i have a late 70s Minoura mount with a Salsa stainless cage attached (replacing a vintage Jim Blackburn aluminum model I sadly vibrated to death last year) on the '78 Competition GS. It just works. Never yet spit out a bottle, even on a dirt road ride. I intend to do every vintage event I can while using it. There is a little change in the handling when it's full, but not enough to matter for me yet.