Shim required between seatpost (28.6mm) and tag-a-long bracket (31.6)

my google fu is struggling and im close to going the other way and buying a 27.2mm post and shim to 28.6mm

or buying a bike with a 31.6 post (for my BIL)!

All you need is a shim which will make up 3mm difference so 27.2 to 30.2 should be ok if you can find one. As it’s for clamping something on the whim will be crushed and any slight diameter difference will be taken up easily.

ah, good thinking, cheers