I’ve just bought a 2nd hand Reverb dropper post.

At full extension, locked, the saddle moves up and down – like a suspension seatpost. I’ve never even tried on before so I need to know; Is that normal or does it need some fixing?

Thanks…

its not normal. it needs a full service. its got air where it shouldn’t have air. I hope you got it really cheap…

Not right should be solid when you sit down usually some rotation movement try a bleed and check pressure.

When you fitted it did you bleed it afterwards?

If it’s not a stealth bleeding should not be required.

Post should not sag.

Mine had similar – there is a small white bit inside that breaks, causing this. A full service will sort it.

PS – Ive just bought a new one for £188 from BikeDiscount.de

It was cheap – £40

So I’ll get it serviced – Thanks guys

Air has migrated past the IFP, really common, especially if you ever pick the bike up by the saddle with the post down, hang it on a rail with the seat down etc.
Service will sort it easily enough. Any decent LBS should be able to sort it.