Mechanical gear cable routing options

[foz]

I am undecided on cable routing options for a possible new frame... I like the simplicity of "traditional" exposed inner cables along the DT and chainstay, and even the possibility of heat lever bosses and not just cable stops, so that I can use DT levers if I want
But I do like the look of internal cables, and while I plan on mechanical gears and rim brakes, I just wonder if I might need or want to go electric at some point in the future, in which case exterior cable bosses would be redundant and look a bit out of place, so maybe fully internal cabling would be a better idea? That would not let me use DT levers, but really I don't think I'd want to, I just like the idea of having options... But while a lot of frames have cable entry ports into the DT, and either out at the bottom or even out of the chainstay before the dropout, I wonder if these might be a cause for frame failure? Anything in particular to look out for with these, regarding location, size, etc.? Anyone had issues?

 

[zerogravitas]

What kind of bike is it to be? All weather tourer? Or sunny days best roadie?
If the latter I would definitely go for a semi-internal routing, not total through the headset nonsense, but just enough to clean up the lines. If it's going to get wet/muddy regularly then stick to external.
Obviously any time you create holes in a frame you are making ways for moisture and crap to get in!

 

[bikeworkshop]

We see loads of modern frames failed at the cable/hose entry point, and old ones too.

You have to accept that if you have a structural tube and then drill a hole in it, you deffo haven't made it stronger

But as well as a stress riser, you've also added an ingress point for muck and corrosive crap.

If you think you might go electronic in the future, why not think of going wireless - that will become normal.

Tidy hydro routing options under the toptube is what i do - and exposed cable inners along the frame tubes allows easier maintenance and lower friction.

I have worked on over 10,000 (well used) bikes by now, so my sample size is big-ish.

Internal routing gives a clean look though, if that's important to you.

 

[foz]

I am leaning towards a titanium frame, plus it's dry here and I haven't ridden in the rain for years, so not worried about corrosion! I do like the clean look, and the option of going electronic without leaving unused bosses on the frame, no plans for that but the way things are heading there might be no choice in a few years... But then again, same thing for rim brakes I suppose, if I'm sticking with them then why not just assume I'll have no trouble with parts for mechanical gears either?

 

[bikeworkshop]

External fittings have had a standard for a very long time, so are likely to be available well into the future.

Wires for gear shifting could easily be run through the breather holes within the frame if they are well positioned and wide enough.

I've seen a few ti frames broken on cable/hose entry holes.
Most recent was a ribble.

Rim brake kit above a certain quality point is already getting challenging. Disk brakes allow a replaceable braking surface so if you want straightforward maintenance and future compatibility, the braking system will be more of a sticking point than the frame routing details!

 

[wynne]

I've thought about this a lot.
Even in pretty much the worst slop I prefer the function of exposed gear and brake cables run externally. Obviously, there is a bit of cable outer at the lever and derailleur ends but overall it gives a very clean look without the hassle and potential weakening of the frame of internal routing.

When I had my Chickens cross frame made I specced it for cable disc only, such that a naked brake cable runs from the stop near the head tube to the stop on the seatstay next to the disc mount. It functions well, is easy to maintain and looks really clean.