Dropper post on a folder?
 

Toying with this concept at present, but not finding much out there online.

Tern/Dahon seat posts are 33.9mm external diameter, 27.2mm internal diameter, right? The Tern telescopic post’s upper section has a 27.2mm external diameter. So a 27.2mm dropper post should fit inside the top of a standard post then. Externally routed cable should be possible from there, following the rear brake and gear cable route to the handlebars. Anything missing from this so far?

Some cargo bikes have a dropper so short people can reach the ground at a stop.

Mainly why I’m considering it for the town Tern ridden mainly by my partner, rather than for some xtreme gnar off-road on my drop bar wannabe bike packing Tern. Of course, it seems that Tern’s cargo bikes use a slightly different diameter seat tube compared with the folding Link and Verge series, so I can’t closely copy anybody who’s done that change on a GSD or HSD.

I can confirm your dimensions. I used the Tern telescopic post to add in a 27.2 Thudbuster on my Swift.

At least the wider seat posts (generally) have a longer travel.

i used a dropper with saddle lever when riding with kids shot gun (between me and handle bar). It was good as i could lower it as I approached a set of traffic lights or junction… and it was strong enough to attach a trail gator (tag along)… so on kid in shot gun and the other being pulled.

but i cannot understand why you want one on a folding bike even if you share it as you always adjust the saddle post height and droppers are about 1.5kg making the bike heavier.

Googling "27.2 dropper post" results in many available products. If the reason for purchase is to quickly change the seat height for different riders, then the posts with the dropper lever located directly under the seat would be a very clean solution.

Running all the extra cabling and cluttering up the cockpit for a remote dropper lever is really not needed unless you plan on making adjustments when road conditions don't allow safe removal of one hand off the handlebars to grab the lever under the seat.

Which would normally be the "xtreme gnar off-road" situations stated above which isn't a planned activity anyway.