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Seat post size

Old 06-19-15, 03:28 PM
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Seat post size

This is a very simple and straight forward inquiry but I want to be certain before buying a new seat post for the '73 Raleigh Super Course that I am building up. The original hollow seat post is 26.3mm but that seems to be a very uncommon size and I want to replace it with a seatpost that does not require the attachment for the saddle. I see many 26.2 options such as a Kalloy. Now eould this .1 mm be an issue or could I just use a 26.2? Thanks!
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Old 06-19-15, 03:31 PM
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Seat posts a sized in 0.2mm increments, so you likely need either a 26.2 or a 26.4. Are you measuring the OD of the post or the ID of the seat tube? if the post, measure in several places and several orientations. If the seat tube, measure a couple different orientations, as brazing heat often causes the top of the seat tube to become slightly oval.
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Old 06-19-15, 03:36 PM
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I measured the post so I will measure it in a few more spots. Obviously round down when buying the post right?
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Old 06-19-15, 06:02 PM
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the bike was likely built in the UK while on the imperial system and the post is 1-1/32". Seat tube is 1-1/8" with 3/64" wall thickness.

Your decision should be based on how the current post fits. If it's a very snug fit, you have no upside room and should go with a 26.2. If it's free running fit, with maybe a bit of jiggle, go up to 26.4. If you go up, you can safely ream the tube out to a perfect fit.
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Old 06-26-15, 03:12 PM
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@FBinNY I measured numerous times and it turns out that it is 26.4 mm. I bought a Kalloy post and it fits snugly. Thank you.
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Old 06-26-15, 05:58 PM
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To add to what FB says: another option is to get a 26.4 post, try it and emery cloth it down until it fits. (I did this with a Kalloy27.s post to get to the 27.0 of my Raleigh Competition. Wasn't hard. I put it in a bench vise and tried it frequently.)

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Old 06-26-15, 05:59 PM
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Originally Posted by 79pmooney
To add to what FB says: another option is to get a 26.4 post, try it and emery cloth it down until it fits. (I did this with a Kalloy27.s post to get to the 27.0 of my Raleigh Competition. Wasn't hard. I put it in a bench vise and tried it frequently.)

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Good! You took my approach and tried it before the first emery clothing! Saved some work and anodizing.

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