First off, sorry about the double post. I do delete them if I know that's happened, but this time I didn't even realize it. bikeforums is blocked by my corporate firewall at work, so I was/am connected using my netbook and a tethered mobile data connection through which has left much to be desired over the last few days, probably the cause of the double post. I'll delete the other post.

As for the actual question, thanks for your answer. So, just tomake sure I understand, you're saying put the hardware store bolt and nut back on, stick in the seatpost, and tighten the bolt down to hold the seatpost in place, then take the same outside of the ears measurement while bolted in and subtract 3-4 mm from that measurement to determine the right size?