Just checking off my BMX production drawings and the tube spec is 31.8 diameter with a 2.2mm wall thickness giving an ID of 27.4 for a 27.2 seatpost. To me that sounds far too big and measuring both my other bikes that have 27,2 posts it seems it is.

What do you have/what would you spec?

Cheers

Gary

You need something that comes up under the eventual diameter you want so it can be reamed out to the exact value.

Yes that was my assumption in the first place which is why I’m wondering why the tube IS is oversize in the first place. I’ll pull them up on it.

Just checking off my BMX production drawings and the tube spec is 31.8 diameter with a 2.2mm wall thickness giving an ID of 27.4 for a 27.2 seatpost. To me that sounds far too big and measuring both my other bikes that have 27,2 posts it seems it is.

I agree. 27.2 should be 27.2.