Titanium seatpost - tight fit?

[eurodude]

So I got this very nice custom titanium seatpost. But it seems a bit oversized? I tried it on 3 different frames now. The builder says he has no problems and I could ream or hone the seattube on my frame(s) but is this normal with titanium seatposts - I guess that most buiders “just” use a standard tube and it might not be perfect size?

[ParkerMusselman]

Take a pair of calipers to the post and find the diameter. If you don't have a pair, any competent shop will.

I'd also inspect the base of the post. It might have a pushed up burr or some displaced material that make it hard to insert.

[ERK55]

I’ve experienced 2 instances where a seatpost could not be inserted. One was a Deda alloy post; the other was a titanium post the name of which escapes me. In both cases the post was a fraction too wide. In both cases a different post could be inserted easily. My guess is you’re going to need to use another seatpost.

[David Kirk]

As stated above you need to get an accurate measurement of the seat post diameter.

One also needs to remember that a 27.2 seat post should not measure 27.2 mm. A 27.2 post is sized to fit into a seat tube with a 27.2 inside diameter so it needs to be slightly smaller. A post labeled as 27.2 should measure 27.1 to 27.15 mm outside diameter.

dave

[Soloist604]

I had a very similar (if not identical) problem a few months back. Had a custom frame made in Ti and needed a 27.2mm seat post for it. Ended up going through a bunch of different posts before I found one that was suitable. As noted above, the INTERNAL DIAMETER of the seat tube is 27.2mm so the seat post needs to be marginally smaller. The post that worked for me measured up at around 27.11mm with a set of calipers but I had to go through a few before I found one that worked. I'd be hesitant to have your builder ream out the seat tube without first exploring different options - once you have it reamed you can't really go back...