Under BB cable guides
I've been thinking lately on routing cables on a frame of mine.
There is a cable guide right next to the rear derailleur. The frame uses old style shifters mounted to the frame.
To connect the rear shifter with the derailleur, I would need to run under the bottom bracket.
There is a hole at the bottom of the BB, but its diameter is 7-8mm. Now, is there a guide I could actually mount to such a huge hole? It is not threaded, and I am not even sure whether it should be actually used to mount a cable guide.
What I should be looking for? There are dozens of plastic under BB guides, but they all come with a small-diameter mount. Any phrases I should search amazon / ebay against?