I'm a newby in the matters of bike mechanics but I recently decided to build my own mtb.

Now that I'm in the end (I think) of this painful process I'm facing a irritating problem. I can't insert the front derailleur internal cable. The hole seems obstructed because I feel something soft in the end of the cable at half way.

Can it be the rubber cable inside the frame? If yes maybe it's curled or out of position...

Any tips?

Thank you.