Originally Posted by
old's'cool
I suspect, though I don't know, that a reason they are not welded is due to the adverse effect of welding (due to temperature) on the material properties.
Yes exactly. Many aluminum things(rims, aircraft, etc) are/were not welded because the aluminum has to be re heat treated following the weld process or else the stresses can be unfavorable. Newer industrial advancements have allowed bike companies to be able to do such processes, therefore current rims are welded.