How to choose the correct dropper post.

Author: Andrew Schneider   Date Posted:23 April 2017 


It wasn't long ago that were all riding fully rigid posts and had to stop at the top of each descent to lower our posts.  The introduction of dropper posts has been in my opinion, one of the best mountain bike inventions to date.  A dropper post will transform your ride and allow you gain more confidence on the descent.  It doesn't matter what type of bike you're on.  A dropper post is something I simply can't go without!

You may have noticed all the different sizes and versions available.  So, how do you know you have one that's compatible with your frame?  We'll help you identify compatible posts by giving you tips on what to look for.  

Things you need to determine:

  1. Seatpost diameter. 
  2. Internal or external routeing.
  3. The amount of drop.

1. Seatpost diameter.  Common sizes are 27.2, 30.9 and 31.6.  The easiest way to determine what size your frame needs is to look at the bottom of your existing post.  The specs are usually printed at the end, if not, your owners manual is a good place to check.  Also, you may hear of people using shims to make smaller posts fit frames.  Please avoid this, it's not worth the hassle and potential issues that could/will arise.  

 Example of specs printed on seat post.  If this came out of your frame, you will need a 30.9 post.

2. Internally vs. external routeing.  New frames are increasing coming with internal routeing for a clean look.  If you have an external routed frame, unfortunately, internal routeing will not work.

3.  The amount of drop is extremely important if you are running a smaller sized frame or have a shorter seat post height.  The commonly available drops are 100, 125, 150, and 170mm.  There are some brands that have sizes in between, but generally, you're going to have something between 100 and 170mm.  At correct seat height on smaller frames, you'll most likely be unable to fit 150 and 170mm length droppers.  If you can, it may be indicative that your frame may be too small.  If you're concerned about fit, an easy way you can determine fit is to measure your exposed seat height from the top of the seat tube to the seat rails.  Remember that you still need to add a few centimetres the accommodate for the seat post collar. 

We hope this guide will help steer you in the right direction for choosing a new dropper post.  As always, we are here to answer any further questions and will do our best to find the perfect product for you!

Until next time, 

Andrew Schneider.


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