How to Install a Dropper Post | TranzX

How to install a dropper post on a fatbike

Seatposts are probably one of the least flashy parts on your fatbike, yet they play such and important role.  I have ridden with stock alloy, aftermarket alloy (bling), suspension post (Thudbuster) and carbon (Wren).  All of which have certain advantages and characteristics.  The one seatpost that did not get under me was a dropper post.


Several of my buddies have dropper posts and swear by them especially when riding into technical downhill sections.  I would stop and manually drop my post as they flip a lever and keep on riding.  Putting the seat back up in riding position is actually more of a pain.

When the Norco Ithaqua 2S landed I had the opportunity to try a dropper post as it came stock on the blue carbon beast.  The dropper was a TranzX 125mm air actuated with a bar mounted cable remote . . . I just had to install it.  How hard could it be?

The 8.5 x 11 one fold instruction sheet appeared pretty complete as I quickly skimmed the words and glanced at the pictures (mistake number one - read everything twice).



How to install a dropper post TranzX Instructions Sheet

The first step involved sliding the cable through the lever mechanism with the fixed barrel resting inside.  I then mounted the lever to the left side of the bar, just inside the grip.

TranzX on a Norco Ithaqua 2S

Secondly, the cable had to be fished through the housing.  In my case the housing was already run inside the frame using the GIZMO internal cable routing system and out through the seat tube.

TranzX dropper post install

After accomplishing that, I needed to trim the end of the cable to the specified length and install a removable barrel end.  Not having the proper cable cutter I improvised with a set of linesman pliers.  It wasn't the neatest job, but it worked.


The barrel end securely seated itself in the bottom of the dropper post and the post was secured in the frame.  Easy peazy . . . or so I though until I looked back up at the bar.


Now I'm no expert in installing dropper seat posts, but that large unnatural curve sorta looked wrong.



I then took the time to read the instructions (twice).  No real help there on explaining the steps to correctly measure and cut the cable.  Calling up some extra brain cells I figured out a way to address the issue.


Step One - Get the Correct Tools

I could have used the linesman pliers again to cut the housing and cable, but I wanted to ensure a clean cut so it was off to my LBS to secure a cable cutting tool.

Using a EVO cable cutter

Step Two - Remove Seatpost

This will allow the housing/cable to be pulled through the frame giving the perfect curve up at the bars.

Ithaqua 2

Step Three - Measure the Housing/Cable

With the perfect curve, mark the housing where it enters the frame.  I used a piece of green tape. 


Reinstall the seatpost and pull the housing/cable back towards the bar to make that large unnatural curve. 


Measure the distance between the green tape and the frame . . . and that is how much housing needs to be cut off.  In my case it was 9.25".


Step Four - Prepare for Cutting


Remove the green tape from the housing.  Take the seatpost out of the frame.  Remove the lever from the bar and pull housing/cable out through seat tube. 


This left a significant amount of housing/cable sticking out of the seat tube.  Remove the cable from the bottom of the seatpost, trim the cable flush with the housing and measure and mark 9.25".  I used green tape again.  


Step Five - Cut the Housing

You only get one shot at this.  Before cutting the housing be sure to pull the actual cable back through the housing so when you cut the housing you are not cutting the cable as well.  Then push the cable back through the housing.


Trim the cable as per the measurements in the instructions and reinstall the barrel.


Connect the barrel to the bottom of the seatpost, as per the instructions, and reinstall the seatpost, pulling the slack housing/cable out through the front of the frame.


Reinstall the lever on the bar and admire the perfect curve.


It was a little bit of a nail biter when making that final housing cut, but it all worked out. (whew)

If your dropper post cable runs outside the frame it will probably be a little easier to install as you will have full access to the cable.  The hidden internally run cable made the process a little more complicated . . . but its not impossible.

Ride Fat !

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