this post was submitted on 03 Jun 2025
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My understanding is that in the factory, after welding, the entire frame is heat-treated to restore its strength and make the material properties uniform throughout. This is especially important for aluminum alloys, which lose significant strength in the heat-affected zone around the weld.
If you weld it again later, you're exposing that area to high temperatures without reapplying the same post-weld heat treatment which weakens the surrounding material. So while it’s technically possible to weld a cracked aluminum frame, the area around the weld will likely be much weaker unless you can re-heat-treat the whole frame.
This is a load of baloney. If it was welded before, it can be welded again. You only need to heat the effected zone not the whole frame. Also put a sleeve over top and add more weld. Heat treat isn't anything fancy. Get a temp gun and a propane torch. Get it to temp and let it cool slowly or quickly or both. depending on the spec you find.
The only reason they cook the whole frame is because it's easier from a manufacturing point of of view.
Sounds like a job for JB Weld.
I've considered it but I don't think it would last.
Preheat, expansion contraction control , and post heat is needed. But you wouldn't have to heat treat the entire frame, just this area/members of the weld. There are specialized welder dudes that you can probably find, but if its breaking from factory it will need extra gussetting. The pictures I saw the angled arm going up to seat post is more flat than vertical. Rather than bump force going up to the seat neck, it looks like it acts as a fulcrum and the bump would stretch the lower arm instead
This, if the factory can do it then a skilled craftsman can as well. Talk to some local fab shops, I'm sure you can find someone skilled in AL welding that can fix you up