Quick Question: How do I Fix a Slow Dropper Post or One That Won’t Stay Up?

With this Quick Question series we will present fast fixes and collect comments from seasoned riders around specific D.I.Y. mountain bike repairs. While much of this trailside triage is covered in our repair articles and videos, this is a space for longtime riders and readers in the Singletracks community to share their knowledge. Please type your related experiences and advice in the comments below. Do you have a quick question? 🤔 Email [email protected]

Worldwide, trail-o-philes agree that dropper posts have played an important part to improve riding and mountain bike design. In our 2019 survey asking readers to choose the most important component on their bikes, 794 of the 3,470 respondents checked the saddle up-downer, making it the most popular component by a long shot. Hydraulic and spring-actuated posts these days often function without a hitch, provided they receive a bi-annual cleaning and some fresh grease.

When posts do perform poorly, there are a few quick things to check before ordering a new cartridge or pedaling to the bike shop. If your post is returning to full-mast slowly, the first place to check is the air pressure. Unless it’s a coil-actuated post, there is often a Schrader valve under the saddle clamps that can be inflated. Check the manufacturer’s maximum inflation recommendations and pump accordingly. A lot of posts will take up to 300psi, but it’s best to peek at the online manual to be sure. Also, check that the seat post clamp isn’t too tight, as an overtightened clamp bolt will prevent the dropper from returning at full speed.

If the air pressure is topped off, and things remain sluggish, it’s likely time for a service. Most posts can be torn down and cleaned at home with tools you already own, and they will return to full velocity with less grit and some new grease. While you’re in there, it’s likely worth changing the seals and possibly replacing the brass keys (if applicable) that keep the saddle aiming forward, as they wear down and allow the post to wiggle and wobble over time.

Photo: Matt Miller

If instead the dropper won’t stay up, and it’s sliding up and down under applied pressure, there is a good chance the remote cable housing is kinked at the base of the dropper, preventing the cable from retracting to the locked position. This can happen if you push the post into the frame without simultaneously sliding the housing along with it, or if the housing gets shoved into the seat tube without the post moving up in tandem. With movement on one side and blockage on the other, the housing bends and slows or seizes the cable inside. This happens often on demo bikes that frequently have their saddle height shifted, and it’s also a regular occurrence for riders with shorter legs who have to fight the balance between inserting their post deep enough for proper saddle height and the housing or actuator encountering interference inside the frame.

The repair for this issue can go a few ways. If the cable is clamped at the post, as it is in the photo above, you might be able to slide the cable out of the housing a few centimeters, cut the damaged housing, and gently reattach the cable to the knarp. That’s the lucky case. Often, the frayed cable end makes reattachment impossible, so you will need to feed a new cable through from the lever.

If your cable is clamped at the lever, as most modern versions are, you might get away with sliding the cable completely out of the housing, chopping off the busted bit, and sliding it back in. Again, the fray can make this tricky. In either case you may finish with a dropper housing that’s too short to properly turn the handlebars, and you’ll need to replace the housing entirely. Fortunately that’s a quick fix with most modern frames, and the fresh lines will often make the post work like new.

Your turn! Have you experienced and dropper post woes and found quick fixes for them? Please share those tips in the comments below.

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