27.6mm seatposts

Ever seen one? no me and im needing one now
I finally decided to try to find out the correct size for my ti frame because the 27.2mm leaves a bulge at the back which means its the incorrect size ive fitted and tbh thats asking for trouble in the form of a frame ruining crack
Popped down to the local mechanic and using his seat tube gauge worked it out to be probably in the region of 27.6.
The post i have in at the mo is a 25.0mm USE sus shimmed using a USE shim to 27.2mm
What i intend to do is buy a couple more of the shims. one at 27.4 and one 27.6
The ring gauge put it at 27.4 mm but if the wrong size has been in there for so long its safe to assume the top is bent in slightly and the 27.6mm would be the better size even though it might take a little persuasion to make it fit.


Anyone else use this oddest of sizes of post? If so please let me know because im steering clear of the seat clamp issue thats probably about to surface, but any advice is very welcome.

i wouldn't recommend forcing in the larger size.

check the sheldon brown site - it lists bike manufactuere's and seat post sizes - have you been able to contact the manufacturer of the frame?

02gf74":27c62ljm said:

i wouldn't recommend forcing in the larger size.

check the sheldon brown site - it lists bike manufactuere's and seat post sizes - have you been able to contact the manufacturer of the frame?

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Naw,sheldon isnt likely to have this one so little point checking.But if you want to......

Russian,good ti(6/4 equivalent) hand made, not many produced. er.. company still going i think but its been a nightmare to find out anything because i dont speak Russian and translations werent going too well :? Spoke to a friend of a friend im not even completely sure the name of the maker and frame came across too well.

We used a proper post gauge and the 27.4 was easily accepted but ill do you a pic and youll see what i mean.

You need something like a telescopic bore gauge to measure accurately below the crimped section.
How does the seat tube gauge work?

I've never understood why some manufacturers cannot stick to industry standards when it comes to seat tube diameter. Peugeot were a classic example using posts less than 25.4 but greater than 22.2 making aftermarket posts near to non existent !

yes the multitude of different set post diameters is a pet hate of mine - they should be standardised to 3 or 4 different values like wheel diameter or hub spacing.

Rampage":b1yqh3tc said:

You need something like a telescopic bore gauge to measure accurately below the crimped section.
How does the seat tube gauge work?

Click to expand...

Think of a long cone shape but in gradual steps

Like a step drill?

Rampage":3o3ns23n said:

Like a step drill?

Click to expand...

This is it.
http://www.sjscycles.co.uk/weldtite-pro ... prod27093/

These have been out for a very long time. Its also called a 'ring gauge' After googling it i found the above and lots of other bike seatpost gauges in metal and some older ones from the BMX museum :?

Oh, same a a ring gauge for wedding rings etc.
The problem with the it that they measure at the to where it can get distorted