On the frame it has a sticker 30.9, but on-line literature shows 31.6....maybe they changed to 30.9 on recent frames ?
Jet9 RDO is 31.6
Rip9 RDO is 30.9
I don't think they have changed it.
I have a 6 Berth camper van that I rent out . It is based in Tauranga, New Zealand
I guess I better check with Niner prior to ordering seat post, 'cause it is the Jet9 rdo and sticker says "use only a 30.9 mm seat post in this frame"
Just called them and they confirmed wrong sticker was applied, so still 31.6. Thanks