Titanium Seat-tube Sizing

[DWCollins]

I have a Ti CX bike with a slightly oversized seat-tube. With a coke-can shim and plenty of carbon grip paste I can get the seatpost to not slip. Are there any options I can try to open up the seat-tube to fit a 27.4 post before I take it to a frame builder?

Thanks

[Amaro Bikes]

Hi DWCollins,

Please, add your complete name for posting on "Mentor" forum (Posting guidelines)

About your question:
-First of all I would try to contact the frame builder or research information on the original specification for your frame, so to know if the slightly odd measure seatpost was standard or if the tube has been somehow deformed/damaged/modified, as solutions would be quite different depending on if seat tube is damaged/modified or not
-You could also made yourself a custom shim to be bonded on the seat tube, 10-12cm length should be enough, with a little top lip to rest on to pof seat tube. Then ream the bonded shim to 27.2mm seatpost size and use it normally.
-Reaming to 27.4mm size might have some real issues, as making the frame weaker by thinner seat tube walls at critical points, unless it has plenty of meat or externally butted top section, it might not be the best solution. Also, think about the difficult life on finding 27.4mm seatposts, etc

But as said before, first step should be making clear what's been the reason for this to happen and which were the frame originally specs so to know what your real scenario is

Cheers