I am looking at a full suspension MTB with an Aluminium frame. It's cheap but needs to be welded as the frame is cracked. The bike is a Cult Insomnia 52 inch. It's cracked at the lower bracket, is it scrap or worth a repair?

1 Answer 1


Presumably that's 52 cm. Generally, a crack in an Al frame (or most frames), especially in an area which gets a lot of stress makes it scrap (esp. if its supposed to be used off road).

Given this, I'd scrap this frame.

  • 1
    To add: The strength in Aluminium alloys is dependent upon its heat treating, they usually add something like Magnesium to create precipitates in the alloy which make it strong. If you know someone who knows how to weld Aluminium they should know how to deal with this and it shouldn't be a problem otherwise it's risky.
    – Pigeon
    Apr 10, 2015 at 11:17
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    An overlap piece could be (professionally) welded over the rewelded crack, to improve its strength. With a little care, it might be possible to make it look inconspicuous. Main concern is the heat treatment during welding, and also the material at those welding places might not have the same properties as at the places of the factory welds. I doubt you wanna pay that bill unless the bike has a special meaning to you. Technically possible, practically quite a headache.
    – Sam
    Apr 10, 2015 at 15:51

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