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Crack in the head tube! Trek 600

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Crack in the head tube! Trek 600

Old 07-22-20, 04:59 PM
  #26  
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Originally Posted by JohnDThompson View Post
IIRC, that model used a Nikko one-piece bulge-formed head tube (the "lugs" were integral with the head tube), rather than separate head lugs and head tube.

Drop the fork and look inside the head tube. If all you see is a couple small vent holes, then it has the three-piece head lugs/head tube. If instead you find large openings the width of the inserted tubes, then you have the one-piece head tube.
I will check when I strip the bike and hopefully report back if I remember!
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Old 07-22-20, 05:00 PM
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Originally Posted by repechage View Post
Take it to a Trek dealer and ask for a warranty replacement.

repairable as noted, not economical
I have seen this type of failure before - typical was loaded touring involved and high miles.
Ha! Yes, this bike seems to have done a stint as a city bike in New York, so rust issues elsewhere make it an unlikely candidate for heroic measures.
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Old 07-22-20, 08:01 PM
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Old 07-23-20, 10:29 AM
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If you have an affordable framebuiler nearby, die grind out that tube and have a framebuilder silver in a new one.

It'll forever be a torched-up mutt and an expensive fix if you decide to paint, but you'll still be N+1 frame

-Kurt
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Old 07-23-20, 10:48 AM
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I think that was mine before it was yours, right?? What a bummer. That was a great riding frame, I still have a photo of it at Coney Island on my work desktop.
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Old 07-24-20, 05:35 AM
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Originally Posted by lostarchitect View Post
I think that was mine before it was yours, right?? What a bummer. That was a great riding frame, I still have a photo of it at Coney Island on my work desktop.
Yes! I did a lightweight indexing vintage mtb mech build with an ultegra road triple. My kids both loved it literally to death! It had a good life and as you can see did a farewell tour out to Orient Point. We are mourning it like a pet, it was that sweet of a bike.

Even though it eventually got used up, it was one of the best bike buys I have made.
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Old 07-24-20, 05:37 AM
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Originally Posted by cudak888 View Post
If you have an affordable framebuiler nearby, die grind out that tube and have a framebuilder silver in a new one.

It'll forever be a torched-up mutt and an expensive fix if you decide to paint, but you'll still be N+1 frame

-Kurt
If my six foot tall youngest would not be too tall for it by spring, i would do so.
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Old 07-24-20, 07:30 AM
  #33  
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Originally Posted by Standalone View Post

This photo from before our tour shows the crack that I didn’t notice... it runs along the entire lower lug and as you can see wraps around to the front. I got in there with a dental pick type tool and it’s not like a deep or open crack, but it looks to me like the HT is done.

Posting for conformation and commiseration. I built this up for my sons and it saw a lot of great use over four or five years . My favorite and most challenging build with a mix of ultegra 9sp, flat bar, and rusty parts bin MTB mech. It was super light and ran great!

it looks like the tube was weakened by the brazing.
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Old 07-27-20, 03:01 PM
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Replacement located! I had saved this Nishiki Riviera GT years ago from a local kid who had started to sand the beautiful finish off the seat stays and seat tube. I hit it with some paint and gave it to a friend. He meet real used it except as a guest bike. He’d offered the other week to give it back so I picked it up from him. Some wheel trueing and handlebar tape and my son digs it! We worked on DT shifting and he took right to it. Time for some tri flow and racks/fenders. The fitting on the brake bridge is vertical instead of horizontal so a fender will be tricky but this thing has dual braze ons front and rear. Love it.



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Old 07-27-20, 03:18 PM
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Originally Posted by Standalone View Post
Replacement located! I had saved this Nishiki Riviera GT years ago from a local kid who had started to sand the beautiful finish off the seat stays and seat tube. I hit it with some paint and gave it to a friend. He meet real used it except as a guest bike. He’d offered the other week to give it back so I picked it up from him. Some wheel trueing and handlebar tape and my son digs it! We worked on DT shifting and he took right to it. Time for some tri flow and racks/fenders. The fitting on the brake bridge is vertical instead of horizontal so a fender will be tricky but this thing has dual braze ons front and rear. Love it.




Great bike, but isn't it a smidge small for him? And if it isn't already it looks like he'll outgrow it in about 5 minutes. haha
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Old 07-27-20, 03:33 PM
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Originally Posted by tricky View Post
Great bike, but isn't it a smidge small for him? And if it isn't already it looks like he'll outgrow it in about 5 minutes. haha
Yep! But there are like a half dozen 25” frame bikes here for him next year. Trek 620 already built and a 520 with some 105 9sp that just needs cables, housing and chain.

The Nishiki’s TT is actually an inch longer than his ’83 Trek. This will last the summer and doesn’t cost me anything. Gonna move the seat up a bit after he gets used to DT shifting. Or who knows something else might fall in my lap. You know how n+1 goes
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Old 07-27-20, 06:20 PM
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I put fenders on a mountain bike with the similar single hole, all I did was make an L bracket and bolt it to both the frame and standard fender bracket. Not the most elegant but it worked.
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Old 07-27-20, 08:59 PM
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Originally Posted by Standalone View Post
Yes! I did a lightweight indexing vintage mtb mech build with an ultegra road triple. My kids both loved it literally to death! It had a good life and as you can see did a farewell tour out to Orient Point. We are mourning it like a pet, it was that sweet of a bike.

Even though it eventually got used up, it was one of the best bike buys I have made.

Glad it went to a good home and got some good use! Yes, it was a great bike, I was often sorry I sold it.

I periodically look around for a "new" vintage Trek for myself. One of these days I'll find one I like that isn't priced out of my league!

Here is "our" bike at Coney Island some time back.

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Old 11-05-21, 10:25 PM
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My Trek 61x from 1982 just broke in exactly the same spot!




The crack goes from the top of the lower head lug, down about halfway, and then over toward the center. Kind of eerie the similarity to the OP's crack, and in similar models of Trek from similar years!

My observation is that the head tube on mine is reamed out to near the headset cup diameter, extending up way farther than it needs to be, definitely past the head lug. Why? I don't know!

I noticed the crack because my headset was weirdly binding after I made a new fork for the bike. I knew the fork was perfect, so I started to investigate the frame. Also, the old fork had a bad brake-judder and then it broke, so expected the judder to be fixed with the new fork, but to my surprise, it was just as bad so the problem seems less likely to be the fork and more likely the frame or something else.

I plan to repair this. I will buy a 1-1/4" OD, thick walled mild steel tube and turn it to whatever diameter this thing is reamed to. Then I'll braze it in. As long as the tube's ID is bigger than about 1.05" (the ID of an alu headset cup), I should be good.
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Old 11-16-21, 03:37 PM
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The one-piece headtube is not reparable by internally sleeving. Here is why:



Basically, the one-piece headtube appears to have been bored out, which would appear to make it ideal to sleeve and braze. But the crack goes from the nicely-bored portion of the headtube into a bulged-out portion of the tube, where the "faux lug" portion is on the outside. I cannot reliably fill that with braze and expect it to be strong, nor can I probably get it clean enough since the frame won't fit inside the sandblasting cabinet. So, I'm going to have to replace the headtube and bottom/top lugs.

It's interesting that the tube has been bored so deep and to such an extent beyond the headset cup - and so off-center, too! The crack extends from the thin-walled bored-out portion of the tube, into the shoreline of the bulged faux-lug area. This is a possible stress riser, but the bore has thinned the wall considerably as well. One nagging question I have is, why did they bore these out so much? And is the boring what caused the cracks? Or is it the bulge where the faux lug was formed? I may never know.

Good news is, the down and top tubes are fairly nicely coped and will easily take the new head tube and lugs.



These tubes are bronze brazed in, as far as I can tell. The guy at Franklin Frame said he likes to melt out bronze brazing, but it's tricky without a rosebud tip and using up a ton of oxygen. I am probably going to slice the lugs in a couple places with a hacksaw, then get it moderately hot and peel them off with needlenose vise grips.

But before all that, I'll probably just ride the bike for a while, until I get a proper backup steed going.
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Old 11-17-21, 03:54 AM
  #41  
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Cracked Head Tube

Originally Posted by Standalone View Post
This photo from before our tour shows the crack that I didn’t notice... it runs along the entire lower lug and as you can see wraps around to the front. I got in there with a dental pick type tool and it’s not like a deep or open crack, but it looks to me like the HT is done.

Posting for conformation and commiseration.




The cracks in the head tube are most likely due to material flaws in the steel...

Many bike manufacturers cheaped out on head tube material using low grade seamed gas pipe carbon steel tubing. I've seen this on even some top name frames. Head tubes were generally considered to be low stress areas of a frame so a good place to save a few pence, pennies, centimes, lira etc. I would be surprised if TREK did that???

Reynolds and others produced 1 1/4" (31.75mm) and metric 32mm head tube material in nominal 20 foot lengths for manufacturers who bought tubing in bulk. Same thing with 4130 Aircraft Tubing in the US.

The lengths were "nominal" because the ends of high quality tubing were trimmed off to remove impurities and potential flaws in the metal from the drawing and subsequent re-heat treatments so the actual lengths varied from tube to tube.

Trimming the ends was not as much so with cheap seamed tubing used for inexpensive non critical applications.

This illustration show various types of cracks in the end of a seamed tube. The drive side photo shows multiple cracks from possible lamination and inclusions.

Head tubes on frames with simple lugs are easy for a frame builder to replace. Grinding and peeling the old tube out of the lugs is probably a better way to go the heating and remelting the brazing material because the remelting temperature is higher than the original melting point - look up eutectic effect.

Back in the early days of TREK they advertised that they were using silver to braze some or all of their frames. If this frame was silver brazed it would be a lot easier to remelt.

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Old 11-17-21, 04:27 AM
  #42  
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One Piece Bulge Formed Headset

Originally Posted by JohnDThompson View Post
IIRC, that model used a Nikko one-piece bulge-formed head tube (the "lugs" were integral with the head tube), rather than separate head lugs and head tube.

Drop the fork and look inside the head tube. If all you see is a couple small vent holes, then it has the three-piece head lugs/head tube. If instead you find large openings the width of the inserted tubes, then you have the one-piece head tube.
John, scarlson that was a consideration too but what appears as a seam down the back of the head tube and the crisp shoreline of lug to head tube joint suggested that it was made with separate head tube lugs. But as you say, pulling the fork will answer the question.

Either way, one-piece bulge-formed head tube or lugs, the cracks are mostly due to a flaw in the steel.

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Old 11-17-21, 08:17 AM
  #43  
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Originally Posted by unterhausen View Post
I fixed a bike like that by replacing the head tube. It was nearly impossible to see the crack from the outside, but it was pretty clear from the inside. It's a little weird, I figured there was some thinning of the tube during filing and the frame might have been built under tension.
True. I had a steel lugged Italian that I loved with cracked head tube and found a local frame building with tons of steel experience replace it. It was less than $200 for a bike that I loved riding and now has given another year of wonderful riding with the replacement. Found HT decal and repainted myself and nobody notices unless I point out.
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Old 11-17-21, 08:24 AM
  #44  
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Yes indeed, head tube fractures do occur. I did not attempt to salvage the frame in that link.

Head tube, we have a problem.

If ever I can get to building a frame, it will be overbuilt (with an oversized head tube, heavy duty rear dropouts etc., for example)

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Old 11-17-21, 08:50 AM
  #45  
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This is the first I'm hearing of Trek headtube cracking. Would an '83 Trek 630 fall under the models affected by this?
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Old 11-17-21, 08:54 AM
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Originally Posted by verktyg View Post
but what appears as a seam down the back of the head tube and the crisp shoreline of lug to head tube joint suggested that it was made with separate head tube lugs. But as you say, pulling the fork will answer the question.

Either way, one-piece bulge-formed head tube or lugs, the cracks are mostly due to a flaw in the steel.
If you look at the pictures of the interior of the bulge formed head tube, you see that what looks like a lug is actually pushed out from the head tube assembly material. And it looks pretty crude from the inside. So they have taken smooth material and made a sharp transition. It's pretty sharp transition on the inside as well. That sharp transition is a great place to start a crack, and by bulge forming it they have thinned the material out quite a bit. I imagine there is some variation in the bulge forming process that leads some of these to crack when others don't. I'm not sure I believe there is any flaw in the material itself, whatever that might mean. Although rust wouldn't help. I imagine the material had to be fairly uniform to survive the bulge forming process without tearing. A lugged head tube is somewhat redundant structurally, they took some of the redundancy out of that by making it one piece.

Cracks will definitely follow along the shoreline of a lug as long as that's perpendicular-ish to the load. At some point it will veer off as it did in the case of the red and silver bike. That's because the shoreline was going in the direction of the load so there was nothing to drive the crack in that direction. But since there was a sharp crack end there, it was natural for it to start around the circumference of the "head tube." In fatigue, it's typical to have multiple cracks that end up coalescing to one crack. Particularly at initiation. I always think of it as one crack winning the race for dominance. That veering process is similar to initiating a new crack, but whichever crack wins resumes long crack behavior pretty quickly.

I have to say this is a really good simulation of a lugged assembly, it certainly fooled me. I have seen some different Trek models where it was obviously fake, not that there is anything wrong with that. If you are surprised by Trek using a piece of low end steel for a head tube, you probably would be even more surprised to find the lugs and head tube are one piece formed out of a piece of low-end steel.

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Old 11-17-21, 09:56 AM
  #47  
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With classic construction the head tube runs clear through, okay maybe with some gas vent holes, with this cost savings scheme, there is no supporting wall at the end of the top or downtube.
While minor, I would think it would lead to additional flex, add in a stress riser by abrupt metal forming and this design was meant to fail at some point.
Planned Obsolescence.
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Old 11-17-21, 11:01 AM
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Originally Posted by repechage View Post
With classic construction the head tube runs clear through, okay maybe with some gas vent holes, with this cost savings scheme, there is no supporting wall at the end of the top or downtube.
While minor, I would think it would lead to additional flex, add in a stress riser by abrupt metal forming and this design was meant to fail at some point.
Planned Obsolescence.
I thought the same thing, these frames most likely have a sell-by date. I'm sure that 40 years ago the idea that they might fail in 40 years seemed like an okay problem to have. If they even thought about it. Trek has been good about honoring their warranty, but if they do you aren't going to get a lugged steel bike.

Some builders think that making vent holes too big leads to cracking, and that seems legit to me. Others make elaborate cutouts that are much larger and I haven't seen any reports of failures from that. So who knows? One thing is that hole quality is important in fatigue, and it's harder to drill a big hole with smooth walls. That probably contributes to the disparity in fatigue resistance of vent holes, if that really is a significant issue.
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Old 11-17-21, 11:16 AM
  #49  
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I have a 1984 610, based on SN from Vintage Trek. It has the one piece head tube/lugs. No sign of cracks and the transitions internally look OK. There also appears to be a seam in the front side of the bore. Does not appear to be bored all the way through.
At least I have a 1984 760 as an alternative Trek.

Note the lack of braze material
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Old 11-17-21, 07:17 PM
  #50  
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Originally Posted by SJX426 View Post
I have a 1984 610, based on SN from Vintage Trek. It has the one piece head tube/lugs. No sign of cracks and the transitions internally look OK. There also appears to be a seam in the front side of the bore. Does not appear to be bored all the way through.
Those one-piece head tubes start out as flat sheet metal. Lug spigots are pressed into the sheet, and the pseudo lug shoreline on the head tube pressed on at the same time. Unfortunately, that pseudo shoreline creates a stress riser that can eventually crack. The sheet is then rolled into a tube and welded closed in the front where you see the seam. This was all done in Japan by Nikko, as well as the boring of the inside of the tube. Trek milled and faced the ends of the head tube after brazing for the headset pieces.
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