Here is the Phone Mount i made for my motorcycle. This holder is a exact fit for a Samsung 9+ with a Spigen Case Thin Fit (https://www.spigen.com/products/galaxy-s9-plus-case-thin-fit?variant=570798145537) The phone slides in from one side and has a cover with a screw tightening it down.

The bar diameter on this bike is 22.5 mm I used some (good) double sided tape to make sure it is tight and does not tilt during driving.

Mount bolts: All bolts are M4 (Hornback PLU-nr 12122)

Cover Tightening screw: I used the bolt of a GoPro with the GoPro Knut to tighten the cover down. But you can also buy a few on AliExpress using this search string: "SOONSUN 3 pcs/lot Black Aluminum thumb Knob Bolt Nut Screw set for GoPro Hero 4 3+ 3 SJCAM For Xiaomi Yi Action Camera Accessory"

Charging cable: This is a cheap cable of AliExpress and has a 90 degrees angle. Glue the holder part on the case when the phone is in. In this way can allign the connector perfecly. Get the cable by searching on AliExpress using this string: "PZOZ USB Type C 90 Degree Fast Charging usb c cable Type-c 3.1 data Cord Charger usb-c For Samsung S8 S9 Note 9 8 Xiaomi mi8 mi6"

DO NOT use PLA for this print as it is not as strong and cannot handle heat and has the tandancy to start deforming