Originally Posted by
am8117
Sorry, but I could no help this one. Reading of STI 5600 / R700 manual (disclaimer notes):
https://si.shimano.com/pdfs/si/SI-6KD0C-002-ENG.pdf
"Use a [sic] frame with internal cable routing is strongly discouraged as it has tendencies to impair the SIS shifting function due to its high cable resistance."
Since, Shimano moved on to the concealed cable housing for not only brakes but also shifting and introduced the right angle kink to the shifting cable right in the lever, also there's no mention on the internal cable routing at all (4700-9000):
https://si.shimano.com/pdfs/dm/DM-ST0002-05-ENG.pdf
So, what has changed since? Are the cable housings space tech now?
Newer 10 (Tiagra 4700) and 11-speed shifters pull more cable per gear shift, compared to the 5600 / 5700 10-speed shifters.
This provides a bit greater margin for error, making the system a bit less sensitive to any cable and housing imperfections.
Not that I'm a fan of internally routed cables - quite the contrary.