Seatpost Questions

[Nooch]

Picked up a cheap Kalloy Uno seatpost -- does anyone know off hand if the section where the clamp joins the post causes for a slight 'bulging' (for lack of a better word) to go past the nominal 27.2 diameter?

Situation: I picked up that Primus Mootry aero road frame (http://forums.thepaceline.net/showthread.php?t=154827), and thought I had issues with the post length wise, but took three inches off of it and it's till not inserting the extra two cm's I need to make the fit work... I don't have a caliper to check (or string and a ruler, at the moment) so I figured I'd see if anyone might have any insight!

Additionally -- does anyone have a thought as to how much post I actually need when the tube extends above the top tube? I always work with a few inches below the top tube, but with so much material is it even necessary, or can I just stick a stump of a post in to get the clamp?

Thanks!

[oldpotatoe]

Picked up a cheap Kalloy Uno seatpost -- does anyone know off hand if the section where the clamp joins the post causes for a slight 'bulging' (for lack of a better word) to go past the nominal 27.2 diameter?

Situation: I picked up that Primus Mootry aero road frame (http://forums.thepaceline.net/showthread.php?t=154827), and thought I had issues with the post length wise, but took three inches off of it and it's till not inserting the extra two cm's I need to make the fit work... I don't have a caliper to check (or string and a ruler, at the moment) so I figured I'd see if anyone might have any insight!

Additionally -- does anyone have a thought as to how much post I actually need when the tube extends above the top tube? I always work with a few inches below the top tube, but with so much material is it even necessary, or can I just stick a stump of a post in to get the clamp?

Thanks!

Something in the frame preventing it going down? Twice the diameter of the top tube below the bottom of the top tube...general rule of thumb for the bottom of the seat post. So if the top tube is 2cm in diameter, 4cm below the bottom of the top tube for the end of he seat tube.

[Nooch]

Something in the frame preventing it going down? Twice the diameter of the top tube below the bottom of the top tube...general rule of thumb for the bottom of the seat post. So if the top tube is 2cm in diameter, 4cm below the bottom of the top tube for the end of he seat tube.

OP -- even with the big mast extension?

see:
https://farm4.staticflickr.com/3856/14932026559_33d57fa344_z.jpg
(https://flic.kr/p/oKuxgM)Untitled (https://flic.kr/p/oKuxgM) by TrickImaging (https://www.flickr.com/people/54300653@N02/), on Flickr

Nothing blocking it from going down -- If there were it would have sat a bit higher before I took the 3 inches off the bottom of the post..

[oldpotatoe]

OP -- even with the big mast extension?

see:
https://farm4.staticflickr.com/3856/14932026559_33d57fa344_z.jpg
(https://flic.kr/p/oKuxgM)Untitled (https://flic.kr/p/oKuxgM) by TrickImaging (https://www.flickr.com/people/54300653@N02/), on Flickr

Nothing blocking it from going down -- If there were it would have sat a bit higher before I took the 3 inches off the bottom of the post..

No, not with the seat mast, the 'rule'....but try another post. I sold a fair number of Kalloy posts and never had a problem....sure there isn't something butted or fatter in the mast?

[Nooch]

No, not with the seat mast, the 'rule'....but try another post. I sold a fair number of Kalloy posts and never had a problem....sure there isn't something butted or fatter in the mast?

Can't imagine it's in the mast -- seatpost stopped going down at the same point (on the post), regardless of the 3" I cut off -- so I'd have to figure the butting is at the top of the post keeping it from going deeper.. (of course, not usually an issue in a traditional frame).

So with the mast, OP -- how deep do you figure it's gotta go? I had some other options for posts when I posted the WTB, but wasn't sure if some would be too short...

[nicrump]

no caliper? hold the edge of a small machinist rule along side the post in various spots(parallel to the post axis)and look for gaps and lumps and whatnot.

[Peter P.]

If the head of the post is press-fit onto the shaft, I could understand a slight bulge.