How well does a 30.9>31.6 shim work?

New frame is 31.6

Existing dropper is 30.9

But I’ve just found a unused USE shim in the spares box

Before I fit the internal dropper will this wafer thin shim actually keep the post from slipping?

Yes (probably). A bit of carbon paste will also help if you feel you are having to tighten it too much.

I used one for years without issue.

I used one for years without issue.

This. And just about to use one on my next frame/dropper.

I’ve been using one for a year. Some slippage necessitates adjusting post height every other ride. I suspect whether they work or not is down to the relative tolerances of the 3 parts (frames, shim and post). Luckily my reverb has just died so I can buy a proper sized one.

I used one for a couple of years with a dropper. Absolutely fine, no issues at all.

I’ve used one with carbon paste. No issues at all.

I use one on my normal post, to avoid buying a new one. No problems at all, no slippage, i weigh around 120kg.

I’ve used one and it was awfully creaky on one bike, fine in the other.

If you raise and lower your seat post a lot they get mashed quickly as they’re so thin.

I’ve never had problems with them. Sand the inside of the shim so it’s not slippery, wipe the seatpost down so it’s not greasy. I’ve never had a seatpost slip.

No problems here. Had one on my fatbike and it’s worked with both a dropper and a thud buster with no issues for 18 months.