Originally Posted by
rmfnla
This is where your argument falls apart.
If the elastic cord or foam pad reach the end of their elasticity and the transmit all additional force to the object being listed then yes, no force is lost.
In a brake caliper, once the arm starts to flex additional force makes it flex more, so the effort is going to deflecting the arm rather than to pushing the pad to the rim...
Deflecting against the rim, force against the rim.
We can get lost in the details, but boiling it down it's really just movement of the brake handle per movement of the brake pads. Coefficient of friction, hand force and we're done. Factor in some Hooke's Law stuff if you want to, it probably does make a difference using longer calipers, running out of handle pull.