The dropper post sags when seated
That soft sag when you sit down almost always comes from the hydropneumatic part, not the cable or the collar. On posts with a chargeable air valve (Reverb type) it's usually loss of pressure or the valve; sometimes it's recovered by recharging/bleeding according to the brand. On sealed cartridges (OneUp/PNW type) it's seal wear: you replace the cartridge, you don't repair it —and it isn't the same as replacing the entire post—. Note: it isn't the same as it not going up (that's usually collar or cable) nor as side play (bushings).
Telling the exact symptom apart saves you money: the vertical sag and the "won't go up" have different causes.
What the symptom is telling you
Elastic sag when you sit down. The post yields a few centimeters, like a soft spring, and returns when you stand up. That's air/oil: either the air chamber lost pressure, or the internal cartridge seals let it through. It's not the cable.
Depending on the type of post. If yours has an accessible air valve (Reverb family), the brand's recharge or bleed procedure may restore the feel. If it's a sealed cartridge (OneUp, PNW and many modern ones), the usual route is to replace the whole cartridge: it's the part designed for that, much cheaper than a new post.
Key facts
Tell us the model and we'll tell you whether it's a rechargeable valve or a sealed cartridge, and what's needed. Message us on WhatsApp
Frequently asked questions
Why does it sag when I sit down?
Almost always the hydropneumatic part: pressure/valve (Reverb type) or cartridge seals (OneUp/PNW).
Is it fixed or replaced?
On an air valve it can sometimes be recovered by recharging/bleeding; on a sealed cartridge you replace the cartridge, not the whole post.
Is it the same as side play?
No: the sag is vertical (hydropneumatic); side play is from the bushings.
Related
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