Alu or Plastic Seatpost Shim for R3?

[mtbnoob]

Which is better in the long run considering seatpost stability, slippage, effect to the crabon frame? The USE alu shims down from 32.4 to 31.6 (9 grams) and the USE plastic shims down from 32.4 to 27.2 (31 grams).

[mazdatech10]

i have the 32.4 to 31.6 shim and have 2 yrs with no slipping or noise

[pritchet74]

I have the carbon BTP one going down to 31.6mm. I think it weighs about 2g.

[mtbnoob]

Where can I get the BTP shim online? The BTP website is not very helpful.

[DocRay]

I've got a ally shim from 32.4-31.6, but I did have a plastic one from 32.4-27.2. both worked fine.

27.2 is too small if you run a lot of post out of the frame and are bigger.
If you are going to run a carbon post, the carbon or plastic shim is optimal, you won't have to worry about galvanic corrosion. If you use ally, anodized or not, grease/paste the shim both sides and the post, or with the thin ally the post will weld to the shim and the shim will weld to the frame.

[mtbnoob]

I currently have 14cm of seatpost sticking out of the seat tube. A 27.2mm seatpost would be possible no?

I might also just get the Campy Record seatpost and do away with the shimming hassles.

[Tube]

I use the BTP shim. It weighs 7 grams. Together with the Easton EC90 seatpost makes 186 g. Thats 99 g les than the original FSA seatpost.
At the beginning I had some trouble with it. Now its just fine. I used Tacx carbon pasta.

It took only 3 months to get the shim. Contact with BTP was very very slowly.

[DocRay]

I currently have 14cm of seatpost sticking out of the seat tube. A 27.2mm seatpost would be possible no?

I might also just get the Campy Record seatpost and do away with the shimming hassles.

Depends on your weight. but at 14 cm you should be fine.

The record seatpost is no lighter or better than the FSA, and the shim really isn't a hassle.

[mtbnoob]

Can anyone suggest a 25mm setback seatpost (31.6 or 27.2) + shim combination of decent weight (under 180grams) to replace the FSA SL-K?

Most of the really nice and light seatposts out there seem to have zero setback. No ultralight seatposts please, they're too expensive.