Originally Posted by
DiTBho
28.6 mm seat post collars made of aluminium were common, now they are more difficult to find, but yes, you can see something on eBay and Amazon; I haven't seen a titanium one that size yet, and those in steel (Magristroni type) are for smaller diameters.
I'm seeing no shortage of aluminum 28.6 clamps on AliExpress:
https://www.aliexpress.us/w/wholesal...ost-clamp.html
There are several Ti fabricators in China who might make one for you.