I've got a rather big head (I know, I know) and I am delighted with my
special order size 8 Tilley outdoors hat (25 1/8"; 64.5 cm).
I am getting into WW open canoeing and when I did a course none of the
helmets on offer fit me and it was agony to have to wear an L/XL one.
Pete, my head also falls outside the scales of most helmet manufacturers,
Well, that explains a lot.
--Chris