I have Tubus Duo front racks on my VWR Patagonia. The bottom tubing is 14mm and the standard lower hook on my Classic Rollers does not in anyway fit over the tubes. I believe it is setup for 10mm tubes. I put a number of small washers on the bolt which allows me to tighten the hook reasonably well over the tube however when you remove the pannier the hook becomes floppy. I found these
from ortlieb but they are for QL1 systems. By chance does anyone know if they fit the newer QL2 QL2.1 systems?
https://www.ortlieb.com/en/e110/
Bear