A bad decaleur can ruin your bikes handling. My Custom Rando bike was a dream come true, with smooth and intuitive handling 99% of the time. But at higher speeds, it sort of buffeted randomly back and forth. At times it was frightening.

The decaleur was a Gilles Berthoud. They don’t make one of the correct length, so it was connected to the fabric rather than the leather part of the GB bag. It also attaches with a horizontal pin, which rotates and has some play in it.

I replaced it with a Compass decaleur, with 3” long spacers and bolts to drop it to the correct spot on the bag. The buffeting feeling went away completely. So I recommend keeping a good connection to the bars at the top of the bag.