Thin seatpost

the post is too big. i thougt that was obvious. can i fit it in anyway? it's a simppel question.someone said i could shim it.

but the tube is to small for the post. so an external shim is perfect.

y is bigger than x - shincar - on your drawring you seeem to think its the other way round.

I is confoozed, and I think shin can be forgiven for thinking the other way round...