Trek seat clamp size?

[Iwasgoodonce]

Guys,
How do I find out the size of my dad's Trek 930 seat clamp? I have the original one but can't find anything stamped on it. I am suspisious of using my (so called) micrometer as it does not seem to very good. Does anyone know of a website I can look it up one or does anyone have an old catalouge? The bike is 'wild plum' colour, has canti brakes and a lugged frame:

Thanks.

 

[sastusbulbas]

Should this not be in teh wanted section too? LOL to myself.

 

[sastusbulbas]

The original seat clamp may have a number on it, such as 31.8 or 32.

I am sure its 31.8?

27.2 seat pin?

 

[sniperworks]

The seatpost is almost certainly a 27.2, had several old treks and all where 27.2 (ranging from low en (800 series) to the 2 9900 I have (had)

Doesn't it have a fixed seatpost collar?

 

[Iwasgoodonce]

The seatpost is almost certainly a 27.2, had several old treks and all where 27.2 (ranging from low en (800 series) to the 2 9900 I have (had)

Doesn't it have a fixed seatpost collar?

It has got a removable collar with nothing stamped on it. The post size is 27.2 though. I'm just going to take the whole thing to the LBS.