Update: I have a 25.4 mm seatpost, but need to open up the top of the seat tube.
So someone paid me to take this frame (basically, I bought a bike from them and they threw in the frame. I sold the bike for more). Anyway, I wouldn't have paid for this frame.
It's rusty, it's dusty, the bottom bracket was basically mud, it's missing the fricken seatpost top clamp, and on top of that, the nut to clamp the seatpost into the frame is round.
Well I don't mind the rust and dirt that much. I repacked the bottom bracket (getting those cranks off sucked. Heat is my friend.) and got down to business with some more free fixed gear parts.
Now, enough of the story. I don't dig that I don't have a seat.
I despise this style seatpost, even if it had the top clamp I would replace it because the bolts stick out the sides and rip your clothes if you run a thin (in width) saddle. (not my pic)
I measured the inner diameter approximately: 24.5mm. Might be 25. Does this sound right? Can I use a 25.6mm seatpost here?
Any help would be appreciated. Ebay posts this size are ridiculously priced. I'm probably heading down a bicycle boneyard with the derailleurs off the frame to trade for a seatpost.