Remember too that helmets come in 2 different shapes, round and oval. It makes a big difference in how they fit.

I was down at my buddy's bike shop when a lady brought in her 15 year old son to get a dirt bike helmet. Chuck gave him the biggest one he had and it would not fit. We nicknamed the kid 'Punkinhead'.

Wanna run my Goat heads-up sometime? It's a 5.7 too. Should be a good race.