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How to repair slightly bent steerer tube.

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How to repair slightly bent steerer tube.

Old 06-19-13, 11:03 PM
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How to repair slightly bent steerer tube.

The somewhat rough 1983 Stumpjumper Sport I recently acquired has a slightly bent steerer tube. This is not a surprise. The seller showed it to me. There is just enough bend to cause it to start to bind at about 70 degrees off center each way, which is far sharper a turn then I would ever make riding.

I'm not worried about going with it as is, but wondered if there is a reasonably easy way to straighten it. You can see that the bend is about 1/3 of the way up the tube and not between the tube and the crown.

Thanks all,

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Old 06-19-13, 11:19 PM
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Originally Posted by RFC View Post
...You can see that the bend is about 1/3 of the way up the tube and not between the tube and the crown.
Thanks all, RFC
Sounds like you might have intended to includa a photo?

Also sounds like a job for a framebuilder, and at least the fork is a lot easier to deliver than a frame. Sounds like a ten-minute repair if the bend is minor.
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Old 06-19-13, 11:33 PM
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Cost me $20 and a trip to the lbs.
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Old 06-20-13, 03:07 AM
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Steerer tubes are thin at the top and butted to a thicker wall at the bottom. Yours bent at the transition more than likely. It would be better to replace it as bending twice in the same place won't reverse the first bend, it just stretches the material further causing more damage.
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Old 06-20-13, 06:24 AM
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Straightening a bent steerer is almost impossible to do accurately. Often it will appear straight but in fact is just straighter. While it will probably work without binding, it will likely result in abnormal and premature wear of the headset races. Properly straightening a steering would be such a time consuming process (unless you got lucky) that it would probably be cheaper to have the steerer replaced.
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Old 06-20-13, 07:30 AM
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If it binds when turning, it's not just the steering tube that's bent. The bearing cups must be misaligned as well, indicating some headtube damage. It's more than likely not dangerous, but I'd check things very carefully for main triangle damage and have the headtube faced and reamed at least.
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Old 06-20-13, 10:29 AM
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Originally Posted by cycle_maven View Post
If it binds when turning, it's not just the steering tube that's bent. The bearing cups must be misaligned as well, indicating some headtube damage. It's more than likely not dangerous, but I'd check things very carefully for main triangle damage and have the headtube faced and reamed at least.
+1^^, It would be a great idea to face the head tube, and the crown race seat as well, after re-bending.

Per the OP, this is a very subtle deformity, so I myself might have a go at getting it aligned.
But I still think that a framebuilder is the most qualified to do all of this, not that I wouldn't let one of the vanishing breed of competent pro shops take it on who are still conversent in the steel frame arena.

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cycle_maven, good point about the head cups being involved, I've had a couple of un-damaged PX10's that featured binding headset bearings when turned more than 30 degrees or so, but which didn't actually require correction, just a more careful headset adjustment was sufficient for my purposes.

Last edited by dddd; 06-20-13 at 10:33 AM.
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Old 06-20-13, 10:31 AM
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Originally Posted by cycle_maven View Post
If it binds when turning, it's not just the steering tube that's bent. The bearing cups must be misaligned as well, indicating some headtube damage. It's more than likely not dangerous, but I'd check things very carefully for main triangle damage and have the headtube faced and reamed at least.
Actually the bend is outward. I checked the frame it is fine. I post a photo later
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Old 06-20-13, 10:33 AM
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Originally Posted by Narhay View Post
Cost me $20 and a trip to the lbs.
I wish I could find one here that could do it.
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Old 06-20-13, 10:44 AM
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Originally Posted by dddd View Post
+1^^, It would be a great idea to face the head tube, and the crown race seat as well, after re-bending.

Per the OP, this is a very subtle deformity, so I myself might have a go at getting it aligned.
But I still think that a framebuilder is the most qualified to do all of this, not that I wouldn't let one of the vanishing breed of competent pro shops take it on who are still conversent in the steel frame arena.

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cycle_maven, good point about the head cups being involved, I've had a couple of un-damaged PX10's that featured binding headset bearings when turned more than 30 degrees or so, but which didn't actually require correction, just a more careful headset adjustment was sufficient for my purposes.
Just for fun, I also might have a go at it. How would you do it? I have successfully realigned steel frames.
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Old 06-20-13, 12:11 PM
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If you get your steerer tube straightened or replaced, make sure you have the head tube refaced, top and bottom, just to make sure things really line up in case there is some slight/not visible compression damage to the head tube......
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Old 06-20-13, 12:13 PM
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Replacing the steerer tube is pretty straightforward.

It's much better to cut off the damaged steerer and line bore the crown to remove the remaining material (the butted section of the existing steerer brazed in the crown) than to try heating it with a torch to remove it which could weaken the crown. The line boring should be done by a competent machine shop to ensure the bore is straight and true.

Once the remaining material is removed, braze in a new steerer tube.
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Old 06-21-13, 09:58 PM
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Originally Posted by Scooper View Post
Replacing the steerer tube is pretty straightforward.

It's much better to cut off the damaged steerer and line bore the crown to remove the remaining material (the butted section of the existing steerer brazed in the crown) than to try heating it with a torch to remove it which could weaken the crown. The line boring should be done by a competent machine shop to ensure the bore is straight and true.

Once the remaining material is removed, braze in a new steerer tube.

Thanks, but I wouldn't exactly call that approach easy.

Again, the bend in question is slight. Based on what I have read here, in what time I had, I tried the tree limb plus headset method and achieved some positive results. I will try again this weekend.
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Old 06-21-13, 10:11 PM
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Originally Posted by RFC View Post
Actually the bend is outward. I checked the frame it is fine. I post a photo later
Bike shops that deal in Vintage bikes almost always have a tool made by Parker that bends the tube back,,there is nothing to it
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Old 06-21-13, 10:21 PM
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Originally Posted by howeeee View Post
Bike shops that deal in Vintage bikes almost always have a tool made by Parker that bends the tube back,,there is nothing to it
That's what I would think. This should be no big deal.
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Old 05-05-21, 06:13 PM
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Slightly bent steerer tube

Hi, how did this work out for you? I have a slightly bent steerer tube myself.

Same thing, it's sticky on wide turns . I replaced the fork, but I want to do something with the old one with the bent steerer.

Thanks in advance.
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Old 05-06-21, 09:02 AM
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Originally Posted by LMBiker View Post
Hi, how did this work out for you? I have a slightly bent steerer tube myself.

Same thing, it's sticky on wide turns . I replaced the fork, but I want to do something with the old one with the bent steerer.
8 yr old Thread..!
Hopefully, someone can steer you in the right direction?
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Old 05-06-21, 11:25 AM
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