odd thing with seatposts...

[bigdawg]

fitting my new frame at the weekend and had an oddthing with seatposts. Ive got 2 410mm 27.2 thmpson seatposts, they initially went in then just jammed about 6inches in... odd this is def a 27.2 frame - tried the two 27.0 posts I had and they went and I could move them (rattle) around in there...

Any clues, the frame looks clean in there, plenty of grease with them???

 

[We_are_Stevo]

Try it without the grease, you could be getting hydraulic lock - alternatively could be that the tubes are butted? Or is the post coming up against the weld for a bottle boss?

 

[bigdawg]

not that far in for them to hit the bottle bolts... Pretty sure theyre not butted as its def a 27.2 frame - Im sure Ive got a syncros 27.2 somewhere Ill try it without grease and try the other post too...

 

[nodding dog]

Is it possible that the seat tube has developed a very slight bend?

You can check by placing a steel rule next to the tube and checking for daylight.

Also, Thompson stuff is machined to very fine tolerances so any debris or a tiny dent in the seat tube will make it bind.

 

[bigdawg]

im sure theres no bend mainly because the 27.0 I can actually move backwards & forwards in there - in fact the 27.0 will fall straight down to the clamp and still be loose..

 

[legrandefromage]

internal butting, inconsistencies in the tubing, old seat post remains(thats happened a few times), bent seatpost, internal corrosion...

 

[MikeD]

Also, Thompson stuff is machined to very fine tolerances so any debris or a tiny dent in the seat tube will make it bind.

Thomson posts tend to be fractionally smaller than other posts of the same stated diameter, if anything.