Originally Posted by
Kontact
See, that's funny. You are propagating the myth that springs can't wear out when they clearly do. Systems with springs that are kept inside their elastic limit are fine, but small springs pushed too far do take a set and lose force. As almost anyone with a well used Shimano derailleur can tell you about their B springs.
The stiffness of the metal is the same. But yes if it's yielded (as opposed to actually broken) the geometry is different so the spring will behave a bit differently. But a B spring won't yield in normal use. You would need to overextend it somehow.