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Old 01-05-10, 05:52 PM   #1
danjammin
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Cracked lug-tube joint

Been looking at this frame recently and have just noticed a crack approximately 1cm long where the downtube is brazed into the lower headtube lug. It looks rusted in there, so it's probably been there for some time. There are also striations on the lug itself, where the paint seems to have cracked for some reason (maybe impact?).

Does anyone with experience of seeing this type of issue recognise the cause, severity, and possible remedy?
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Old 01-05-10, 08:10 PM   #2
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That looks like a void area where the brazing material didn't completely fill the space under the lug. Chances are it's just a cosmetic issue but if you're thinking of repainting the frame you could fill it with fresh braze before you paint it.
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Old 01-05-10, 10:19 PM   #3
danjammin
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Thanks for that thought, it's probably the least worrisome possibility. The only thing is that a void wouldn't explain the paint markings and the way the lug looks to be bulging a little on top of the tube.
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Old 01-06-10, 11:06 AM   #4
bobbycorno
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The striations are definite signs of a frontal impact, and the void on the lug shoreline looks more like a crack (also impact-related) than a gap to these eyes.

SP
Bend, OR
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Old 01-06-10, 12:36 PM   #5
biaddiction
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Quote:
Originally Posted by danjammin View Post
Been looking at this frame recently and have just noticed a crack approximately 1cm long where the downtube is brazed into the lower headtube lug. It looks rusted in there, so it's probably been there for some time. There are also striations on the lug itself, where the paint seems to have cracked for some reason (maybe impact?).

Does anyone with experience of seeing this type of issue recognise the cause, severity, and possible remedy?
Did you get this frame since it is new? Do you know it's history? My Bianchi also has this kind of paint cracks on this lug and the upper lug as well after my serious frontal crash.
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Old 01-06-10, 03:34 PM   #6
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With all the pictures of cracked Bianchis I've seen, I'd avoid this unless it was really cheap. It probably isn't dangerous as it sits, but it is likely to propagate.
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Old 01-06-10, 04:28 PM   #7
danjammin
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Thanks for the replies, it appeared to me like there was some type of (perhaps very great) impact, due to the cracking and indications in the paint.

As it's not welded, I wouldn't imagine the crack would be able to cross into a tube or the lug, but there seems little to stop it from separating all the way around. The lug itself doesn't seem to be cracked under the paint, with the chrome still intact. However, there does seem to be a smaller crack across the centre of the B, helping to explain the striations emanating from that area on both sides. Hmmm....
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Old 01-07-10, 10:42 PM   #8
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if you look here and elsewhere for cracked Bianchis, you'll find that the ones with this lug style had some problems with fill. They probably had some problems with overheating the thin parts of the lugs near the "B" on Friday after a wine-fueled lunch. The thing about the cracks propagating into the tubes is that you have now produced a couple of new stress risers where the braze failed. Hard to predict if that will happen in this case, but it has happened before.
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