Seat post clamp size ?

[cyberknight]

For a carrera virtuoso .
27.mm seat post and i only have a normal tape measure so i cannot get accurate enough to measure if i need a 31.8 or 30 etc etc .
Went over a big bump on the way to work and the clamp thread split so i had to cycle rest of the way to work with the seat flopping about , the seat post rack clamp held the height .
Used a jubilee clip and cable ties to hold it all steady for the homeward trip , i do have a QR clamp but for some reason the rack is not as tight with that .

 

[goody]

I've got a Vanquish and think they are the same. The battery in my calipers is dead but I put them on the seat tube of the Vanquish and on my MTB which I know is 31.8 and would say a 31.8 would be the right one.

 

[cyberknight]

I've got a Vanquish and think they are the same. The battery in my calipers is dead but I put them on the seat tube of the Vanquish and on my MTB which I know is 31.8 and would say a 31.8 would be the right one.

Cheers i thought it was but i just needed a double check, the rest of my bikes have over sized seat posts so they were no help .

 

[02GF74]

wrap a piece of paper round the seat tube where the clamp would fit - make a mark ont the paper where it overlaps, using a ruler measure the distance between the two marks and divide by 3.142

 

[goody]

MMMmmmmm 3.142.

 

[Catweasel]

MMMmmmmm 3.142.

You're rounding it up - it's gonna be bad pie.