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Old 08-22-13, 08:46 PM   #1
hillsbreakme
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Aluminum frame ruined?

Hello people, pardon my stupidity. I did something not too bright, I tried removing a rivet nut from my aluminum frame bike by twisting it out. What I got was a mushroomed hole that I had to gently hammer back into shape, while doing so I apparently created a short crack in the frame next to the hole.

Before I install another rivet nut and take this bike out for some riding, is this bike safe? Can I expect this crack to expand and propagate or am I worried about something that probably won't happen? Picture should be attached. Thank you.

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Old 08-23-13, 01:06 PM   #2
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Yes, you should be worried. Luckily the tube in question is attached at both ends so if the crack were to extend around the tube and fully fail the frame would still stay in the same shape, for a little while, depending on how much stress it was seeing.

I suppose that a repair could be done. Drill the crack's ends and bond on a patch. But good luck finding any one with insurance who would be willing to do this.

You probably know that this is why some of us like steel frames... Andy.
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Old 08-23-13, 07:36 PM   #3
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Thanks for the reply, I think you might have been fooled by the light reflection in the photo? The crack is only about 1/2" long on the south part of the rivet hole, I was worried the crack might start growing bigger if I keep riding the bike.
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Old 08-23-13, 09:05 PM   #4
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I think I see what you are refering to, crack wise. Cracks will tend to follow the paths of stress. The reaming out of the RivNut hole and reforming it back was one type of stress. The riding will have it's stress, different from what has already violated the tube.

I have had one more thought. You could open up the hole until the crack was consumed by the new larger hole. Then monitor the frame for future cracks. Andy.
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Old 08-24-13, 03:11 AM   #5
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A 1/2" crack is pretty big - well, any crack is bad, but that's quite a lot. However it's in a relatively unstressed part of the frame. I'd leave it completely alone and monitor it closely, if you're determined to ride the frame.
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Old 08-24-13, 05:28 AM   #6
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Just take it to a good welding shop and have it welded...Might not look the best but will be safe.
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Old 08-24-13, 08:04 AM   #7
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welding will not save this frame for very long, it's toast. 1/2" is a huge crack. Any crack that is visible by eye is an unsafe crack. This frame would fail within a month, if not on the first ride. And when the dt lets go, so does the tt.
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Old 08-27-13, 09:08 PM   #8
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Drill the end of the crack with a very small diameter drill to stop propagation, but keep an eye on it, since it'll certainly start spreading again (the stop drilling is a temporary fix). Welding is probably the only fix, but it'll anneal the aluminum and leave a weak spot. Hopefully that spot is unstressed enough that it doesn't matter, but I would keep an eye on it anyhow.
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