Mine actually broke off last week. I have a gift certificate somewhere to a cycle shop. So till i find it...i'm riding with sunglasses and clear glasses till I find it.

Anywhooo

I was going bout 60 with my glasses on...shield up....and it slammed shut (scared the $hit out of me) and every time after that it would slam shut...then i turned my head once going 55 and bye bye face shield..( just bought it too)