Why no housing on straight derailleur cable runs?
In this age of premium coated cables and hydro brake lines, how come most frames run derailleur cables unhoused on straight runs (e.g. along the seat stay, seat tube, top tube, etc.)? Seems like you would get better long term performance with fully housed cables, especially in muddy conditions.
Just wonderin ...
less friction, less weight
Tradition/weight saving/quality of housing in the past for the most part I suppose. I run full housing on a few bikes and it's just better especially in adverse conditions. Less friction for the full housing runs IME as there's not multiple entry/exits from the housing and not as easily contaminated as with interrupted runs.
"...the people get the government they deserve..."
There's the matter of weight savings, but mostly it's a matter of style.
Years ago in the days of steel road bikes, gear cables were generally run bare, but many builder wouldn't use braze-on fulcrums for brake cables, believing it weakened the frame. On the other hand, the clips holding the housing used to slip around, and lot's of have cut our legs on the screws.
Bare wires make for a nice clean look, and eliminate the problem of the cables sliding around. It's almost impossible to keep a 2 foot unsupported housing in place,
so you'd need extra clips to do the job.
The key to solving any problem is to understand and address the underlying cause.