Replacing Mechanical Disk Brake cables I am having problems with replacing brake cables on rear wheel. The bicycle has mechanical disks. I removed old cable successfully and I've put the new one in. The thing is that I feel like it's not tight enough, but I cannot tighten it more. When I try using the brake, it doesn't brake at all. 

Here are the images:




I didn't cut the cable yet because first I'd like to get it working properly. Do you have any clues on what's wrong? I don't think that I need to adjust the brake, as I am only changing the cable.
The cable should be pulled through the pinch bolt on the brake, making sure any breaks in the housing are seated in housing stops on the frame, until it is tight enough that the arm on the brake is just beyond it's "relaxed" position.  Then tighten that bolt, check that it works, and if it does, leave about 3" of cable coming out of that bolt, trim the excess and install a cable end.  Otherwise, looks like you did a very good job installing a cable, for I'm assuming the first time?