cute helmet & I like the optional visor. I'm a 56cm, so I went with a medium. Sadly too big, and the adjustment in the back didn't 'close' as much as it looked like it could have (still had about a cm to go, but the straps prevented it from squeezing closed any further) .
ps. For those who might care-- on the 'gloss white bomber', the stripe is greener than it appears-- more sea foam green than aqua blue.