Very cool design! I have had some good and bad experiences with those single-bolt clamping designs. I bet it has to do with the tolerances of the cones.
One of the weirdest bike designs I have ever come across is BMC’s angle lock seatpost on the 2011 team machine SLR01.
It uses a cam, coupled to a turnbuckle, connected to an elastomer on the bottom of the seat tube
Funny story how I came across this design: I found a teammachine frameset behind a dumpster at my velodrome. I ended up building it up and riding it for a bit . The seat post creaked a lot
I actually think the design of the seatpost quill was pretty cool, but they were just trying to do too many things at once for no reason.
The first 26” I built for myself had a pretty janky 27.2 wedge post. Pivotal seat posts are pretty easy to convert since the bolt is through the top of the saddle.
Beatifull work and nice pictures. What are differencies between internal stub post style and external in terms of usability and performace? Thanks for opinions.
Majority of builders using external style. I am building now road bike with ISP with ST with OD 30.4 mm and ID 27.2…it allows to me cut ST and use normal seatpost in future. I am planing to use external Ritchey Seat Mast Topper 30.4 ID.
I’m totally in on this! I’ve always wanted to do an ISP but have heard to be cautious doing one in steel. Spooked me a little bit. Why would doing an ISP in steel be sketchy? Using too thin material for the ISP?
I guess it could buckle if you use a too thin of a tube? I would prefer to have a tube buckle than snap in half like carbon does, but it’s also true that those carbon tubes are made on purpose for this while the steel are not so maybe the “danger” comes from this?
the “maybe ill chop it off later” choice is 30.4? What tube would this be?
I am curious because the seatpost and seat tube are the main driver of vertical compliance in a road/gravel bike. 30.4 and 34.9 steel tubes are going to be much stiffer than a 27.2 carbon seatpost.
I believe the scare comes from using too thin walled tubing. I think it needs it to be a thicker walled tube for strength but that also comes at a price with weight.
Those of you that have built with steel ISP’s, what walled tubing did you use?
@Daniel_Y I have filament wound carbon tube with 27.2 ID and 30.4 OD. It looks very stiff. I think it may works for my 75kg:). I am planing it to use it on my personal build.
I bought tubes from m.carbo. He is selling from Poland (EU) as I am EU based too.
Underline note. Thanks for this forum, there are many educated people and people with right questions. I am a hobbyist with limited time for errors:), so right information really helps me.
I used a 28.6 tube with a 0.8 wall and made a spine for it to ensure the buckling doesn’t happen. See photos up further. It has workd nicely over 20000km of ridning between both bikes. I would say I probably won’t build another one. I think a nice 27.2 carbon post gives a really nice ride and no complications.
This is still on my todo list. At some point when I have some time, I will curate all great projects and information on the site into a few posts and locations. Americans call it “Spring Cleaning” which I never do
Agreed. I think ISP is mostly for aesthetics, and I can’t argue with that!
I think the funniest example is Caley Fretz’s ISP coupler mosaic:
Cool discussion!
I’m considering trying to do my first design for printed metal, and the part is either going to be an ISP topper or a weld-on topper for a 27,2 or 31,6 mm tube seat tube.
I’ve seen different brands including the Enve 2-bolt hardware in their design, and I’ve also heard that it’s more reliable than the single-bolt version. Do any of you have any experience with the Enve 2-bolt hardware?
I’ve also tried to look for drawings, specs, or dimensions requirements, but I can’t find any… Does anybody have some information or knowledge about compatibility?
. The seat post creaked a lot
