Brian Reay was thinking very hard :
I don't think the outer compresses much. It is a spiral wrap so it is
flexible but, as it bends, the spiral turns are in contact. I doubt the metal
will compress much. The 'gap' between the turns on the outer of the bend may
close a bit as the device is operated- typically you see the outer move a
bit. As you say, the inner is under tension.

I agree, the outer doesn't compress much, but they come under
compression when the lever or what ever is operated.