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[Closed] How do you measure the length of a seatpost?

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 H
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Do you measure the length of the post to the bottom of the clamp?

I have just bought a new frame and require a 350mm seat post. I then bought one and the length of the post upto the clamp is 327mm which is too short. Are seatposts usually measured to the rails?

Thanks very much!


 
Posted : 02/09/2010 10:58 am
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bottom of post to rails usually though as ever there'll be some companies that do it differently.


 
Posted : 02/09/2010 10:59 am
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Ooh, never really thought about that. I would have thought it's the maximum length that can be inserted in the frame. I could well be wrong....

EDIT: Just measured my Thomson, which is 330mm from end to seat rails. Others may measure up differently.


 
Posted : 02/09/2010 10:59 am
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Wot clubber said


 
Posted : 02/09/2010 11:01 am
 H
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Hindsight is a wonderful thing 😉

I knew I should have asked on here first - Thanks for your help!


 
Posted : 02/09/2010 11:05 am
 br
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You'd have been better buying a 400mm anyway, as it sounds like you'll still have too little in the frame.


 
Posted : 02/09/2010 11:22 am
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Yep, it's length of whole post, not to minimum insertion mark.

I'd say the frame is maybe a touch too small for you if you need 350mm of post sticking out!


 
Posted : 02/09/2010 11:49 am
 H
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Sorry i shoudl have been a bit clearer - I dont need 350mm sticking out!

The frame takes a 30.9mm post so lined up a 27.2mm post from another bike and decided that a 350m post would be ideal. However I was measuring to the top of the post not the rails. The 'missing' 23mm from my measurements therefore puts the post above its max.

Thanks for your help


 
Posted : 02/09/2010 2:02 pm
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If you're using a shim then the length of the post below the shim is almost irrelevant as it won't be in contact with the seat tube.

Make sure you use a shim that drops as far down into the frame as possible.


 
Posted : 02/09/2010 2:05 pm

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