Will wearing a helmet hurt my dreads? - Dreadlocks FAQ's

No, it will squish them a bit and they will look funny for a while but they will be fine after a little palm rolling. When your dreads are tighter they won't get squished as much but it will be pretty hard to get a helmet on your head. You'll have to find an extra large helmet.  If you know you are going to be wearing a helmet you should probably avoid putting beads in your dreads, at least higher up, so they don't get squished into your head. Just a thought : )