sic_nick":31wwyn0u said:You are going to need something akin to what you said in your original post that fixes to the brake pivot like the Brake Therapy ones:-
http://2btherapy.com/bikes/brake-therapy-conversion-kit
Although to be honest you don't need to have a rear disc other than symmetry, I have a couple of bikes that I can't put a rear disc on but as 95% of my braking involves the front wheel it is not an issue (I weigh in at 100Kg so there is a lot of mass to slow down too). I only use the rear brake to bring the back end round in corners when I need to and a good set of V's is more than up to the task.