Originally Posted by
striknein
You're absolutely right. That said, it's a lot easier (and safer) to turn a 24.0mm seatpost than it is to turn a larger one. That seatpost does fit my '82 UO-9.
I'm glad you found one that fit your UO9. I've looked for something to fit on my UO-8 with little success. I'll have to measure it again and see what it is - it's a bizarre number.