Re: Frame Reinforcement Issue
I think theses frame crack because the steel is not flexible. Earlier steel frames were heavier, but made from a mild steel with more elasticity.
To fix your frame, you could attach your reinforcements in such a way that they form a second set of chain stays. Mount them halfway between the seat stays and chain stays.
I would use steel instead of aluminum. It is much easier to weld.
In the long run, I would find a used frame from the 90s or older on craigslist or something.
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