After a long and protracted fight, I finally removed a seat post from an old frame of mine. bought the bike back in 1979 and it has been abused. Both son’s borrowed it for the University ‘hack’ bike. The seat post has not moved for years, so I was on the point of sending it off for recycling when I had another go at it. Much to mine (and my son’s) amazement I managed to extract it without damaging the frame. Result. It can now be used as the station hack bike.

Sadly the seat post is now just a very badly mangled tub, with some serious scaring. So it needs replacing, but it is 1″ diameter. Does anyone know of somewhere reputable to get a 1″ seat post? I know the metric equivalent is 25.4 mm, but as with all things metric/imperial I am very aware that any conversions often are not as good as should be. or is it a case of trial and error?

Maybe a Thomson?

1″ is exactly 25.4mm so you should be fine with one of those.

USE with no shim.

Try Halfords…

Most seatposts derive from imperial anyway eg the common 27.2mm came about as it was the nominal post reamed bore of a typical 1 1/8″ bike tube.

Just type “seatpost 25.4mm” into ebay and sift through all your options…

This thread got me thinking about how accurately 1 inch converted to 25.4mm, and I found this…

Nearly sixty years ago, the inch was redefined to be <b>exactly</b> 25.4 millimeters, so that conversion is now exact to any number of decimal places. Previously, the inch had been defined by setting 39.37 inches to be exactly one meter (i.e. 2.54000508 cm/inch). Prior to that, an inch had been defined to be the width of three barleycorns.

Given the tolerances of the manufacturing tolerances of both seatpost and frame, 25.4mm should be close enough 🙂

OP may I ask, how did you get the old post out ?

@loughor – brute force and ignorance. Cut a slot in the seat post and tried using a bar to rotate it. Failed. Put the seat post into a vice, squeezed tightly so that it was squashed (the cutting of the slot helped here) and twisted. Initially nothing then it moved when I put some real force in it. Then it was just a question of ‘pulling’ it out – which was a slow and painful task. Used some lubrication to help. Was helped that the seat post being removed (actually a seat pin) was quite short. Will make sure that all seat posts are properly lubed!

Cannondale CAAD12 use a 25.4mm seatpost and I think also some of the Synapses? But plenty of options on ebay

There was a time when people went to their local bike shop to buy something that has been sitting on the shelf for decades and the shop had lost hope of anyone ever asking for.

SJS have loads.