What brand and model are you talking about?
Figure your circumference
and then find the correct helmet.
All my helmets are Giro Eclipse with Roc Loc 3. It keeps the helmet securely on my head.
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.