Framebuilders - Seatpost + Bottle mount dilemma

Due to smaller frame size, my seatpost is stopped by the top insert of the bottle mount and not going further down. My Thudbuster just came in today and it's even longer:notamused:

How do I go about removing the threaded insert from the frame? It looks like it's been stamped/pressed on both sides, like a rivet. Thanks.

205093
205095

With the seatpost off and looking down the tube, I see this:
205094

I'd cut the seatpost to fit. Leave it as long as possible. Measure thrice, cut once.

Yeah, I thought about pulling out the hacksaw but I want to know my options. My first precious add-on and I have to chop it up. Lol

you didn't say what kind of frame it is. Many frames have pressed in inserts and you might as well remove them if you can't live with the part inside the frame. If it's steel, it probably will work without the inside part.

I have cut down a seatpost on my lathe, I see no reason to have a seatpost that is that long down inside a frame just waiting to get stuck.

It's an aluminum frame. I got it removed now by hammering in an Allen wrench and pop it off.

Sounds like your issue is resolved?

The item in second pic in your first post is called a rivnut and the best way to remove them is using a drill bit the same size as the hole in which the rivnut is secured. Drill deep enough that the head of the rivnut comes off and then push the remaing bit back into the hole. Turn your bike upside down to get it out of the seat tube.

FWIW , different in that its steel, Bike Friday adds the waterbottle brazeons
to the surface , behind the seat tube, uses a different piece,
the external is the hourglass piece, that often gets used for rack mounts,
brazed to the side of tubes,
but to the desired effect,
no interference in the seat post coming down.