Seatpost problem
 

I have a Bottecchia Sprinter where the seat tube diameter measures 26.19...I got a seatpost at 26.2mm but it still doesn't go into the seat tube.

Am i going to have to try a 26.0mm post?

Has the seat tube gotten pinched togethert the clamp? That would be my first check.

I suspect you measured the top ID of the seat tube but not the "ID" an inch or two down. There's a lot of potential distortion from heat and such that can change the ID shape and/or internal circumference (note I didn't say diameter). This is why when folks measure the seat post size they often don't end up with a post that fits the entire insertion amount that the post uses.


The best way to size a post is with trial and error, plain and simple. No possibility of error or assumption. The post either fits in and is loose or able to be tightened in place or it won't fit in enough. better shops keep a collection of posts in different sizes for this testing.


Also know that the post's marked size is usually a small amount under the marked size and can also vary from post to post a tad. Once again the proof is in the actual fit. Andy

This would result in a "measurement' that was under sized. not too large as the OP said. Andy

The seat tube clamp is able to expand. With the binder bolt removed the ID measures 26.19mm..with the bolt tightened the ID measures 25.97mm.

Sigh...now to get a 26mm seatpost

Why not just lightly sand down the circumference of a 26.2 post? That is what we French bike weenies do with stems. (22.2 mm to 22.0).

resolved; measurement error by OP.










....

Stronglight post is fairly thick walled.

I spent about 20 minutes sanding down the post. I wrapped sandpaper around it and in a twisting motion went at it. Little by little it did go from 26.21 down to 25.98 or so. Arms got tired aftet a while so ill take another stab at it later today

It was a 25.8!!!

Grease that sucker!

Luckily my LBS had a 25.8 to test out with my frame so I left for a tune up.