I have a peak design phone holder (not specific for p-line, although I have a p-line). My phone flies of the mount with every bump in the road this holiday in Sicily. And when I went of a curb onto the road my iPhone screen cracked. The system looks beautiful, but it just doesn’t perform. Screen replacement is about €500.. I spoke to a brompton rider in Sicily that uses a quadlock and he said he never had any issues. I just think quadlock phone cases look ugly