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Is a cracked aluminium frame trash?

cavangohcavangoh Posts: 2
edited November 2017 in MTB general
I recently cracked my 7 year old polygon aluminium Hardtail, it was a great bike, but does it mean that it can't be ridden anymore?

Posts

  • cooldadcooldad Posts: 32,601
    Aluminium can be welded by a pro.
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  • cooldad wrote:
    Aluminium can be welded by a pro.

    It is still very difficult and expensive. Get a quote and find out if it’s a cost effective fix. Probably not worth it with Alu.
  • RockmonkeySCRockmonkeySC Posts: 15,247
    cooldad wrote:
    Aluminium can be welded by a pro.

    It can but the heat affected zone is very brittle leaving the frame quite a bit weaker than before and it obviously wasn't strong enough before if it broke.
  • fudgeyfudgey Posts: 859
    No one has asked yet where the crack is...

    Any pics?

    You guys obviously dont know any decent welders....
    My winter bike is exactly the same as my summer bike,,, but dirty...
  • fudgey wrote:
    No one has asked yet where the crack is...

    Any pics?

    You guys obviously dont know any decent welders....

    Best welder in the world can’t repair damaged aluminium that easily. It’s not like welding steel. Heat effects it’s properties and leave it brittlecas mentioned. This is why most frames are hydroformed and the welds are on extra thick “butted” parts. A crack on a thin sidewall is pretty much terminal. This is where carbon can be easier to repair than metal.
  • RockmonkeySCRockmonkeySC Posts: 15,247
    I used to be a welder. Doesn't matter where it is on the frame, it will be weaker after welding.
    Aluminium frames are heat treated after manufacturing to relieve stresses and also temper the aluminium. Welding it after that heat treatment reintroduces stress due to heat distortion and also makes the parent metal around the weld more brittle.
  • 02GF7402GF74 Posts: 1,294
    some Al alloys used for bike frames need sophisticated heat treating whereas other don't - many Al frames have been welded up successfully, sometimes with additional bracing.

    so you need to decide how much the frame is worth and how much it would cost to weld whether to go ahead, and depending on where it has failed, whether additional bracing is required.
  • Unless the frame is a particularly rare version or has sentimental value, I doubt any Alu frame is worth the cost of a repair. And even then there is no guarantee it will not break again in the future. And if that happens when you’re halfway down a hill you’ll certainly know about it.
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