Originally Posted by
TiHabanero
Why not simply bore the entrance/exit holes out enough to accept 5mm housing and run full length cable housing?
That's one possibility I'm considering. This method is basically "always available" as a fallback solution, if I screw up every alternative approach.
At this point I'm also considering:
1. Drilling a larger hole and inserting a plastic cable stop/cable guide as the one for Trek Boone I posted above.
This might look nice, but it might become problematic to find replacements once the current availability of such guides dries out.
2. Drilling a slightly larger hole and inserting (with a bit of interference fit) a step-down ferrule, like this Shimano one:
Aluminum Shift Outer cap with step | SHIMANO BIKE-EU .
Perhaps, also cross the cables inside the downtube to reduce ferrule wear. And even if the replacement becomes unavailable, it is not that difficult to manufacture such ferrules at home. Maybe even out of stainless steel.