Originally Posted by
Andy_K
Have you seen this?
https://www.chapmancycles.com/cantilevers/
The accompanying essay makes my brain hurt a bit, but I find the interactive tool to be very illuminating. For center pull brakes, if I understand what it's telling me, the only thing you really have any control over is the length of the straddle cable/height of the yoke, and once you get beyond a certain point, which I think most centerpull straddle cables exceed, even that isn't a factor.
You are correct. It is a function of the angle between the two sides of the straddle cable. When the two sides of the straddle cable are at 90 degrees to each other, the force on each arm is equal to the force applied at the brake lever. If you have a shorter straddle cable, the force is multiplied and higher than the force from the brake lever. The closer the straddle cable is to being a straight line, the greater the force is multiplied.