i got the initial adapther with the pack n pedal bag and use it on my non thule rack. Unfortunately, it is made of very low quality plastic. When i tighten the screw to secure the bracket, the plastic pat on the nut breaks.
Since i have already invested on the expensive bag, i went ahead and bought a replacement. Bad move...
The second piece was worse. Taking the leson from the first mistake, i was very careful to not to overtighten it. But it never seem to be able to be secured properly to the rack. After a week, i tried to tighten it. The screw seem to have siezed. I put some lube and left is for some time. It seem to work to loosen the screw but again the plastic around the screw nut broke again..
I would definitely not recommend this and since it is the adapter that allows the thule bag to be attached to non thule rack, it will be big factor to consider.