Bodge-Jobs You've Done.

[monkeyseemonkeydo]

Will get some sorted. It basically uses a cheap automotive gas strut to provide the upward motion and the seatpost clamp to lock and unlock the system. The seatpost has a groove milled into it with a corresponding sprung loaded, ball ended bolt sticking through from the clamp to keep everything straight. Also used a 25.4 post so that I could use a USE plastic shim as a bush for the post to pass through so as to stop metal-metal contact. Works rather well (and weighs about the same as a 'proper' dropper) even if I do say so myself!

[bike_dummie]

Sound interesting, defiantly gonna give this a go once our milling machine is up and running!

[monkeyseemonkeydo]

Right, here we go. First up pics in the lowered and raised positions:

The components: The gas strut had to be turned down by a fraction to clear the ID of the seatpost and I just used a couple of bits of delrin to act as a spacer to the top of the seatpost and a stop which sits on top of the main pivot tube inside the seat tube. It's set up so that at max extension the post sits at the perfect height so it always goes to the right place and I can then lower the post to anywhere up to 150mm when I feel like it. A little bit fiddly to operate the QR on the move to start with but now pretty slick at it and since a lot of dropper posts operate via a lever under the nose of the saddle I didn't think it was too bad.

Close up of the ball ended screw that goes through the seat clamp and seat tube:

The travel:

The only mod needed to the frame:

Will add a vid of it working when it finishes uploading.

Edit: Hopefully a video...