I'm buying another bike and it comes with a Joplin seatpost 30.9 that requires servicing. I've never used one of these and tbh, cant see me using this one. So what is it worth? I would be willing to swap for a 400mm nice seatpost.
Under the seat lever i believe. Not really had a look at it yet, but will post some pics up when i get it. It will need to be sold or swapped, cos it will never get used by me!
