The process of bringing the wheel up to tension will cause that much distortion of the area around the spoke hole, and the result is what you see. Nothing to worry about. -- My email address is antispammed; pull WEEDS if replying via e-mail. Typoes are not a bug, they're a feature. Words processed in a facility that contains nuts. |
#6
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Impending rim failure (spoke pull-through)??
Thanks for the responses everyone. I'm glad to hear that this is normal
and not cause for alarm. To be honest, it's actually pretty surprising to me with my limited knowledge of wheels and aluminum's material properties -- but good new nonetheless! \\paul Werehatrack wrote: On Sat, 10 May 2008 09:39:52 -0400, "Paul M. Hobson" may have said: http://www.flickr.com/photos/p_myron...06432/sizes/l/ You'll see a silver Velocity Aerohead rim. According to the builder, the rim was stress relieved (JB's method) and tensioned to 100 - 110 kgf. On both sides of each spoke hole, the aluminum appears to be under significant stress by the discoloration (lighter color). Capturing this with a photograph was tough as the lighting has to be just right to notice it even with the wheel in front of you. In the photo, you can only see it at the left and middle holes, but this is happening at all 32 holes. Is this normal? Scary? Immediately dangerous? To me, it seems to indicate that there's a bit too much tension in the spokes. But I'm definitely among the uninitiated when it comes to wheel building -- all of my rims up to this point have been anodized black, which might be hiding this from me. FWIW, the wheel has taken a good bit of abuse already and still quite true. The anodizing on the surface of the aluminum in the area of the spoke has crazed, which is entirely normal. Anodization causes formation of a very brittle layer of material on the surface of the metal, and this shatters if the substrate flexes much. The process of bringing the wheel up to tension will cause that much distortion of the area around the spoke hole, and the result is what you see. Nothing to worry about. -- Paul M. Hobson ..:change the f to ph to reply:. |
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