hi there, when i first got my bike, the original brakes (magura hs33's) had been changed for a set of front and rear magura julie hydraulic disk brakes.i tried using the julies for a few rides, and found that the front one was an ideal brake for trials, and after watching some videos on the internet i noticed that the majority of trials riders were runnig some form of a disk brake on the front, and a magura rim brake on the rear.when i had a hydraulic disk on the rear, it seemed to slip quite regularly when i was up on the back wheel, putting a lot of weight on it and after a few weeks, i was out practicing kick hops and as my rear wheel landed, the brake slipped and i ended up coming off the back.that was when i decided to put a hs33 back on the rear! i hope this will be of some use when you are making your decision alex