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Cracked Kona frame downtube

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Cracked Kona frame downtube

Old 05-17-23, 05:57 AM
  #1  
Breadfan
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Cracked Kona frame downtube

I don't know if this is repairable so I thought I would ask. It's cracked pretty good.






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Old 05-17-23, 07:06 AM
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That tube is not repairable. It could be replaced, I doubt replacing it would be economic though
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Old 05-17-23, 01:50 PM
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FWIW: as it is now I would not ride that frame on a bet. Not even around the block.

That downtube is cracked most of the way through. If it gives while being ridden, good chance you'll become well acquainted with terra firma - possibly face first.
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Old 05-17-23, 02:07 PM
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Post a close-up side view and perhaps a bottom view of the top tube at about the same distance from the head tube. 2" or 3" from the head tube.
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Old 05-17-23, 04:59 PM
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To my eyes this looks to be about where the butt transition is. While not common, this location (at the end of the butt) does see some cracks at times. There could have been an internal surface "feature" from the tube's being drawn over a mandrel. Sometimes this butt end point is so close to the joint that the heat affected zone travels past it. Sometimes "braze ons" are attached on this thin butt section. If either were the case and the brazing was a bit overheated that thin walled section can fail sooner than the rest of the frame.

Normally I would suggest seeking warranty replacement if Breadfan is the original owner. Or maybe a "crash replacement" discount. But the amount of rust on display makes me pause of that advice. Andy
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Old 05-17-23, 08:49 PM
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YIKES!

What was the mechanism of the injury?
Is that rust from the inside out?
How long has this been cooking?
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Old 05-17-23, 11:00 PM
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My interpretation is that it could be hard front end crash damage from quite some time ago. And, thus the questions about the top tube.
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Old 05-18-23, 07:18 AM
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Originally Posted by CliffordK
My interpretation is that it could be hard front end crash damage from quite some time ago. And, thus the questions about the top tube.

The photos don't obviously show any top tube damage, or even down tube deformation other than the crack. One can follow the light reflection "lines" and not see any dog legging from a bend's focal point. The first photo is the best view for this. I see no need for more shots.

I am still curious about this bike's history and how it became so deeply (the rust doesn't look to be a surface type that can be wiped off with fine sanding) rusted. I doubt the rust was the primary cause of this crack but it sure didn't help And (who has replaced a couple of frame tubes from rust through over the years)
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Old 05-18-23, 07:59 AM
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I dunno, sure looks like it had front end damage to me. I don't know why the tube would pucker like that if it hadn't been run into something. That also explains the crack, this doesn't look like lightweight steel.
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Old 05-18-23, 09:50 AM
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Originally Posted by unterhausen
I dunno, sure looks like it had front end damage to me. I don't know why the tube would pucker like that if it hadn't been run into something. That also explains the crack, this doesn't look like lightweight steel.
My take on the puckering of the crack at the tube's underside is that it could be from the two faces being forced against each other and possibly not from an impact. But my comments were about the top tube not showing any obvious damage and thus no need for more viewing angles. Since I'm not the owner or the person who they are asking to repair this frame my opinions are just that, speculative opinions.

I've seen many bikes that have had only one tube showing the classic kinking/bulging after a frontal impact so I could easily be wrong on this one. Andy
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Old 05-18-23, 10:28 AM
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I have seen a similar rust pattern on a bicycle that was hung on a non-padded steel hook near salt water. But no crack.

I keep wondering about the inside of the frame. I have seen a few post 2000's bicycle frames that looked terrible on the inside and yet had intact paint on the outside.

If it was my bike I would do one of my get down dirty, "Driveway" repairs, of stripping the paint, inspecting the frame inside and out, and then brazing on a sleeve.

I don't think it would be economical (safe) to pay someone to repair this frame...
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Old 05-18-23, 10:47 AM
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I bought this frame cheap, it had a lot of usable parts on it, I have no idea of the history. The parts (worn but still good) however lead me to believe that this bike was just rode very, very hard leading to the cracked down tube. I may just hang it up and one day have the down tube replaced, or just get a sleeve if its not too expensive. In other words, find someone I can trade with to bring the cost down. It wouldn't make sense to over spend on a cracked frame, I'm not doing that.
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Old 05-18-23, 12:30 PM
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It's really difficult to ride a bike hard and long enough to crack in this particular location. Cracks happen near a stress riser, generally at the edge of a weld. If this was a fatigue crack, it probably would have started much nearer to that cable guide. I generally expect fatigue cracks on the seat tube joints. Ether on the top of the seat tube/top tube joint or at the bb shell. I think that there has to be a problem with a weld to get a crack at the head tube/down tube joint.
Of course, there always could be material defects. Some brands were known for it bitd.
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Old 05-19-23, 04:07 AM
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Originally Posted by Hondo6
FWIW: as it is now I would not ride that frame on a bet. Not even around the block.

That downtube is cracked most of the way through. If it gives while being ridden, good chance you'll become well acquainted with terra firma - possibly face first.
Yes, although I actually rode a bike home carefully about 6 miles after a DT snapped in pretty much that place (not a frame I built I should add).
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Old 05-19-23, 04:09 AM
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Originally Posted by unterhausen
It's really difficult to ride a bike hard and long enough to crack in this particular location. Cracks happen near a stress riser, generally at the edge of a weld. If this was a fatigue crack, it probably would have started much nearer to that cable guide. I generally expect fatigue cracks on the seat tube joints. Ether on the top of the seat tube/top tube joint or at the bb shell. I think that there has to be a problem with a weld to get a crack at the head tube/down tube joint.
Of course, there always could be material defects. Some brands were known for it bitd.
It looks like it's cracked where the butting ends. Maybe a manufacturing problem-- the mandrel left some scratches on the inside, or the wall thickness wasn't uniform and too thin in some places? But also it's very rusty.

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Old 05-19-23, 04:52 AM
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I'm pretty sure the rust happened after the bike was scrapped. The person that I got it from said it had been sitting in the back of a truck for a while.
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Old 05-19-23, 02:23 PM
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Originally Posted by unterhausen
I dunno, sure looks like it had front end damage to me. I don't know why the tube would pucker like that if it hadn't been run into something. That also explains the crack, this doesn't look like lightweight steel.
According to the decals it is a 1997-1998 model not a Kilaeua in Reynolds 631 nor an Explosif in Reynolds 853, not sure if it is a road bike or a MTB but I do agree with you, it must be a basic crmo steel frame.
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Old 05-19-23, 02:31 PM
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Originally Posted by guy153
It looks like it's cracked where the butting ends. Maybe a manufacturing problem-- the mandrel left some scratches on the inside, or the wall thickness wasn't uniform and too thin in some places? But also it's very rusty.
Normally Kona steel frames aren't prone to cracking, this must be the first time I have seen one in such shape.I ride a 1997 Kona Kilaeua in Reynolds 631 and never crashed it. For the note some of the Kona Easton Elite full and Scandium suspended frames were prone to cracking. Maybe the tubes weren't treated at all against corrosion nor even air hardened.I would rather buy a very good kona high grade steel frame on ebay as a replacement.
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Old 05-19-23, 05:57 PM
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Itís a 2013.

https://2013.konaworld.com/bike.cfm?content=rove



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Old 05-19-23, 11:58 PM
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Originally Posted by Breadfan
thanks for sharing, my mistake,road /gravelbike indeed but in the description of the frame no mention of air hardened or treated againt corrosion frameset, even the front fork legs are rusty and in another one of the other photos, the headset tube is rusty as well.I think that you will spend too much time and money for trying to fix this one.

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Old 05-20-23, 12:49 AM
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Originally Posted by georges1
Normally Kona steel frames aren't prone to cracking, this must be the first time I have seen one in such shape.I ride a 1997 Kona Kilaeua in Reynolds 631 and never crashed it. For the note some of the Kona Easton Elite full and Scandium suspended frames were prone to cracking. Maybe the tubes weren't treated at all against corrosion nor even air hardened.I would rather buy a very good kona high grade steel frame on ebay as a replacement.
Air-hardening is just something that 631 and 853 do after you weld them. It means that as the metal cools down after welding it gets stronger. That is the special feature of those alloys. They heat-treat themselves in the weld-zone. It's not something you do or don't do. Some people add corrosion treatments to the insides of frames after they build them but from the factory the tubes have a kind of black residue inside them (probably oil and stuff from the mandrels, perhaps a bit of mill scale) which is pretty corrosion resistant. You wouldn't expect a frame to rust from the inside except in places where water collects. That's why this is an odd location for it to happen because water doesn't collect there. But people are saying it was stored for a long time after the failure so it may have just rusted after it broke because that exposed clean metal.
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Old 05-20-23, 01:13 AM
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Originally Posted by guy153
Air-hardening is just something that 631 and 853 do after you weld them. It means that as the metal cools down after welding it gets stronger. That is the special feature of those alloys. They heat-treat themselves in the weld-zone. It's not something you do or don't do. Some people add corrosion treatments to the insides of frames after they build them but from the factory the tubes have a kind of black residue inside them (probably oil and stuff from the mandrels, perhaps a bit of mill scale) which is pretty corrosion resistant. You wouldn't expect a frame to rust from the inside except in places where water collects. That's why this is an odd location for it to happen because water doesn't collect there. But people are saying it was stored for a long time after the failure so it may have just rusted after it broke because that exposed clean metal.
I totally agree with you
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Old 05-20-23, 02:35 AM
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So we are under the consensus that the tube cannot be replaced? Or, for economics sake, a sleeve would not hold up? Iím not too worried about the surface rust on the head tube. Thatís all it is.
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Old 05-20-23, 05:01 AM
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The cracked tube is reminiscent of one in a photo on this page: 12 High-End Frames in the EFBe Fatigue Test

Quick recap of the test and results: high-end steel, aluminum, titanium, and carbon frames were subjected to carefully designed fatigue testing. To the surprise of the testers, all of the tested steel and titanium frames failed; only two aluminum frames and one carbon frame survived.

The testers concluded that small tweaks in the design of the failed frames and/or more-careful heat control during welding or brazing would likely have enabled the failed frames to survive the test.

That said, the crack seen in the opening post is puzzling, since it's not all that close to the braze-ons. Maybe it was just the effect of the combination of many years of hard use and a too-abrupt transition of wall thickness at the butt in the tube, as speculated in a post above.

The text accompanying the photo:

The myth of indestructibility collapses: Relatively early, considering the price and the high expectations, a crack spiraled around the down tube of the Merlin Team Road titanium frame. Point of origin: the small weld at the shift-lever boss.

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Old 05-20-23, 08:30 AM
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A sleeve just introduces more problems. The tube can be replaced, but it will cost you.

Whoever came up with the "lifetime bike" label for Ti frames was a marketing genius, but really didn't have any technical justification for it. After my experience with Teledyne, I was a Ti skeptic, and there are plenty of cracked welds in Ti frames to prove that it doesn't last forever. All that has to happen is someone fails to purge properly or make a mess of a weld, and poof, kersplode!
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