Apologies for confusing the new Xootr Swift specs with the specs for the older steel frame. I had the specs for the Al Xootr Swift at hand from an email from Steve K at Xootr. According to Steve K, the new Al frames have a 40 mm seat post. I just did a rough (non-caliper) measurement of my steel Swift, a 2003, and it looks like 30 mm seat post OD, with a 27.4 mm saddle post.