Seatpost Shim

xcMuttley

Hi, i have a 30.6mm seatpost and cant find many to replace it just wondering if using a 27.2mm seatpost and a shim would be ok? Will only be using my bike for xc/trail use just wondering if anyone has had any problems using shims? Seen a few people saying they slip quite a bit when using them on mountain bikes?
Thanks

nicklouse

often it is preferable. and no they do not slip.

Northwind

Only downside I've ever found is that they can be a bit annoying when raising the seatpost- sometimes instead of the post sliding through the shim, the shim pulls out of the frame. USE thermo ones grip pretty tight, which means they don't slip but they sometimes don't like to let go!

But don't stress about it, half my bikes have shims and they do grand.

tom_fun

I have a 30.0mm frame with a shim on a 27.2 post, mine slipped all the time but I just had to do up the clamp a bit tighter.

Only down side was the clamp had to be annoyingly tight to stop it slipping and made lowering/raising the post a mild frustration.

xcMuttley

Thanks for the replys will get a seatpost and shim now instead of searching for a 30.6mm seatpost thats light weight (which im pretty sure are non existent) , Thanks again

Anonymous

All I can say about such shims is I keep seeing that many end up very well stuck in the frame so bear that in mind if you think you might want to remove it. Also seen a couple of mentions of cracked frames from shim use, carbon though (one being recent thread here about it).

As for slippage, yes you should be doing the things up fairly tight. However you can also use carbon assembly paste, even with metal frames and posts. Helps reduce slip with less clamping force.

And if you're after light weight, are you looking at carbon posts? Is the frame and/or shim metal? If so, carbon paste again else you stand to find the post bonds itself to the frame/shim and will struggle to get it out. Likewise metal post or shim in carbon frame.