What are peoples experinces/thoughts on this?

Im wanting a Carbon 30.0x400mm post, although not really having much luck, so thinking about a 27.2, and using a shim.

However, something worries me about using a shim with a carbon post, especially as its nearly a 3mm gap.

Any help much appreciated.

Lego

Its only 1.5 mm each side. I’d use a plastic one rather than a ali one.

I was thinking that, but still wasnt sure, mainly as it will be run towards the upper limit.

If it makes any diffence, Im thinking of getting the Pro XCR Post.

used a Post Moderne shim from wiggle to shim a 27.2 EC70 into a 30.9 frame. a lip or burr on the inside of the top edge of the shim put a groove in the seatpost on its first ride. 😯 🙁

either get a plastic shim, or make sure you sand down all the internal edges on the shim. Had I paid full price for the post (and not 25 quid from jensonusa 8) I’d be livid, as it is I’m just a bit p1ssed off.

No reason it shouldn’t work. But shims are a pita if you move your seatpost much.

I’d never use a shim, but then i’d never be bothered about a carbon post.

Check out the U.S.E site, they make plastic shims for carbon seatposts.

I had a shim on a stumpjumper using a USE Alien carbon. Never moved the post up/down and was fine with it. Think the shim would have been from 27.2 to 30.9 (but could be wrong, was a few years ago).

Yeah I’ve used USE plastic ones from 27.2-31.6 and Post Moderne 27.2-30.9 with Easton CT2 and Ritchey WCS Carbon respectively, never had a problem.

The USE ones are good though, as they’re quite deep, the bigger issue is normally the lack of support within the frame, particularly if you run a long seatpost, nominally it voids the warranty of Spesh frames.