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seat tube deformation

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Old 09-07-21, 09:13 AM
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cyrano138
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seat tube deformation

The seat tube on the bike I'm working on has a very slight bulge where I jammed a screwdriver down in there to pull away the seat post. Just wanted ask what you guys thought about potential safety implications.
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Old 09-07-21, 09:31 AM
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Since you know it's not perfect, the only implication to safety will be if you don't look at it every so often to see if it's becoming a problem.

Being a steel tube, I wouldn't worry too much about it if at all. But I would look at it every now and then.
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Old 09-07-21, 09:37 AM
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You are forbidden from working on bikes
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Old 09-07-21, 10:42 AM
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Originally Posted by Iride01
Since you know it's not perfect, the only implication to safety will be if you don't look at it every so often to see if it's becoming a problem.

Being a steel tube, I wouldn't worry too much about it if at all. But I would look at it every now and then.
Thank you! I will keep a very close eye on it. I was reading in Sheldon's seat post section that you can sometimes see if an oversized post has been forced in by feeling a bulge in the seat tube. He didn't imply that seat tubes in that condition were unusable so I'm hoping for the best.

Originally Posted by trailangel
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Honestly that's fair. Not my proudest moment, but frustration got the better of me.
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Old 09-07-21, 10:57 AM
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I might speculate that maybe tubes also get bulged by seat posts that are slightly too small a diameter for the seat tube and they rock back and forth in the clamp constantly hammering on the inside of the tube. The shorter the seat post remaining in the tube the more force to bend the tube with.

I still can't imagine how you got a screwdriver that far down between the tube and post. Or was the post completely below the top of the tube?
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Old 09-07-21, 11:12 AM
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Originally Posted by Iride01
I might speculate that maybe tubes also get bulged by seat posts that are slightly too small a diameter for the seat tube and they rock back and forth in the clamp constantly hammering on the inside of the tube. The shorter the seat post remaining in the tube the more force to bend the tube with.

I still can't imagine how you got a screwdriver that far down between the tube and post. Or was the post completely below the top of the tube?
I cut almost all the way through the seat post in a couple places with a jab saw. I was trying to push one section in to make room, but I wasn't as far through the seat post on the bottom as I thought.
I posted this in another thread but here's a picture of the seat post.


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Old 09-07-21, 11:37 AM
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Zero safety implications. And figure if you hadn't gotten the post out the frame was garbage anyways.

If it bothers you it might be possible to get the defect out with some blocks as is often done with larger dents. If it were me, though, I would be happy the post was out and ride it without worry.
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Old 09-07-21, 09:57 PM
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Originally Posted by ClydeClydeson
Zero safety implications. And figure if you hadn't gotten the post out the frame was garbage anyways.

If it bothers you it might be possible to get the defect out with some blocks as is often done with larger dents. If it were me, though, I would be happy the post was out and ride it without worry.
Sweet, thank you! The frame had been abused a bit anyway so I wasn't being too careful.
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