Originally Posted by
TugaDude
.... Available for 30.9mm and 27.2mm seat posts....
So, it would seem not to be intended for use on frame tubes. Instead, you slip them over the seatpost, then install the seatpost. That's unlikely to be all that useful on most C&V bikes with level top tubes. I don't think there will be enough exposed seatpost to squeeze a bottle cage and bottle between the saddle and the seat stays.