Broken Frame

Discussion in 'General Bike Discussion' started by Dan_3, May 8, 2009.

  1. Dan_3

    Dan_3 Guest

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    After 20 years, my Motobecane snapped one of the struts that connect the bottom bracket to the back wheel hub. It broke right where it connects to the back hub. Is it at all conceivable that I'd be able to have this piece welded so that it I could ride the bike again, or am I going to have to ditch the frame as one bike shop told me?
     
  2. littleblackxj

    littleblackxj New Member

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    Depends what the frame is made out of. If it's aluminum, or cast iron then say goodbye. If it's steel then you can weld it. If it's stainless steel, you will need special wire.
     

  3. Grape Ape

    Grape Ape Younger than Hack Tavern Member

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    Depends on whether you want it fixed or not. A good weld shop can wedl it regardless of the type of metal, even cast iron. The aluminum can be MIG or TIG welded along with stainless steel. Cast iron is heated and welded with special types of welding rod and it does a good job. Just look for a quality welding shop in your area, check with a few if until you find someone you are comfortable with.

    Then comes the new paint job. Welding will burn the paint off so keep in mind it will need painted to protect it.
     
  4. carptomm

    carptomm Guest

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    Do you think that a welding shop would take on the liability of welding a bike frame??
     
  5. Doc

    Doc Guest

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    I would highly doubt that any welding shop would take on that liability.
     
  6. vass

    vass Guest

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    frame is toast. there is no way to "re-weld" a busted frame and make it as strong as before. plus you lost alittle bit of the mat. from the busted part. you would have to add more steel,alum, iron to get it the same length/size.
     
  7. BigDumbBear

    BigDumbBear New Member

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    It's been 20 years now.... Let it go. The risk of running a re-welded frame is not worth it.
     
  8. tajcrews

    tajcrews New Member

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    Trash that thing and get something else. Not worth the cost of having the work done nor worth the risk of it breaking again. 20 years is a great run.
     
  9. gary spykman

    gary spykman New Member

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    The question isn't whether it can be fixed, it is whether it is cost effective to do so. I am assuming it is a lugged steel frame, being 20 years old. From your description it sounds like it is either the chainstay or the dropout which broke. A broken dropout is a relatively simple thing to replace, a chainstay is much more work. Then, as mentioned above, there is the paint. Unless it is a very high quality frame the repair/repaint work would cost more than a new frame.
     
  10. hewlett

    hewlett Guest

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    After 20 years, that thing is like your kid!
     
  11. Tarukai

    Tarukai SMILEY CAR

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    20 years is a very good run for a bike frame. As nice as it would be to repair it, after a run like that, let it go. A new frame would be the best thing, both in price and safety, plus now you have a large trophy for your years of riding to display. It can also act as a challenge for future bike frames to last as long :p
     
  12. BackBayBrewing

    BackBayBrewing New Member

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    I say fix it but that is only because I like to see people do stuff like this. If this is just a bike that you ride around town and not something that you are really pounding on, you should be able to fix it fine. Find a friend that is into welding, or even put up an add on craigslist looking for people with basic welding skills. If you wire brush the paint of the joint a good welder can put that thing back together.
     
  13. craisin

    craisin New Member

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    well to beef up the frame on my motored bike I am building, i cut a slightly bigger tube off another bike and cut it lengthwise so you end up with 2 half rounds that will fit around the existing tube.
    You can also drill hole thru the halves and weld it to the busted tube.

    if the tube is tapered you just use a section from where the taper is bigger

    For my project nothing has broken I just read in other forums where frames are likely to break and beef up that area.

    I get a friend to do the welding and he is less than half my weight and he is happy to put more weld on if I tell him

    If it breaks it was my call

    I had a RM 125 motorcross frame with a 50cc chinese honda clone motor registered as a moped and I wold ride it fast over rough private roads to see if it would break
    and weld it more if it did.
    most people I know weigh less than but they were scared to ride my bike:rolleyes:
     
  14. IanHighfield

    IanHighfield New Member

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    As pointed out by others, rewelding a frame is hit or miss. Try it but be prepared for failure or less than ideal result.

    One crazy way to emergency fix some frame failures in a product called Marine-Tex.
    This is a polymer (2 part) that has aluminum and silica particles mixed in it. It was formulated to fix boat engines at sea should they have a block or head leak. It can take temps up to 450 F. It sets up under water too. It's the duct tape of resins.

    Two years ago one of our riders snapped his seat frame tube free of the bottom bracket. Complete disconnect. All the other joining members stayed in place. He broke the bike in a practice jump up a short piece of 20% hill. (this was a hill climb race)

    No backup bike and the race was in 90 minutes. A mate dug out cans of Marine-Tex. Whipped up a gob and pasted it all in and around the broken tube and crank housing. Looked like a wasp's nest; all grey blob with branches sticking out of it. Branches being the bike tubes.

    Set up in about an hour. Hard to the touch. He had a go and the bike stayed together. He didn't win, but he didn't waste his time either. This man is strong enough to spin his tyres uphill on dry pavement. You can see him rack a rear triangle so strong is his effort. The poly-goo did the job.

    Needless to say, this is not a recommended practice.
     
  15. Industry_Hack

    Industry_Hack Total noob (& forum admin) Admin Staff Tavern Member

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    Cast iron?

    And what is wrong with you people, that no one asked for photos yet? Without seeing the actual damage, it's all conjecture. For what it's worth, the only frame I ever broke was on a Toyota 4WD. :eek:
     
  16. IanHighfield

    IanHighfield New Member

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    Mr. Hack: If I could sneak a good 4WD into our hill climbs, I can assure you I would. But I suspect the noise would give me away. That and the finish time. One hundred kilometers per hour straight up would turn heads for sure.

    As to frames: At any given British hill climb worthy of the name, you'll see frame damage of some kind in 20% of the entries. Cracks, bends, full breaks. Alloy is the worse offender. Carbon fibre is a miracle material and holds up best, better than my beloved steel even.

    We bend and break our rides because they are built to foolishly light standards. You would not ride a UK trial bike on the road for long. Especially if over 150 pounds. But this kind of building does expose weaknesses of design because we seek the ultimate limit of what's possible.
     
  17. HandsomeRyan

    HandsomeRyan ♥'s Bicycles

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    Buy a new frame (a new road frame can be had for $100) and transfer the parts from the rest of the old bike.
     
  18. TxCyclist

    TxCyclist Administrator Staff Member Admin Staff

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    Yea buy a new frame. If that portion broke there is a high probability that other stress points are near their end lives as well.
     
  19. craisin

    craisin New Member

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    You may as well buy a new bike after the drama of changing cables and other things that dont quite change easy:rolleyes:
     
  20. Georgewerr

    Georgewerr New Member

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    Hi Ian,

    You said that CF is a miracle material, your probley right but i'm to afraid of this stuff yet. I thought about CF for the bike I bought last year. I've heard of storys that they self implode. different type of bike though I bought a road bike that are made to be as light as possable and I'm 340#. They may be fine but I'm too scared

    George