Originally Posted by
SJX426
Not sure I understand your question. The difference to me is that the liner has a lot more lubricity properties than a steel cable on a steel surface. As the cable starts a groove, the contact surface area increases with a corresponding resistance or drag, coefficient of friction kinda thing. The liner is probably better than when the cable was cutting through the paint!
It is worth checking every once in a great while for the cable cutting through the liner. I don't know what the service life is of either cable liner shown.
The grooves are part of the design, they are not caused by the cable travelling a cm every now and then. In my experience the better bikes had grooves cut into the BB shell and the cheaper used a plastic mold attached to the bottom of the shell.
If the grooved guideway wasn't better why is it used on more expensive bikes?