Macneil posted this on their blog yesterday—the aptly named Nub Post. The Pivotal wedge post taken to the extreme, it's a 50-gram trinket that allows you to only run your seat slammed and only after you cut off the top of your seattube.
Aw, isn't it cute? Sort of the little brother to the Stolen SIC post (will royalties have to flow both ways?) the Nub Post is roughly 30 grams—an ounce—lighter than the shortest available Pivotal post and a slim seatpost clamp. But that's not all! "Once you factor in the weight of steel mast and seat post clamp you have just removed….it actually does weigh….nothing." It weighs nothing! Sweet! And all you have to do is...wait, what?
Yes! Just decapitate your seattube! Don't mind the fact that it'll most likely void your warranty, or that you could easily cut into the weld. Let's ignore the fact that a lot of people don't even run brakes because it's too much of a hassle to install and adjust them or that most kids can't even cut the flanges off their grips properly. Just cut off the top of your frame! And hey, if you decide later that you want to run your seat higher, or that the wedge design doesn't hold well enough, well, just buy a new one. What's another $400?
Tell you what, Macneil: How about have people send their frames in, YOU cut off the tops of their seattubes, and if something cracks due to overtightening or compromised welds, YOU replace their frames, no matter who made them. How does that sound?
Look, I understand that it looks a hell of a lot better than zip-tying or hose-clamping a seat to the toptube. And if you're willing to cut the top off your seattube just to be able to run your seat a tiny bit lower and save a whole two ounces, I'm not gonna try and stop you. But it begs the question: What is light enough? We'd already gone from this to this to this. What's next? Are we not men?
Also, it seems to me that seat tubes are designed to take pressure one way (an external clamp tightened down around a solid seatpost) and now you're asking them to accept it another way (an internal wedge pressing outwards) right where a bunch of welds meet. Throw in thin-gauge tubing and kids with hacksaws, and you've got a recipe for disaster. And I can't wait for the rash of cracked and split seat tubes when people inevitably run this thing without cutting anything at all.
Oh yes, and from what I heard (and read in the comments), there was initially a shot at this blog in the writeup. What did it say?