Grand Prix 250
Main Motorcycle: 2017 Thruxton 1200R
Join Date: Aug 2018
Location: UK Midlands
Other Motorcycle: 1998 Honda Hornet CB600
An old post - but I will add my experience for anyone else that miht find it.
I use a Givi mobile phone holder - from memory a S957B. It came with a rain pouch, but in my experience I have never needed to use it; the zip type is water resistant with a seal on top of the teeth. I rode in torrential rain as recently as last Friday and the phone was bone dry on removal. In any case, the phone is waterproof if the Givi case ever did leak.
A nice bonus that I found after purchase is that my QI inductive charger plate easily fits inside so I don't have the faff of plugging the phone USB socket in to the charging cable; I just place the phone on top of the plate, and zip up the case. This brings a secondary bonus in that the USB plug is well inside the case - not poking out of the bottom collecting water droplets.