I have a nice carbon 27.2 seat post is it ok to fit a shim so it it fits my 30.9 ti frame

I wouldn’t risk it, its not what shims are for!

What are shims for, lightman?

eh?

What!

I have a 27.2mm dropper post on my 5 (filing cabinet to stop the jokes just now) I also use it on my specialized 30.9 with a shim and my Kona (whatever the size is) with a shim. Evidently I am doing summit wrong please advise me of the errors of my ways. ta muchly.

How far up does your seat tube go above the top tube?
Personally I like my 10mm below the top tube.
I could be wrong though.

Seatpost shims have their place, but that place is not on a smart Ti frame.
You can afford a nice frame and a nice seatpost, so just do things right and get the right post for the bike.

Recall there’s a piece in Zen and the art of motorcycle maintenance that comes to the opposite conclusion. Ti was not involved though.

I think I already know the answer to my own question.as the ti is my third bike I was trying to keep costs down, so I think I already know I need a 30.9 dropper, any offers 🙂

Not sure of Ti-Carbon, but I always prefer to use shims in steel frames to prevent the dreaded galvanic corrosion and seizing of the seatpost.

In my eyes, Nylon shims are the best due to their inert qualities.

Seatpost shims have their place, but that place is not on a smart Ti frame.

Rubbish. It’s a ti frame so it will break. A seatpost shim is unlikely to accelerate that.

Was my sarcasm not that obvious!
Its what shims are for, why would you need to ask :/
Just make sure you get a decent one.

Nothing wrong with mine 27.2 ti post in a 31.6 in fact that is what I wanted

Nothing wrong with mine 27.2 ti post in a 31.6 in fact that is what I wanted

that place is not on a smart Ti frame

Many ti frames have a shim of sorts built into the seat tube anyway.
As long as the shim is long enough, no problem. I like the USE plastic shims, less easily scratched posts, no seizing or creaking.

My Scott road frame came with specific instructions not to use a shim or it would void the warranty.

The one i’am using above is the use thermoplastic shim with use sumo ti post, perfect and as James above says protects post from scratches and no creaking

Used the USED plastic shims before with no issues. Also used a Superstar shim which was ~10mm longer if you need the extra length.