Okay, at this point this is getting rediculous.

My Astrale frame had a 25.8 seatpost in it. It was a chrome, straight post that takes a seperately clamp to hold saddle rails.

I bought a 25.8 post and it was a bear to get in. So I got a 25.6 and realized it was too ssmall. I realized the clamping area of the frame was pretty distorted and spread it back to where I figured it should be.

I put the 25.8 back in, and now it wouldn't tighten up. There was also a gap between the post and the frame tubing at the bottom of the slot.

Okay, so I got a 26.0. Well, it felt tight going in, but it also had a gap, and can be turned (though it takes quite a bit of effort).

So, I'm not sure where to go next. I can keep throwing posts at it but this thing was ridden with a 25.8 post for a lengthy amount of time (looked like possibly the original post).

It sounds like the ID of the seat tube has been distorted. The two common causes are fitting a too small post and heat from the brazing. Any burrs add to the challenge of finding the correct post, but help hold a post like studded tires help on ice.


So now I would let someone with real experience have a look at this frame. Sure you can try different posts but until you fix the root cause you're just treating symptoms and not the real issues. There's a good chance the binder ears will get damaged from trying to keep a wrong post tight. Andy.

I tend to concur with Andrew.
However, shims are an option. You can buy specific shims from one size to another, that are easy to use because they have a lip to prevent it slipping down too far, or, more cheaply, experiment with e.g. beer cans, hobby shop shim stock, or hardware store sheet aluminum.