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Old 11-20-07, 02:27 PM   #1
bcart1991
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Head tube crack - Repairable?

Upon pressing in a headset, the head tube of one of my frames developed a crack. It's not terribly large (approx. 1/4" long), starting at the bottom of the tube, on the front side (basically looking straight forward).

The frame is aluminum, so I'm wondering if this would be repairable by a competent welder, who could potentially fill in the crack, and grind/sand the tube smooth/round.

No chance at a warranty or replacement.

Thoughts?

Kotter
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Old 11-20-07, 03:06 PM   #2
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While it's possible to weld the crack, it's likely the head tube will crack again, probably next to where it was welded. It would be a temporary and somewhat risky fix at best.
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Old 11-20-07, 03:20 PM   #3
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That's what I was thinking. I'll be keeping a close eye on it. It should be rideable until I find a suitable replacement.
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Old 11-20-07, 03:34 PM   #4
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Not reliably repairable. My condolences.

Your frame has 'ceased to be'. It is an 'ex-frame'.
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Old 11-20-07, 04:03 PM   #5
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Originally Posted by bcart1991 View Post
It should be ride able until I find a suitable replacement.
This crack could result in a sudden failure. Having the fork come out at an inopportune time can be very bad. Would you be so kind as to name my as a beneficiary on your life insurance? Really though, I would not ride it at all but I like to err on the side of caution.
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Old 11-20-07, 07:13 PM   #6
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Quote:
Originally Posted by bcart1991 View Post
Upon pressing in a headset, the head tube of one of my frames developed a crack. It's not terribly large (approx. 1/4" long), starting at the bottom of the tube, on the front side (basically looking straight forward).

The frame is aluminum, so I'm wondering if this would be repairable by a competent welder, who could potentially fill in the crack, and grind/sand the tube smooth/round.

No chance at a warranty or replacement.

Thoughts?

Kotter
I had that happen on a brand new Serotta in '92 I thought but it turned out to be just the paint and not metal.
Are you sure it is the actual tube? Just asking, if youve pulled the race to check or can actually see the depth sorry to hear it. I always hope for the superficial first.
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Old 11-20-07, 09:26 PM   #7
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Quote:
Originally Posted by bcart1991 View Post
Upon pressing in a headset, the head tube of one of my frames developed a crack. It's not terribly large (approx. 1/4" long), starting at the bottom of the tube, on the front side (basically looking straight forward).

The frame is aluminum...
If you're going to keep riding it, it would be a good idea to drill a small (3/16"?) hole just where the crack ends. This will stop the sharp end of the crack from acting as a stress riser. If you don't do that, the crack is liable to grow.

The poster who wrote "This crack could result in a sudden failure." is a well-meaning alarmist. The location of the crack means that it is mainly stressed in static weight bearing. It carries no share of braking load.

If the problem does get worse (the crack grows) it will give you plenty of warning. It will feel as if the headset is misadjusted (too loose) LOOOOOOONG before there's any chance of "sudden failure."

Sheldon "Seen This Before" Brown
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Old 11-20-07, 10:53 PM   #8
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Sheldon, thank you for your knowledge and real experience, it is very much appreciated.

You rock, dude!
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Old 11-21-07, 06:59 AM   #9
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If you're going to keep riding it, it would be a good idea to drill a small (3/16"?) hole just where the crack ends. This will stop the sharp end of the crack from acting as a stress riser. If you don't do that, the crack is liable to grow.

The poster who wrote "This crack could result in a sudden failure." is a well-meaning alarmist. The location of the crack means that it is mainly stressed in static weight bearing. It carries no share of braking load.

If the problem does get worse (the crack grows) it will give you plenty of warning. It will feel as if the headset is misadjusted (too loose) LOOOOOOONG before there's any chance of "sudden failure."

Sheldon "Seen This Before" Brown

I stand corrected. "well-meaning alarmist"? Guilty as charged. I always prefer to err on the side of caution on things like this. Good point on the drilled hole to mitigate a stress riser.
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Old 11-21-07, 07:15 AM   #10
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Any possibility of putting a hose clamp or clamps around the head tube to reinforce.
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Old 11-21-07, 07:38 AM   #11
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Drilling the hole is a good idea. I can *just* see the HS race through the crack in the right light, so I know it's not just paint. My LBS concurred, and has also pretty much givent eh same words of wisdom here, save the "well-meaning-alarmist."

I know it's not a stress-bearing area, so it wil be okay for a while.

I actually thought about a hose clamp, but there's not enough space to fit it in there.

Thanks for all the advice everyone.

Kotter
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Old 11-21-07, 11:36 AM   #12
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Is the tube long enough so you could cut it off at the point of the crack? A quarter inch shouldn't change the dynamics of the frame a noticable amount.
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Old 11-21-07, 01:05 PM   #13
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The frame is a 52, so not much wiggle room.
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Old 11-21-07, 01:21 PM   #14
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How about popping the bottom cup back out and then reinstalling it with the addition of some epoxy. Might serve as an additonal structural element to help hold it all together.
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Old 11-21-07, 03:15 PM   #15
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My last suggestion would be to weld a curved AL plate over it like patching a tire.
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Old 11-21-07, 03:33 PM   #16
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If it isn't a stressed area, why did it crack in teh first place?
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Old 11-21-07, 04:04 PM   #17
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My last suggestion would be to weld a curved AL plate over it like patching a tire.
Can't properly weld without heat treating the entire frame again.
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Old 12-07-07, 08:04 AM   #18
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does the word"measure" mean anything to you?,the pressed in cups are a "press fit".the cups cannot be more than.2mm bigger if they are you risk cracking the head tube!!!! this is a job for a professional bike machinic,not a home machinic.i have seen more bicycles destroyed this way. headset installation is the most dangerous to the bike if you don't know what your doing.
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Old 12-07-07, 08:21 AM   #19
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Again, but in English, please.

The frame was at the shop when it happened. Thanks for the input though, cockbite.
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Old 12-07-07, 11:39 AM   #20
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As Sheldon said,drill a small hole at the end on the crack,that will stop the crack from getting worse.If there's room for it,you could make a small steel or aluminum ring and shink fit it on the head tube.If your lucky,you can make the ring so it covers the crack and the hole both.
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Old 12-07-07, 08:43 PM   #21
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Everybody seems to overstate the importance of heat treating aluminum before it's welded. I unfortunately have weld all day and trust me, on thin walled aluminum there is no need to preheat. Getting the paint off and the part clean woud be far more important. If your wanting a cosmeticly pleasing repain, don't weld it unless you're planning on repainting. You'll wind up boiling all the paint off at least 1.5" around the welded area.
Have you considered the possiblity of not being able to get the diameter of the head tube back to the original size? Sounds like you've managed to stretch it.
Good luck
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