Hi,

I took the risk with a CS-406 27.5 carbon frame from http://www.xmcarbonspeed.com/Productinfo.asp?f=1465
But I don't know what size seat post or clamp to buy. I asked Peter and was told a 34.9 mm clamp, but it's way too small. I had  to buy some calipers to get a good measurement and got 37.1 mm from it, which doesn't look to be a size for the clamp that anybody uses...
Also, the seat post I bought is 31.6 mm but it's a bit loose. I can't tell if it might tighten up enough with the clamp, but it's definitely looser feeling than any in my other aluminum bikes where I would need to actually push it in.  This would just free fall to the bottom with a 31.6 mm.
Has anybody built one of these or have any experience dealing with this? I knew this was a risk, but geez, I didn't think I'd be struggling to get a seat post to fit.

Rob