Hors Categorie Seatpost Collar size?

[A1A]

I've looked around and don't seem to see a definitive answer. Looking for advice on the correct Thomson seatpost collar size for my 99' Hors Categorie. I've been using the stock Serotta clamp for years with a Campy carbon seatpost but decided to change saddles. To get the correct reach to the bars back where it should be I ended up ordering a new 27.2 Thomson inline seatpost. I had never really realized the Campy was in some respects a setback post via the clamp design. So then I was reading the Thomson warning about making sure the collar you use doesn't touch the seatpost (the inside of the lip at the top that keeps it from sliding down the seat tube). I looked and I don't really see any clearance with the Serotta clamp although looking at the carbon post I don't see where there is any indication that the Serotta clamp damaged the post. But better safe than sorry I thought so I took my new backup Thomson 29.8 collar (I've been using one on my 1998 Legend for a long time) and plopped it on the Hor's seat tube thinking I'd be good to go but I can't tighten it down enough to secure the seatpost! The collar "tabs" (where the screw pulls them together) tighten against themselves before really tightening the seatpost enough even though I can see daylight in the slot under the clamp which means it can tighten down more. I did notice that the Thomson 27.2 post slides into the seat tube much more easily thatn the Campy did. So that seems to tell me that the gauge of the Ti on the Hor's is thinner than on the legend? Or the Thomson post is a small 27.2. Very strange, at least to me. So the next size Thomson collar down is 28.6, does anyone have an opinion if that size should work? I put the Serotta clamp on for the moment but of course now I'm a little paranoid about the top of the collar potentially damaging the seatpost ala Thomson's warning... And here I thought this was going to be so easy. I always thought the Legend and the Hor's were identical other than the funky Hor's rear end... Thanks for any advice forthcoming.

[godfrey1112000]

This may help

[A1A]

So I measured the seat tube OD tonight which is about 29.3 mm. Explains why a slightly small Thomson post (27.08 mm) coupled with a 29.8 collar over a 29.3 seatube won't let me tighten enough to keep the post from slipping. So I had already gone ahead and ordered a 28.6 Thomson collar this morning but no idea if it will slide over the seat tube. Or let me insert the seatpost. Any chance based on these measurements if it should work? Thanks.

[beungood]

Did it work?