Folding Bike Head Tube Crack

[mstone]

I think if you have a cracked aluminum head tube, you have a new bike coming. (I don’t think there is a practical way to repair it.) I would not ride it myself, as the failure mode is messy and painful.

[eminva]

If you are the original owner, call the bike shop where you purchased it. They can contact Dahon and most likely get you a new frame. If the shop is out of area, they can probably arrange it so that the new frame comes to a local dealer for your warranty work.

Liz

[Vicegrip]

@mstone 95523 wrote:

I think if you have a cracked aluminum head tube, you have a new bike coming. (I don’t think there is a practical way to repair it.) I would not ride it myself, as the failure mode is messy and painful.

Aluminum use for bike frames welds up well. If the frame can’t be replaced have it welds up by a competent welder using Tig. Grind out the crack, prep and clean and repair the area. A good Tig weld is the same as what the bike was made from. Repeat failures in the same area are most often due to poor prep or not removing the cracked metal past the start and finish of the crack. Poor methods can weaken the metal from too much heat or poor weld design. After repair be sure to inspect the area from time to time. In fact it would be a good idea to inspect the entire bike from time to time. Not all frame failures get noticed early. I weld up aluminum and don’t see re worked area fail at a rate higher than new work

[DismalScientist]

Here’s my thread on welding a steel frame. I think Bruce does Aluminum as well.
http://bikearlingtonforum.com/showthread.php?5067-Frame-repair
Here’s the Craigslist ad:
http://washingtondc.craigslist.org/nva/bop/4684766625.html

[cyclingfool]

@DismalScientist 95562 wrote:

Here’s my thread on welding a steel frame. I think Bruce does Aluminum as well.
http://bikearlingtonforum.com/showthread.php?5067-Frame-repair
Here’s the Craigslist ad:
http://washingtondc.craigslist.org/nva/bop/4684766625.html

Another vote for Bruce, assuming he does aluminum, which I think he does if memory serves from talking with him. He did a quality welding job on my chro-moly 1995 Trek 830 frame, which had broken near one of the rear dropouts, for a very fair price.

[hozn]

FWIW, a buddy of mine had Bruce weld a titanium frame. It did not go so great. Bruce remarked at how awesome the weld came out by noting the rainbowing. Apparently for titanium that is exactly what you do not want to see in a weld, since it indicates contamination. Anyway, my buddy deemed it unsafe to ride and threw it out. In that case the gamble was worth it, but if you have a warranty option, I’d do that first.

[mstone]

@Vicegrip 95561 wrote:

Aluminum use for bike frames welds up well

Even a hoop stress fracture in a seamless head tube? Last time I looked at this there weren’t many people who wanted to touch that. This repair will also require machining the weld for the headset, to add a bit more labor. Can all of that be done safely and economically if a complete replacement off ebay or whatever would only cost a couple hundred?

[Vicegrip]

@mstone 95574 wrote:

Even a hoop stress fracture in a seamless head tube? Last time I looked at this there weren’t many people who wanted to touch that. This repair will also require machining the weld for the headset, to add a bit more labor. Can all of that be done safely and economically if a complete replacement off ebay or whatever would only cost a couple hundred?

8 noted that replacement was a first choice. I also noted that welding is a viable method when done well. I missed the image of the crack in in question and seem to have missed that it ran through a bearing

Ti does not transfer heat well and backgassing is critical it is easy ot overheat and cook TI and you need to take care with initial amps and running amps. once you establish a puddle ramp down on amps or you can overheat. Sometimes a rainbow only means the weld was not bufed up if it is not past the brown range. Lovely blues and above are not good.
Not saying this the case here but i have noted a lot of missinformation about welding and weld related repairs gets repeated as gospel by non weldors.

This is my go to resource when starting into a new method, metal or run into issues during a build or repair. http://www.millerwelds.com/resources/articles/TIG-gtaw-titanium-welding

[hozn]

Thanks for the info, Vicegrip. Yeah, I don’t know first-hand that Bruce would not so a good job, only that there was some seeming issue with the ti welding work, so I might have been skeptical of the TIG welding capabilities — if there is any relation to aluminum welding. I have no idea what I am talking about Of course, you might also be right that it was just a buffing issue, etc.

[mstone]

@Vicegrip 95718 wrote:

Not saying this the case here but i have noted a lot of missinformation about welding and weld related repairs gets repeated as gospel by non weldors

That would be me, that’s why I was curious if things something had changed since I threw out my frame.

[Vicegrip]

@hozn 95719 wrote:

Thanks for the info, Vicegrip. Yeah, I don’t know first-hand that Bruce would not so a good job, only that there was some seeming issue with the ti welding work, so I might have been skeptical of the TIG welding capabilities — if there is any relation to aluminum welding. I have no idea what I am talking about Of course, you might also be right that it was just a buffing issue, etc.

Not having a good result with Titanium is not reason enough to disregard other work in other metals in my book. In stainless light straw to light rainbow is often a desired result. Ti is its own metal. Love it on one hand hate it on the other. Aluminum is easy peasy.

[Crickey7]

For a while in the late 1980’s through late 1990’s, Trek made road bikes with bonded aluminum frames (1200 series). I’d be very wary of one of these.

[Harry Meatmotor]

Why not just call Dahon find a local dealer and get a warranty replacement frame? Around here you’re probably not going to find a machine shop that’ll be willing to clean, grind/prep, TIG, grind back, face and bore the HT for less than $200.

[Egoodman]

Thanks everyone for the advice on what I should do next. I will try to contact the welder on Craigslist and see if a repair is do-able. Attached is a photo if the head tube crack.

[Author]

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