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Thread: Folding Bike Head Tube Crack

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    Default Folding Bike Head Tube Crack

    I have an aluminum Dahon Vitesse folding bike which is about 7 years old. It was recently pointed out to me that I have a hairline crack in my head tube. In the interim, I have put a hose clamp around the head tube to give it some strength, and to protect against failure. I have not noticed any increase in the length of the crack. I would like to either replace the bike or have the frame repaired. Is there anyone in the DC area that could do a welding repair on this aluminum head tube? Any other suggestions.

    Thanks.

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    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.

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    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

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    Quote Originally Posted by mstone View Post
    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
    Last edited by Vicegrip; 09-29-2014 at 11:42 AM.

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    DismalScientist is offline I really need to log off the internet and go for a ride.
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    Here's my thread on welding a steel frame. I think Bruce does Aluminum as well.
    http://bikearlingtonforum.com/showth...7-Frame-repair
    Here's the Craigslist ad:
    http://washingtondc.craigslist.org/n...684766625.html

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    Quote Originally Posted by DismalScientist View Post
    Here's my thread on welding a steel frame. I think Bruce does Aluminum as well.
    http://bikearlingtonforum.com/showth...7-Frame-repair
    Here's the Craigslist ad:
    http://washingtondc.craigslist.org/n...684766625.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.

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    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.

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    Quote Originally Posted by Vicegrip View Post
    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?

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    Quote Originally Posted by mstone View Post
    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...tanium-welding
    Last edited by Vicegrip; 09-30-2014 at 06:58 PM.

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    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.

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