TREK FX 4 CARBON FRAME SIZE XL LOCATION OLAYA The FX Sport Carbon 4 is a carbon fibre fitness bike for fast-paced, lightweight road bikes with more comfort and handlebar control at the same time. This bike includes an ISO Speed decoupler that smooths out rough roads and the 1x11 drivetrain and simplifies shifting without sacrificing a gear set. These features make a professional, high-performance bike perfect for many uses, such as individual training and group rides.