So, I've ordered myself a NukeProof seatpost in a 27.2 with the intention of using a 27.2 – 30.9 shim. I want a plastic one so as to not rub off all the black ano like my old Thomson! Only problem is I've now realised they're out of stock in most places in that size (the only places left are gonna charge an extortionate ammount for postage).

Is it gonna be a huge issue to use a 27.2 – 30.0 shim? Can't imagine it's gonna make a whole lot of difference with 0.1mm added to the diameter (even if it does I could use wet/dry paper to reduce it slightly no?).

And the reason to not just buy a 30.9mm post?

Don't want half a silver post and half a black post from raising/lowering it against the alloy frame.

.9 off the diameter is actually quite a lot. Its almost a full mm out and you would have to be deforming your seat tube to get it tight.

It's not 0.9mm, it's 0.1mm which really isn't a lot.

Ah sorry I may have read your first post wrong. I thought you where looking for a 30.9mm shim but could only find a 30.0mm. If you have found a 30.8mm shim it may fit. Traditionally frame and seat post where worked in imperial and many American ones still are. The small variations are often just rounding out in the conversion to metric.

You could easily pack the space round it with plastic sheet of some kind.
Probably get a better fit too 😀

think he means he has found a 31mm shim and will sand down to 30.9mm

In stock at CRC

Even using a plastic shim, the ano will still start to rub off your seatpost if you're riding in mud, but whatever size you're after (I think one of your stated measurements is wrong in the first post) 0.1mm won't make much difference . . . if it's too tight then a plastic shim is a doddle to sand down a little, if it's too loose then a beer can shim superglued to the outside of your plastic shim would do the job (though would make it more than 0.1mm larger).

Dislclaimer: May well void your frame warranty . . . but I've been bodging shims for years 😉

I have a USE thermoplastic 27.2-30.9 in my spares bin that you you can have for £5 posted. Never used in anger and still in it's original box. Bought to try and get my Thudbuster 27.2 to work in my Rockhopper but the post still spins no matter how tight i do it up. Never ridden due to this although there are obviously a few light marks on the shim from insertion in my garage.

Email in profile if you want it.

http://www.evanscycles.com/products/use/shims-for-272mm-sx-posts–ec005387