I'm very new to mountain biking, and even newer to bike maintenance. Appreciate your time on a question that I'm sure is simple; I just can't find the right words to Google it.

I have a fairly nice Trek bike. The dropper post on it was losing pressure; I could add more and it'd lose it over a few hours or days. No one local wanted to service it, so I bought this for now:

Race Face Aeffect R Dropper Post (31.6/150mm)

I could probably have REI install it for a few bucks, but I'd like to take the opportunity to learn. Since there was a prior dropper post installed, it already has a cable & remote on the handlebar. I should just need to swap out the connection.

It was easy enough to disconnect, but now I'm looking at these two obviously incompatible interfaces and am totally lost (click for full size):

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In order: (1) New dropper post, (2) connection that used to go into old dropper post, (3) Included bead that looks like the cable goes through it, and fits into the hole on the new post.

Additionally, the new post came with an instruction sheet (available here). Steps 15 and 17 look relevant, I just don't have enough experience to understand what they actually mean.

Obviously, I need to remove the current assembly on the end of the cable, and put a new (simpler) assembly on it. Doesn't look too difficult. I just can't find any name of that connection to find the 10,000 YouTube how-tos I'm sure exist on it.

1 Answer 1


The aspect of the new post where the cable is secured is called the bottom cap assembly. The little black piece that holds the inner cable is called the cable bushing or, simply, cable holder.

You're going to have to remove the inner cable from both the old post's mechanism as well as the outer cable housing. It's important that the end of the inner cable is in near pristine condition in order for it to be fed through the new post's cable holder (picture 3) and then the outer housing starting at the seatpost end and up to the lever.

Generally I would use a new inner shift cable and shift housing in a situation like this. I would store the old cabling with the old seatpost if it appeared to be in good shape. However, I have bulk packages of inner shift cables and housing to work from. If you choose to use the old cabling, make sure there will be adequate length of both to connect the lever and new seatpost mechanism while having enough slack that the cable run doesn't interfere with turning the handle bars.

When the inner cable is routed thru the cable holder and outer housing, you'll place cable holder in its spot on the lower seatpost mechanism. It generally can only come in from one side which has a space for the inner cable to slide thru unobstructed. Next secure the ends of the outer housing with their ferrules in their respective places at the lever and lower seatpost mechanism. I will route the inner cable thru the lever body prior to setting the outer cable ferrule in place in the lever.

It gets a bit fiddly now as you continue to keep everything in place, pulling the extra cable toward the lever side as you install the seat post down the seat tube. You'll need to remove slack that comes with inserting the seatpost to depth. Keeping things taut will assist in keeping the ferrules in place while inner cable slack is pulled through the lever. Secure the inner cable at the lever's pinch bolt.

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