Seatpost sizing

Hello,

I need some help sizing a seatpost for my new build (Simoncini track frame).

Now, I have measured the diameter or the seatpost tube and it is 22mm. This seemed a little small as I cant find a seatpost this narrow so I though I must be doing something wrong. I took the seatpost off my other bike 27.2mm and as I suspected, it was too wide. However, when I measured the diameter of the other bike, it was not 27.2, more like 24. So my question is, where did this 27.2mm size come from. Is it something they made up, do I need to apply some maths to this? I am stuck please help!

Also, I have looked on the sizing charts on the Sheldon site and my frame is not on there

Cheers

Mike

How are you measuring? Calipers of some sort are really the only way.

+

or ideally

I'm just using a ruler! I understand calipers would be needed for .1mm etc, but its the difference by about 3mm which threw me.

You would be surprised how easy it is to miss measure with a rule, I've tried before and end up with a diffrent number every time.. Most bike shops have some calpiers so you could take the frame there or buy some for cheap from machine mart or maplins.

Cheers. Can you believe that the guy gave me a ruler which was measuring in some unknown system. Not in cms or inches. What the fuck. I have remeasured with a normal ruler. And it is exactly 27mm. If 27.2 is too big, then I guess it must be exactly 27.0

Unbelievable. His ruler was measuring in units of 1/500 of a foot. I mean, what the hell is the point of that? so 27mm was according to this ruler 22, but that is 22/500 of a feet if anyone is interested. Man!

Ahhh. Prob some old machinist's ruler for parts which don't require 1000s of an inch accuracy. Imperial measurements are strange They start to divide up units interms of a base 2 type system but then once they get down to about 32th or 64th of an inch it starts to go all decimal instead, weird there is prob a good reason behind it / point of history. Anyway you're right why the fuck would you give that to someone to measure a seatpost

mike take the frame to your lbs and get them to try out different seatposts in it til they find the right one. they should have some old ones lying around. once you have the measurement then either buy from them or ebay, whatever. that's what i do anyway

A bike shop should have a actual seat tube sizing tool. They are like ring sizing tools.

A bike shop should have a actual seat tube sizing tool. They are like ring sizing tools.

^^^ What I was gonna say...

Cool. Thanks for the help. I will take it to BLB later for some moodiness off the bird who works there