Originally Posted by
Schwinnsta
Buy a cheap seatpost quick release clamp for a few dollars to fit your diameter seatpost. File off the protruding part and place it on your seatpost so that the seat post cannot slide down.
Here is a picture. Zoom in on base of seatpost.
++1
Brompton seat should stay Dry apply nothing..
My Cure also,
a 2nd QR seat post Band clamp, (a De Lipped 31.8)
directly around the seat post it self... To Fold bike completely,
I just open both QR levers..
on mine they both lay on top of each other, folded back..
...
On my Bike Friday Pocket Llama I have a 27.2 band it's one of these.
online found picture
...