My bicycle is a Rockrider 520. I have replaced my front derailleur with Shimano Acera FD-M390 and my crankset with Shimano Acera FC-M391. But chain is rubbing inside of FD even when FD cable is not attached. I tried completely loose L screw but it still rubbing and FD is not moving inside anymore. FD is parallel with chainrings and there is 3 mm gap with FD and biggest chainring. How can I solve this?