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PostPosted: Tue Aug 20, 2013 9:19 pm 
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I've stripped the threads on my wife's 93 Hahanna seatpost clamp and have no verniers (still!). Can anyone tell me the size as I need a new one for the weekend.

Cheers :D


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PostPosted: Tue Aug 20, 2013 9:54 pm 
retrobike rider
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Pretty sure it'd be 28.6mm - same as the front mech....

SP


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PostPosted: Tue Aug 20, 2013 10:09 pm 
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Splatter Paint wrote:
Pretty sure it'd be 28.6mm - same as the front mech....

SP


That would indeed make a lot of sense :facepalm:


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PostPosted: Wed Aug 21, 2013 12:21 am 
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Splatter Paint wrote:
Pretty sure it'd be 28.6mm - same as the front mech....
SP

That may be correct in this case, but in higher-end frames the size of the fm clamp isn't the same as the seat clamp because the seat tubes are externally butted out to 29.8 at the top and where the welds are. It may be though that a Hahanna has a plain gauge straight seat tube, in which case you'd be right, but I don't know anything about Hahannas I'm afraid.


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PostPosted: Wed Aug 21, 2013 7:47 am 
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I'm saying 29.8/30mm for 1993. Is it a 27.0mm seatpost?

You can measure to 0.2mm easily enough with a steel rule, so that should put you in the ballpark or else wrap a strip of paper round the top of the seat tube and mark where it overlaps.
30mm dia. will be about 94mm, 28.6 around 90mm.


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PostPosted: Wed Aug 21, 2013 7:49 am 
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Andy R wrote:
I'm saying 29.8/30mm for 1993. Is it a 27.0mm seatpost?

You can measure to 0.2mm easily enough with a steel rule, so that should put you in the ballpark or else wrap a strip of paper round the top of the seat tube and mark where it overlaps.
30mm dia. will be about 94mm, 28.6 around 90mm.


Pretty sure the seatpost is pretty skinny, maybe a 26 something


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PostPosted: Wed Aug 21, 2013 8:14 am 
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In that case it'll be 28.6mm then


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PostPosted: Wed Aug 21, 2013 4:11 pm 
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The mathematical constant Pi (3.142) is the relationship between a circle's diameter and circumference. Therefore simply measure the external circumference of the seat tube (if you don't have a flexible tape measure you can wrap some paper around and mark it, or use a bit of string) then divide that measurement by 3.142 to get the exact external diameter of the tube.

Or... an engineering shop might be able to drill and tap your existing clamp for the next larger thread size, looks like it might be possible on a standard Kona clamp. A decent engineering shop will probably have the appropriate sized replacement allen bolt too..


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PostPosted: Wed Aug 21, 2013 4:31 pm 
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RadNomad wrote:
The mathematical constant Pi (3.142) is the relationship between a circle's diameter and circumference. Therefore simply measure the external circumference of the seat tube (if you don't have a flexible tape measure you can wrap some paper around and mark it, or use a bit of string) then divide that measurement by 3.142 to get the exact external diameter of the tube.



Mmmm - could have sworn I said much the same this morning :)


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PostPosted: Wed Aug 21, 2013 7:17 pm 
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Come on then raidan73, tell us the size!

SP


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