Originally Posted by
C9H13N
The front derailleur in your picture is bottom pull and has a housing stop already.
Do you want to use a different bottom pull FD with no housing stop? You’ll need the Campy 626 pictured above. There is no cheap substitute.
well, yes
and no.
To split some hairs here,the Campy unit is the best and most commonly available, but there are others such as the Zeus, very much a Campy clone and Huret both of which will be harder to find and probably cost more than the already pricey Campy, if you did find them.
Also the clunky Simplex that has breakaway Delrin parts, not even worth looking for but probably could get for free if you found one.
You'd think that Shimano would have made thousands of these guides, yet I can't recall ever seeing one!
So the OP is correct that since he wants to use a bottom-pull FD with NO cable housing, the cheaper route is the plastic under BB shell bit, once you have a hole drilled. It doesn't HAVE to be tapped for threading since some of the guides snap into a plain hole...but I'd tap it.
The small problem you'll now have is this routes your RD cable to BELOW the chainstay, and the OP's frame has cable stop on the TOP of that stay. So if you don't want to braze one the simple fix is a clamp-on cable stop, and that doesn't have to be Campy or any pricey thing. In fact I have a small collection of mostly SunTour but a few other brands of these and can part with one for the cost of shipping but I bet any co-op has bins full of them.
These were generally intended to mount so the cable was on top of the chainstay, but nothing prevents them mounted "upside down" and I have done it dozens of times, works fine. Just have the machine screw above rather than below the stay.