Read about the technical (mechanical) differences of caliper brakes, disc brakes, V-brakes, and cantilever brakes. The latter two have long and short versions, while there are mechanical and hydraulic versions for discs.

It has to do with brake lever travel vs. amount of cable pull, and the mechanical advantage of the brake system as a whole. Getting it wrong will result in a spongy feel or a very stiff lever. Levers are matched to the brakes to provide the best performance.

You never indicated what model Sirrus you had. The discussion was focused on BB/crank, and not on the brakes.