How to Choose A Dropper Post

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Let me guess, you came to our website to buy a dropper post, but with eight different options, two types of routing, multiple diameters, and recommendations base on the type of bike, you wound up scratching your head in confusion? We understand where you’re coming from. The selection process can be confusing no matter how many times you’ve bought a dropper, and that’s why we’re here to walk you through the decision making journey. Read on to see which dropper post we would recommend based on your, and your bike’s, needs.

What A Bike Wants, What A Bike Needs

Choosing a dropper post isn’t entirely based on personal preference. Your bike actually has more sway in the matter than you would initially expect. Things like cable routing capability, seat post diameter, and overall post length all need to be addressed before you can start making decisions based on your “wants”. So let’s take care of your bike’s needs first.

Internal Vs. External Routing

One of the first things to do before purchasing a dropper post is to determine whether your bike is compatible with internal or external cable routing. By this we mean whether the cable for your dropper post can be routed inside your bike’s frame, through a series of built-in channels and holes, or if it must be attached to the outside of the frame with straps or zip ties. The routing capability of your bike does not impact the performance of your dropper post, but it will affect which dropper posts work with your bike.

Our Rainier, Bachelor, and Ridge Dropper Posts are only compatible with bikes that are built for internal cable routing. The actuators of the aforementioned dropper posts are located on the bottom of the dropper and will be inside the frame once the post is in the seat tube.

How To Choose A Dropper Post With PNW Components

Our Cascade and Pine droppers are designed for external routing. The actuator is located by the posts’ midcap and will be outside of the bike’s frame when the post is inserted in the seat tube. The Coast Dropper Post is unique in that there are two versions: one compatible with internal routing and one compatible with external routing.

How To Choose A Dropper Post With PNW Components

Post Diameter

The diameter of your current seat post will also determine what dropper post can fit your bike. Four seat post diameters are commonly used in the world of cycling: 27.2mm, 30.9mm, 31.6mm, and 34.9mm. There are two ways we recommend to determine which diameter dropper post will fit your bike. The first is to check your current seat post to see if the diameter is stamped on the bottom of the post. Your second option is to look on your frame manufacturer’s website for the seat tube diameter. 

How to Choose A Dropper Post with PNW Components

These diameters are largely determined by your frame manufacturer and by the type of riding you are doing. 27.2mm seat posts are common in hardtail/XC/gravel/cyclocross bikes, while 30.9mm/31.6mm/34.9mm seat posts are usually on mountain bikes. If you happen to purchase a dropper post that is too small in diameter for your bike, you can use a shim to get it to fit properly. However, if you purchase a dropper post that is too big in diameter, it’s physically impossible for it to fit your bike and it will need to be exchanged.

Travel/Overall Post Length

Our dropper posts range in travel lengths from 90 to 200mm. When we say “travel length” we’re referring to the maximum distance that the seat can raise or lower when the post is actuated. For mountain biking, we recommend using a longer travel dropper post like the Bachelor, Rainier, or Cascade to get the seat out of the way while you’re descending. Doing so not only increases safety but gives you more clearance for getting sendy.

How to Choose A Dropper Post with PNW Components

If you’re looking to purchase a dropper post for a road/gravel/CX bike, we recommend looking into a shorter travel dropper post like the Pine, Rainier 27.2, or Coast. The overall length of a dropper post is directly tied to the travel length (i.e. longer travel = a longer overall post). Since these types of bikes often have obstructions in the seat tube that will hinder dropper post insertion or high standover heights relative to modern MTB's, it’s likely that your bike will only be compatible with a shorter dropper post. Use the instructions and dropper post calculator below to determine what length of dropper post is right for you.

How to Choose A Dropper Post with PNW Components

Determining Correct Travel Length

Recommendations aside, dropper post length is based off of a combination of personal preference and what your bike can handle. Be sure to use the following steps to measure your current seat post and find the correct dropper size for you and your bike. 

Step 1: With the seat post at full height for pedaling, measure (in millimeters) from the top of your seat collar to the center of your saddle rails. This is called maximum extension. 

Step 2: Measure from the top of the seat collar down to anything in the frame’s seat tube that would stop the dropper post from inserting further into the frame. Examples being water bottle bosses that protrude into the tubing or a bend in the seat tube for suspension linkage. This is called maximum insertion. 

Step 3: Combine maximum extension with maximum insertion to find maximum total length. Do not purchase a dropper post that exceeds this length as you will not be able to adjust it to a proper fit. 

You can also input these measurements into our dropper post calculator located on our dropper product pages to see our calculated size recommendation.

Now It Gets Personal

Okay, now that we’ve covered the absolute necessities and have taken care of your bike, let’s make sure you get what you want too. Read on to learn about some of our posts’ nifty bonus features.

Adjustability/Fine-Tuning the Perfect Fit

If you’re a hands-on person and enjoy fine-tuning your bike, then a dropper post designed with a customizable feature may be what you’re looking for.

Our Bachelor Dropper Post is designed with a tunable air cartridge that allows the rider to make changes to the dropper’s rate of return. Add more air to the cartridge and your seat will rise faster, eliminating wait time at the start of a climb.

The 3rd Gen. Rainier comes with a new tool-less travel adjust system that enables riders to reduce their dropper’s travel up to 30mm in increments of 5mm. If you are in-between sizes and struggling to find the perfect seat height, the new Rainier gives you an easy way to eliminate this issue.

Or, if you’re looking for a height adjust dropper post for your commute or gravel bike, the Coast Dropper Post’s 40mm of tunable air suspension may pique your interest. The suspension alleviates large bumps and impacts, making for a smoother ride while you tackle forest roads or potholed commutes in a seated position.

How to Choose A Dropper Post with PNW Components

Price

Our dropper posts are continually some of the best-priced on the market. We hate how expensive bike parts are and we’re leveraging our industry relationships and in-house sales team to bring you affordable products. Our dropper posts range from $129 (Cascade and Ridge) to $239 (Bachelor) and come backed with exceptional customer service and a three-year warranty.

Let's Sum It Up

Let’s sum things up and help you narrow down your choices, shall we?

We’ll start with dropper posts that are best suited for gravel or road bikes. If you’re looking to upgrade a gravel bike and want a little extra cushion to enhance your comfort, check out our Coast Dropper Post. Is saving weight on your road bike a priority and you need an externally routed post? The Pine could be perfect for you. If your road/gravel bike is compatible with internally routed posts and you want the lightest dropper possible, the Rainier 27.2 is the way to go. 

Now for the mountain bikers’ dropper posts. If you’re looking to wet your toes in the world of dropper posts and want something effective and extremely affordable, the Ridge Dropper Post might be your best option. If your bike needs an externally routed dropper, you’ll want the ever-reliable Cascade Dropper. Want to fine-tune your fit and maximize your travel with the latest tech? Our 3rd Gen. Rainier and its tool-less travel adjust system will help you be as comfortable as possible on the climbs. Last but not least, if you want to treat your bike to affordable luxury with an internally routed dropper that has a tunable air cartridge, we highly recommend you check out our Bachelor Dropper Post.

As always, if you have further questions please feel free to reach out to our Customer Service team at info@pnwcomponents.com. They'll get you sorted and back on your bike in no time.

 

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