Mathew Caulfield asked whether or not I put a hard crease in my
bellows when I fold them: I certainly do.  The reason is simple: When
you leave the crease wide, the wear and tear will be concentrated in
that section of the cloth and the bellows will wear out more rapidly.
If you put a sharp crease there, it's like a pair of pants-- when you
bend your knee, you still have the crease, because it didn't move very
much, so the rest of the pant leg had to do the moving so you could
bend your knee.  That means, you "strain-relieved" the area that the
wear is normally concentrated in.  You are forcing the cloth to
distribute the wear and tear equally on both sides of that crease.

   Now if you leave a peak fold to "travel" back and forth, or you put
in a flat fold (I never recommend that for anything) which causes the
inside peak on the sides to strip the cloth as it moves, either way,
you will wear out the cloth MORE RAPIDLY with a sharp crease than with
no crease at all.

Craig B.