My helmet size is Large.
I have several of those (open face) large helmets and all fit well from brand new.
I ordered a "Large" Z1R helmet and when it came I found that it was impossible to put it on my head Extremely tight!
I returned it and after a long, long time (wait) I was able to get an "Extra large".
This one was slightly better. I could barely put it around my head, but still quite tight.
I gave up. I got tired returning them and waiting for the next size up.
The helmet itself and padding is good quality, but the sizing is completely unrealistic!
I love the fit of this helmet. It does run large so I ordered what the measurements said I needed and it was too large. I Ordered the next size smaller and it fit perfect. I do wish the visor was larger. The small visor doesn't block any sun.
I've been needing and looking for several years for a plain, white helmet that is comfortable. I will admit that this helmet is quite comfortable. Even my husband said that it looked good, or "Cute!" were his actual words!
The two things that I don't like about this helmet is that the inner visor shield won't go over my prescription eyeglasses. Nada! My glasses are not large frames, either.
The other thing that I really don't like, and the picture does NOT show this, is the large (ugly!) Bell logo on the front. (If I wanted to advertise a helmet, it wouldn't have been a Bell model ...) Like I wrote above, I really wanted a PLAIN white helmet. So, this helmet does its job, but I feel jaded by the mis-advertisement, both with the visor and the front logo.
Finally found a helmet that my wife loves and will wear. It fits her correctly and she likes the look of it. The face shield is the part that she really likes since it can be pulled down to keep wind/rain off of her face.