I have an iron horse tandem (Tango model), and wanted to replace the stocker seat post with a straight post with upside down clamp, for my daughter. The seat post looked like it had 26.8 stamped on it (although it was not very legible), so I ordered a seat post of that diameter, and it definitely isn't right. The original seat post fits in snugly but not tightly, while I can barely force the 26.8 in an inch or so. Do any of you have any idea what size I should be looking at? Would 26.6 be right, or do I need smaller? I could ride to the LBS, but it's not terribly convenient, and I don't know when I'll get around to it.