What do use think the thickness of primer, paint, and top clear coat is? From the side the cross section of the tube looks "flat" at the site that was disturbed, and it is easily palpable. Perhaps my fingers exaggerated the amount of material removed.
Thanks for your help.
Gary
"James Thomson" <[email hidden]> wrote in message "]news:[email hidden]...
Quoted message said:
Gary Jacobson said:
Today I noticed that it was more than paint that was removed. There is actually a flat spot, and I suppose that maybe 2 mm has been removed so that means some steel besides the paint was abraded away. If it means anything, there are two colors of steel that I can see.
Most bicycle tubes are thinner than 1mm (typically 0.9 to 0.7mm) in their thickest sections, so if you had lost 2mm of material, your tube would be holed. The two colours you can see are probably grey primer, then steel.
Just took a good look at Bianchi TSX UL that I had been running Michelin 25 tires on which are pretty tall. I rode maybe 200 miles with them.This frame has short chain stays.I went to Michelin 23 tires a while back because I noticed that the paint was being rubbed off from grit that would wedge between the tire and the seat tube.
Today I noticed that it was more than paint that was removed. There is actually a flat spot, and I suppose that maybe 2 mm has been removed so that means some steel besides the paint was abraded away. If it means anything, there are two colors of steel that I can see.
Is this frame doomed to fail? I had plans on selling it, but I wonder if it has any value now. I imagine, given all the importance on BB stiffness, that this area (between front deraillure braze on and BB, on rear of seat tube) is a stress focal point.
"Gary Jacobson" <[email hidden]> wrote in message "]news:[email hidden]...
Quoted message said:
Just took a good look at Bianchi TSX UL that I had been running Michelin
25
Quoted message said:
tires on which are pretty tall. I rode maybe 200 miles with them.This
frame
Quoted message said:
has short chain stays.I went to Michelin 23 tires a while back because I noticed that the paint was being rubbed off from grit that would wedge between the tire and the seat tube.
Today I noticed that it was more than paint that was removed. There is actually a flat spot, and I suppose that maybe 2 mm has been removed so
that
Quoted message said:
means some steel besides the paint was abraded away. If it means anything, there are two colors of steel that I can see.
Is this frame doomed to fail? I had plans on selling it, but I wonder if
it
Quoted message said:
has any value now. I imagine, given all the importance on BB stiffness,
that
Quoted message said:
this area (between front deraillure braze on and BB, on rear of seat tube) is a stress focal point.
Any thoughts?
Are you *sure* the frame wasn't made that way (flat to accommodate tire)?
Bill "once thought newish chainrings were missing teeth" S.
Today I noticed that it was more than paint that was removed. There is actually a flat spot, and I suppose that maybe 2 mm has been removed so that means some steel besides the paint was abraded away. If it means anything, there are two colors of steel that I can see.
Most bicycle tubes are thinner than 1mm (typically 0.9 to 0.7mm) in their thickest sections, so if you had lost 2mm of material, your tube would be holed. The two colours you can see are probably grey primer, then steel.
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Is this frame doomed to fail?
Unlikely, but you should protect the bare metal with paint.
I noticed that the paint was being rubbed off from grit that would wedge between the tire and the seat tube.
Quoted message said:
Today I noticed that it was more than paint that was removed. There is actually a flat spot, and I suppose that maybe 2 mm has been removed so that means some steel besides the paint was abraded away. If it means anything, there are two colors of steel that I can see.
Quoted message said:
Is this frame doomed to fail? I had plans on selling it, but I wonder if it has any value now. I imagine, given all the importance on BB stiffness, that this area (between front deraillure braze on and BB, on rear of seat tube) is a stress focal point.
Do you mean a 2mm long section of paint was removed? Not 2mm deep. That tube is not 2mm thick to begin with.
Seat tubes are under less stress than downtubes, BB shells or chainstays - probably not very much torsion on a seat tube. And people ride frames with tube dings for years. Obviously I haven't seen it, but it may never fail - the most severe damage is likely to the resale value.
What do you think the thickness of primer, paint, and top clear coat is?
I've just measured four steel frames - three painted, one powder coated. The overall diameters varied from 28.8 to 29.0mm on a 28.6mm nominal tube. I don't know what paints Bianchi use.
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From the side the cross section of the tube looks "flat" at the site that was disturbed, and it is easily palpable. Perhaps my fingers exaggerated the amount of material removed.
It's not impossible the tube might have been crushed slightly. A Vernier calliper would tell you quickly how the dimensions of the tube have changed.
Today I noticed that it was more than paint that was removed. There is actually a flat spot, and I suppose that maybe 2 mm has been removed so that means some steel besides the paint was abraded away. If it means anything, there are two colors of steel that I can see.
Is this frame doomed to fail? I had plans on selling it, but I wonder if it has any value now. I imagine, given all the importance on BB stiffness, that this area (between front deraillure braze on and BB, on rear of seat tube) is a stress focal point.
It's doomed, Gary, utterly doomed. the safest thing is to stop riding this instant and send it to me for proper disposal. Oh, I forgot to ask, what size is it? Phil Brown
