# dropper post cable +housing



## mack_turtle (Jan 6, 2009)

it seems like common practice is to use a shifter cable and housing to actuate a dropper post. any reason I should not use a brake cable housing and a shifter cable instead? compressionless brake housing? brake cable and brake housing?

I ask because, in spite of using brand new Shimano housing and a slick Shimano cable, my actuation is _rough_. I wish it was smoother. I've dripped Triflow in the housing and it's still rough. no tight kinks, the lever moves freely and smoothly, the actuator on the post moves fine, but somewhere between the lever, smooth curve to the downtube, external routing under the DT to a hole in the seat tube with smooth curve, it still feels like poo.

(KS Southpaw lever, new Shimano housing and cable, smooth curves, PNW Bachelor post all on a Karate Monkey)


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## SqueakyWheel73 (Sep 21, 2018)

mack_turtle said:


> it seems like common practice is to use a shifter cable and housing to actuate a dropper post. any reason I should not use a brake cable housing and a shifter cable instead? compressionless brake housing? brake cable and brake housing?
> 
> I ask because, in spite of using brand new Shimano housing and a slick Shimano cable, my actuation is _rough_. I wish it was smoother. I've dripped Triflow in the housing and it's still rough. no tight kinks, the lever moves freely and smoothly, the actuator on the post moves fine, but somewhere between the lever, smooth curve to the downtube, external routing under the DT to a hole in the seat tube with smooth curve, it still feels like poo.
> 
> (KS Southpaw lever, new Shimano housing and cable, smooth curves, PNW Bachelor post all on a Karate Monkey)


It seems like the obvious question is if the brake cable housing would fit in both the thumb shifter and where the housing terminates at the bottom of the dropper seatpost - I'm thinking about the wider diameter of the brake housing. If you have internal cable routing, the larger housing also has to fit into the opening in the frame. I'm not sure this would work with mine.

As I recall the brake cable is also a slightly larger diameter than a shifter cable, so this also means you would have a little bit of room inside the housing - would that matter?

Sounds like an interesting experiment


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## SqueakyWheel73 (Sep 21, 2018)

mack_turtle said:


> KS Southpaw lever, new Shimano housing and cable, smooth curves, PNW Bachelor post all on a Karate Monkey


On a somewhat related note, I just serviced my PNW Bachelor post and it does not feel as good as it did before I worked on it. I have to take it apart and check it again. Just wondering if there might be another cause of the problems that you are experiencing...


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## J.B. Weld (Aug 13, 2012)

I can't see how brake housing could help, shift cables & housing are designed to be ultra-smooth for precise shifting. If the cable is good there must be something else responsible for the excess friction.

It's debatable whether or not lubing cables helps but if you do you need to pull the whole cable out of the housing, dripping lube down the housing won't get far.


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## mack_turtle (Jan 6, 2009)

I don't know if the bends in the housing are enough to make a difference, but in my BMX days, we used linear brake cable housing (aka compressionless) because your brakes would lock up if you did a full barspin or a tailwhip and the housing got wrapped around the head tube. standard brake housing binds up if it's wound up too tight, which could cause enough friction on a dropper post if bent too tight. I also used standard brake housing on a front brake fed through my fork steerer. linear housing was too stiff to work in that application.

the inner diameter of brake housing is almost certainly quite a bit larger than shift housing.


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## J.B. Weld (Aug 13, 2012)

mack_turtle said:


> the inner diameter of brake housing is almost certainly quite a bit larger than shift housing.


A sloppy fit doesn't mean it will be smoother. I've set up a lot of droppers using std. shift cable & housing without issue so I kind of doubt that's causing your problem.


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## rx4mtb (Jul 20, 2012)

It should be simple enough to slide another cable through the housings and feel if/where it’s binding. Check the one you pull out for any barbs or fraying.


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