having a large "noggin" should not affect your hat wearing abilities at all because if you did not know, they make different sixe helmats. <small secret that very little people know.
seriously though. go to your shop with your helmat and try on different hats under your helmat you fuck. and if that doesnt work then take out the padding in your hemlate to make more room for the hat. ohh... and use common sense before you make a thread.