Uhc performance carbon fibre the b12 combines one of our most aerodynamic frames made from felt uhc performance carbon fibre with race worthy components for a sacrifice free performance shimano dura ace derailleurs are paired with microshift 11 speed shifters for a seamless transition between gears felt ttr3 wheels shave weight while offering superior aerodynamics for a bike that works hard to get you to t2 shimano dura ace derailleurs dura ace is shimanorsquos top of the range groupset and