Trek seat clamp size ?

[shinobi]

Hi guys
Can anyone confirm the seat clamp size on the Trek 8700 shx ?
I have a 30mm and a 34.9 mm and 31.8 none of which fit :facepalm:
It takes a 27.2 seat post if it helps ?
It seems to be 33mm ? Never heard of that size before !
Cheers Paul

 

[Smithjss70]

Hi guys
Can anyone confirm the seat clamp size on the Trek 8700 shx ?
I have a 30mm and a 34.9 mm and 31.8 none of which fit :facepalm:
It takes a 27.2 seat post if it helps ?
It seems to be 33mm ? Never heard of that size before !
Cheers Paul

Paul,

Is it a carbon/alum frame like this? http://mombat.org/MOMBAT/Bikes/1991_Trek_8700.html

Technically, it depends on the thickness of the seat tube/frame material. The internal diameter of the seat clamp corresponds with the external diameter of the seat tube – too big, and the seat post may move in the frame, with the risk of cracking; too small and the collar can’t fit on the top of the tube (and you might damage your frame in trying to force it on). The five standard seat tube diameters on the market: 28.6mm, 30.0mm, 31.8mm, 34.9mm, and 36.4mm, so once you know the size of your seat tube (measure with a calipers or check your manufacturer’s specifications) make sure to buy a seatclamp that matches.

A 27.2mm seatpost fits inside a 28.6mm diameter seat tube, so it’s a 28.6mm clamp you need.You need to put a caliper on it ideally.

 

[shinobi]

Hi guys
Can anyone confirm the seat clamp size on the Trek 8700 shx ?
I have a 30mm and a 34.9 mm and 31.8 none of which fit :facepalm:
It takes a 27.2 seat post if it helps ?
It seems to be 33mm ? Never heard of that size before !
Cheers Paul

Paul,

Is it a carbon/alum frame like this? http://mombat.org/MOMBAT/Bikes/1991_Trek_8700.html

Technically, it depends on the thickness of the seat tube/frame material. The internal diameter of the seat clamp corresponds with the external diameter of the seat tube – too big, and the seat post may move in the frame, with the risk of cracking; too small and the collar can’t fit on the top of the tube (and you might damage your frame in trying to force it on). The five standard seat tube diameters on the market: 28.6mm, 30.0mm, 31.8mm, 34.9mm, and 36.4mm, so once you know the size of your seat tube (measure with a calipers or check your manufacturer’s specifications) make sure to buy a seatclamp that matches.

A 27.2mm seatpost fits inside a 28.6mm diameter seat tube, so it’s a 28.6mm clamp you need.You need to put a caliper on it ideally.

Hi and thanks for the reply , it's a carbon / alloy lug frame . The carbon seat tube is a standard 34.9 size but the seat clamp area of the lug is machined down , I don't have a vernier but a ruler seems to be 33mm
I have been searching and apparently Saracen used that size clamp so I was hoping they were not alone lol !
Cheers Paul

 

[02gf74]

, I don't have a vernier but a ruler seems to be 33mm
I have been searching and apparently Saracen used that size clamp so I was hoping they were not alone lol !
Cheers Paul

Cut a strip of paper 5-10 mm wide and wrap it round the tube clamping area so it overlaps. Take a pencil or marker to draw a line across the edges.

Use the aforementioned rule to measured distance between the two marks. Divide by 3.142 and there is your diameter. If you can measure to within 1 mm, youll be 0.3 mm out at most.

Didnt they teach you pythagoras at school? :facepalm:

 

[shinobi]

, I don't have a vernier but a ruler seems to be 33mm
I have been searching and apparently Saracen used that size clamp so I was hoping they were not alone lol !
Cheers Paul

Cut a strip of paper 5-10 mm wide and wrap it round the tube clamping area so it overlaps. Take a pencil or marker to draw a line across the edges.

Use the aforementioned rule to measured distance between the two marks. Divide by 3.142 and there is your diameter. If you can measure to within 1 mm, youll be 0.3 mm out at most.

Didnt they teach you pythagoras at school? :facepalm:

Ha ha ! They might have done ? I will have to ask someone who was there

 

[LikeClockwork]

Re:

I was convinced I had a 33mm one in my bits box but can't find it anywhere now. There's a 34mm, but sounds like that may not help much....I'll keep looking!