Seatpost size?

[jomouk]

I have a Thorn Nomad, purchased in 2003 - Mark2??  I have been thinking about a suspension seatpost.  Not something I have paid much attention to previously, but I gather that the diameter could be either 27.0 or 27.2 mm.  Is that correct? Just 0.2mm difference? Nothing in my documentation indicates the size, and I doubt if I could measure it myself that accurately.  I fancy one from the USE range, or something similar, but am confused as to what size I should be looking for.

[mickeg]

Most seatposts are stamped with the size.  If yours is not, can you borrow a 27.2 seatpost from a friend that is labeled as such to see if it fits?  27.2 is a very common size.

You do not want to buy one that is 0.2 mm too small or too big, you want the exact one you need. 

A lot of bike shops have an accurate caliper, perhaps you could get someone to measure the seatpost that you have?

[macspud]

If it's a 2003 Nomad it would be a derailleur version (produced between 1996 and 2004). Production of the Raven Nomad Mk1 (Rohloff) as of 2007, If I  remember correctly the Raven Nomad Mk2 was released in 2010.
The seattube inner diameter will be 29.8mm so there will be a shim fitted. The shim should be labled for size?

[jomouk]

Thanks guys. I have managed to establish that it is 27.00 mm.

mickeg - useful advice! My LBS would have been my next stop. 

macspud - it was bought in March 2003, and is definitely derailleur.  I had been thinking it was Mk 2 simply because the brochure mentioned improvements that had been made, although it does not describe it as Mk 2.  But no, no shim, and not 29.8 mm.

[macspud]

Ah, sorry for any confusion, jomouk. Thorn Nomad Mk2 (Mk2 ahead stem rather than Mk1 quill stem) not Thorn Raven Nomad Mk2, though I thought I'd remembered reading that the derailleur model also had 29.8mm id seat tube. 
Glad you've managed to establish the seatpost size.