Has anyone here used the plain seatpost + clamp + Brompton 'saddle adaptor pin assembly' .(404). How has that worked for you? It looks like the cheapest way out..
I have.. plain seat post is 7/8" the tube of the SAP is same .
Mine is now on my winter bike, [I had a Mk2 Brompton, shorter top tube, I used it there, sold Mk2 and bought a Mk 4 Bike (longer TT) , so it migrated.]
JRA.. I wouldn't do jump on the saddle CX or single track on it..