Next time, put 2 big washers on the sides of the BB shell and the same on the head tube. Fix them with a threaded rods and ordinairy nuts.
Cut the washers free with a hobby knife after painting to prevent that larger pieces of powdercoat will chip off.
By the way, Decathlon is not that bad.
I can imagine that they have HP and BB tools, even for milling, facing and chasing threads.
Next time, put 2 big washers on the sides of the BB shell and the same on the head tube. Fix them with a threaded rods and ordinairy nuts.
Cut the washers free with a hobby knife after painting to prevent that larger pieces of powdercoat will chip off.
By the way, Decathlon is not that bad.
I can imagine that they have HP and BB tools, even for milling, facing and chasing threads.