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Old 12-30-06, 06:58 PM   #1
crypticlineage
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Stubborn Cannondale seat tube

Cannondale 2.8 Frame from 1996

I could not get the carbon seatpost (27.2) in even a bit after the minimum insertion line, but that's obviously not enough because the seatpost is 350mm.

So with the help of a friend, we sanded down inside of the seat tube this afternoon with a drill, that is still not very helpful. Finally we were able to get a aluminum seatpost in after greasing it a bit, but I would really like to use my carbon seatpost.

Any ideas on how to take care of this problem?
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Old 12-30-06, 07:24 PM   #2
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This might be real obvious, but have you tried spreading the clamp a bit?
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Old 12-30-06, 07:53 PM   #3
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We were trying with clamp off. Also, there are no signs internally or externally of damage to the seat tube.
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Old 12-30-06, 08:02 PM   #4
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There is some tolerance in both seatpost and seat tube diameters and if you have a maximum diameter seatpost along with a minimum diameter seat tube you are going to have problems even if both are supposed to be 27.2 mm. Can you try another seatpost to see if it fits better? How about a 27.0? Can the seatpost be sanded down slightly?
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Old 12-30-06, 08:14 PM   #5
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Well we tried the aluminum seatpost, and it is working okay now, but it is still pretty tight.

I would really like to use my new carbon seatpost which is 27.2. Do they even seatposts that are 27.0? Besides 2mm different sounds like a lot when talking about seatpost.
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Old 12-30-06, 08:19 PM   #6
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Quote:
Originally Posted by crypticlineage
Well we tried the aluminum seatpost, and it is working okay now, but it is still pretty tight.

I would really like to use my new carbon seatpost which is 27.2. Do they even seatposts that are 27.0? Besides 2mm different sounds like a lot when talking about seatpost.
Well, it's 0.2 mm (not 2.0 mm) or 0.008" so that's not much diameter difference. Yes, 27.0 mm seatposts are available but possibly not in carbon or the model you want.

If a 27.2 mm Al post fits (they are supposed to be snug but not "hammer-it-in" tight) it sounds like the carbon post you have is oversize despite the size marking.
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Old 12-30-06, 08:43 PM   #7
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It kind of sounds to me like the frame's not intended for a 27.2mm seatpost. Maybe it's supposed to take a 27.0 (a fairly common size also). If you're using the correct size post, it shouldn't be a struggle to get it in. Maybe tight, but not the type of struggle you're describing-

edit: just checked Sheldon's seatpost database, looks like it should be a 27.2 as you say-

Last edited by well biked; 12-30-06 at 08:56 PM.
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