Seat post size/Vernier confusion :-/

Well an OD of 35.1 is close enough for a 34.9mm mech. Is the seat tube OD still that much at the seat clamp end? Or is it externally butted at the BB for reinforcement?

If you really want to check your sanity just measure it by eye with a ruler to see if you are in the right ball park. Or get all accurate and measure the circumference with some string and divide it by 3.14.
 
if you want exact measurements , you need a micrometer

vernier`s are close enough , or as they were called in my last job "verynears"
 
Try using them to measure something you know the diameter of, like another seatpost or the quill of a stem. The accuracy of the calipers may not be perfect, but then again the diameter of something may not exactly be as quoted either.

+/- 0.2mm for a seatpost shouldn't really make much differance. I could squeeze a 27.2mm post in my 27.0 Zasker without worrying too much.
 
Tallpaul":2j12ja8o said:
Try using them to measure something you know the diameter of, like another seatpost or the quill of a stem.

I'm in the early stages of the 'hoarding disease' you lot have probably had for years so I ain't got any spare parts laying around (yet :roll: ), thanks for the tip about butted seat tube at BB end, makes sense....will check when I next go back to work....

BUT I could check the Cannondale I just bought.....what sized seatpost should that have? (M1000 3.0 series)
 
We have a pair a seat post sizing rods that are graduated in .2mm increments. Just drop one in the frame until it stops and read the size. It is tough to do with calipers since, as you mentioned, most of the opening aren't perfectly round.
 
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