Tight seat post

[grateful]

i prefer a shiny Nitto post, not sanding that down.

[unterhausen]

Originally Posted by vqdriver

you could try the flex hone, but if it's really that tight, you could also just try a 27.0 post and see if that's too loose.

seems to me that scratching suggests the clearance is okay, the bore just needs to be shined up a little. Too bad the OP isn't nearby, I would let him use my flex hone. They aren't really that expensive. But I'm a little curious how a builder would let this go without fitting a seatpost.

[Peter P.]

Originally Posted by unterhausen

But I'm a little curious how a builder would let this go without fitting a seatpost.

Here's one possibility-

From using their reference (seatpost, go/no go gauge, whatever) for hundreds, if not thousands of frames, its O.D. has become worn and undersized.

It pays to check your tools occasionally.

[oldpotatoe]

Originally Posted by grateful

I have two titanium frames that both take a 27.2 seat post. One frame is very tight to the point of scratching the post in a manner that is unacceptable. Do I have any options to increase the diameter of the seat tube? It should not take much as the post is able to be installed.

Take a flexhone to it..particularly if the post is getting scratched..might be a burr where the seat stays connect to tube.
And for right below..that seattube pst flexhone gets HOT...so watch that...

[unterhausen]

btw, a 1 1/8" flex hone works for 27.2mm posts. It's a little annoying to insert. the first couple of times

[charliedid]

Just to be pedantic:

Reaming is an operation performed after drilling a hole in a work piece. This is done to remove the slight irregularity in the drilled hole and making it perfectly round.

Honing is a surface finishing operation that gives very smooth inner surface usually required for frictionless relative motion between two parts.

[benb]

I have this issue with my All City Space Horse... it's steel & I have a Specialized Carbon post in it... it's one of those Carbon posts with the leaf spring shock mechanism in it.

I haven't sanded the post.. but I'd much rather sand the post than mess with an expensive frame. Custom Ti frame is probably > $3000 and you'd rather mess with that than a Post that cost $100-200?

If it's a carbon post who the heck cares, it's going to get scratched/polished within one season if you attach a tool bag to the saddle. You ought to be able to lightly sand the post *below the insertion point* and you'll never see the scratches.

In my case I 100% don't think it's a frame problem, because I have put numerous other posts in that frame and none of the others had the issue... the Specialized post is the one that is slightly larger than it's supposed to be.

I got the post set where it needs to be and don't mess with it... so I am not doing anything about it. But it's quite hard to adjust if I actually needed to.

[cmg]

It could be that the seat post is slightly larger than 27.2. Campy posts are closer to 27.3 for example. Ream the seat tube, doesn't sound like you'll need to take off very much material.

[seanile]

Originally Posted by charliedid

Reaming is an operation performed after drilling a hole in a work piece. This is done to remove the slight irregularity in the drilled hole and making it perfectly round.

it's also what's done to seat tubes after welding twists the metal out of round.

[grateful]

Would your average shop be capable of this surgery?

[DRZRM]

I had a ti frame from a well known frame builder that did the same thing. Although some 27.2 posts would go in, the Moots I wanted to use and a Thomson I had around would not. The builder offered to hone it himself if I wanted to ship (mind you I bought the frame second hand) but suggested I have a local shop to it. He spoke directly to one of their mechanics and it was dealt with in about 15 minutes of waiting. Perfect fit.

[unterhausen]

I'm not sure what the point of pedantry is regarding this subject. A hone removes a lot less material and is significantly less likely to cut through a tube. But it sounds like that's what is needed here, not reaming. And a hone works a lot better in a tube with a slot cut in it.

I'm pretty sure there are shops that have reamers that have no business having a reamer. Do you know if the seat tube is externally butted or has a welded seat collar on it? https://www.paragonmachineworks.com/...s.html?cat=197

A seat collar is much less likely to be distorted, but also has a lot more thickness so reaming would be safer. You can tell by looking for a weld a couple of inches from the top of the seat tube.

[tctyres]

Originally Posted by unterhausen

btw, a 1 1/8" flex hone works for 27.2mm posts. It's a little annoying to insert. the first couple of times

What grit do you recommend? They have 120, 180, 240, 320, 600, and 800. I was going to guess 320, as I have a seat tube to clean up.

[unterhausen]

I have a 240 grit. Not sure if that's the best one or not. It leaves a nice smooth surface on steel. Depending on the defects you want to remove, I don't think you will be particularly happy with 320 grit. I might get another that is coarser. It doesn't remove much material

[grateful]

The frame is made by Moots and has an integrated seat binder welded in place. It sounds to me like honing is the way to go. I don't think it would take much but I don't want to remove material if possible.