Yup the classic disadvantage of round bars but do not wish to replace. No matter how much I tighten everything either the saddles rotate or bars rotate when loading a 50 pound kayak. Beyond the obvious tighten more or replace are there any home made remedies or mechanical makeshift customizations to solve this?
I never really solved it completely
Hence I use Thule. But a partial solution is to wrap an abrasive material around the bar such as a piece of window screen where saddles or whatever are attached. That increases the force needed to make the bars or the attachment turn but did not eliminate it completely for me. YMMV.
that’s like trying to put
a square peg in a round hole
Epoxy putty
I have a friend that used two part epoxy putty (the stiff kind like play dough) and made a triangle wedge on top of his bar that fit the center triangle in the Thule carrier on the bottom of the j rack. It seems to be working for him so far.
I find the rotation helpful
The saddles I use, Malone, rotate with the hull of the boat. They tilt to the rear when I start loading, then follow the rocker of the boat as it moves forward. The rear one ends up tilted a bit to the front, for example, when it is at the first rear bulkhead.
Tighten very carefully
You could “crush” the bar via over tightening
severely affecting its geometric shape
and hence weaken its strength capabilities.
Once it gets a kink, dent, etc. its ruined.