different head fits different helmet.
Fren wanted a branded helmet. Tried on the L size Shoei, took it
off immediatedly cos its squeezed him and gave him a immediate
headache wearing it.
Tried a Arai and felt comfortable with it.
Because of the shape, the weights and the cushioning of the
helmets, you really can't find one that fits all.
Certain full face also have a certain curvature of the visors that
can distort your vision if you are relatively short sighted or has
astimatisim (My spelling wrong, no time to correct today. Will edit
another day.)
Like my 1st MHR helmet, put it on, look thru the visor and I
immediately swoon.
Took me some time to re adjust to the helmet, and I avoided looking
left or right w/o turning my head cos the visor is distorted, your
judgment of near or far is different in the begining of wearing
one.
