Joined: Jan 2010
Posts: 9,813
Likes: 1,790
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Also, let's not forget that welding aluminum causes significant distortion in the tubing after the weld has cooled, not to mention the related residual tension stress which further greatly weakens the structure. Only re-heat-treating will cure the loss of strength and stress-relieve the welded region.
LarDasse has it right, JB Weld won't fix the crack.