Originally Posted by Deanster04
When you bend aluminum you will initiate stress risers and eventually the frame will crack. No telling when. You can probably ride it safely but eventually it will fail sooner than an unstressed bike. When you bend it out it will not cold set like steel. Good luck.
While what you are saying it true at the limit, a tiny bend in an alum structure (2mm over a 60cm distance) is unlikely to be significant. A nice property of alum is that it is malleable and alum structures are built all the time which are formed into shape by bending aluminum - for example airliners. I'm sure the bending does cause some ultimate reduction in fatigue strength but unless a crack was formed and unless the material is repeatedly bent to deformation, I doubt the reduction in frame life is significant.
As a further example, people crash their alum frame bikes all the time and I'm sure they tweak them now and then by small amounts. If what you were saying is true, any alum frame bike that has been crashed either needs to put on a factory jig and seen if the alignment changed or immediately thrown away.
I do agree that you don't want to attempt to bend it back like a steel frame.
But I'm not a framebuilder or a metallurgist; this is just a common sense approach to the issue.