To ride comfort?

Thinking of shimming a 27.2mm rather than using a 31.6mm

Interesting…

I've run 27.2mm and 31.6mm over the last few years. At my weight (10st), I don't think I can detect the slightest difference. There's movement in seat rails, tyres and so on going on, but I've never felt anything that I identify as seatpost flex. I'd guess that how the post is machined internally makes more difference than diameter alone too.

And shims are a PITA. 🙂

I use shims rather than shelling out for different size posts. The USE ones are very good. Not sure how much difference a smaller post makes to comfort though.

increasing a tube's diameter by 10% increases stiffness by 30% if you keep the wall thickness the same.

For the same weight, a 10% larger tube will be around 20% stiffer.

My 27.2mm ti post flexes so much, I swear I have to point the saddle nose down to compensate.

Just go and ride the bloody thing instead of worrying about it.

My 27.2mm ti post flexes so much, I swear I have to point the saddle nose down to compensate.

Are you sure that's the seatpost 'flexing' just because it's Ti? 😉