Airflow Helmet Questions

[1967 R50/2]

This question is really for the Non-US crowd. I live in the US, but I'd like to pick up an Airflow helmet, and there are probably a number of ways to do that, but they involve me generally not being there in person.

So my question is regarding sizing. Not being there in person means I have to get the sizing correct without the benefit of trying it on. I am usually a medium. My head measurement is 57.5 CM

Now wouldn't you know it, BMW sizing goes from 56-57 and then from 58-59.

So where am I in this equation? If you have personal experience with the helmet, please chime in.

Also if you know a good source that ships, let me know.

[BMW Atlanta]

As far as sizing goes, visit a dealer that carries Schuberth Helmets. They are the manufacturer of the BMW helmets sold everywhere but the US. That should give you a good indication as to the fit and size you require.

[1967 R50/2]

Already did that. The sizing in cm for the concept helmets is actually different. No range is given. To further confuse things, if you convert the english measurements on the SchuberthUSA website they come up different than the given metric measurements: For example: A medium is 56cm (stated as 57). Large is 58cm (stated as 59).