Query on internal routing of brake cable/outers

avsd

Veteran
Location
Belfast
I am building a new bike which has internal routing. I can thread the cable outer through the frame for the back brake in a single run. From the brake level to the brake. The frame also has the option of terminating/stop the cable outer at the front of the top tube and then run a short length of cable outer from the rear of the top tube to brake itself. Which is the better option? Thanks.
 

Cycleops

Legendary Member
Location
Accra, Ghana
A pic might be useful.
 

Ian H

I am an ancient randonneur, & I often stop for tea
Location
East Devon
Less outer cable is more efficient, but the difference for brakes is likely to be marginal. Gears are a different matter.
 

Sittingduck

Legendary Member
Location
Somewhere flat
I can only think of one advantage to running the outer sheeth inside the TT, that is for ease of cable routing, e.g. if feeding an inner cable only is tricky to exit the hole at the back end of the TT. If that's do-able I would not have an outer needlessly inside the tube. Presumably you have 2 different options of fixture available to you that secure into the tube and anchor the ferrules? If not I don't really see how it would be possible to have the outer sheeth running continuously through without there being a gaping holes. I probably didn't explain that very well but maybe you get the jist...?
 

figbat

Slippery scientist
I have frames with both setups.

The one where the outer terminates outside the frame is a bit tricky to change cable inners (not impossible but tricky).

The one with a continuous run of outer has so far been no issue, but some complain of cable slap on the inside of the frame - there are options available to prevent it.

I wouldn’t even think about the frictional differences - there are pros and cons either way and given a choice I would probably go for a continuous run of outer.
 
OP
avsd

avsd

Veteran
Location
Belfast
Some photos:




604560


604561


A few photos as suggested. Thanks for the response. It is a Planet X frame I got resprayed. There is an fitting that screws over a large hole in the frame. I think cable replacement will not be a big issue when that time comes. Thanks for the response on friction of cable - that was one of my concerns and it is clear that it is not a major issue. The fitments would need to be drilled out to allow the cable outer to enter and exit frame not a problem but a 'road of no return'. My remaining concern is the pull on the outer cable if I make sharp right-hand turns. I suspect for this reason I will go with two short cable outer runs and leave the brake cable uncovered in the frame
.
 

si_c

Guru
Location
Wirral
Personally I'd run the outer to the stops, just to prevent any rattle of the outer against the frame itself. I doubt there are any efficiency advantages either way.

To run the inner, take a full length of outer, and feed it along the current inner until it pokes out at the front, then run the inner through and remove the outer. Once you've removed the inner cable it can be a bit of a faff trying to get it to poke out sometimes, you can use a magnet to help though.
 
OP
avsd

avsd

Veteran
Location
Belfast
Magnet and bent paperclip sorted the inner cable run. Stopped the outer cables at entrance to frame. :okay:
 
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