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Old 07-09-12, 12:48 PM   #1
gurp13
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Replacing my carbon seat post?

I have a 2006 Specialized Allez Elite that came with a Pavé II FACT carbon seatpost (with "Zertz" inserts). So, I have about 1500 miles on this bike, or so. I have been off it for a while but am cycling again. Last week, I was adjusting the seat height and while tightening the clamp, I overdid it, I guess, because I heard a kind of cracking noise. I looked at the seatpost but I don't see any damage. Do I need to replace it anyway?

I am thinking of getting a Thompson Elite to replace it. Is there a problem putting an aluminum seatpost in this bike instead of carbon?

Thanks in advance. I have been googling this question but haven't seen anything.
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Old 07-09-12, 01:30 PM   #2
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.. I overdid it, I guess, because I heard a kind of cracking noise..
Damage may have been to the frame.. did you use a Torque wrench..?
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Old 07-09-12, 02:02 PM   #3
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There's no problem with an aluminum post in a carbon frame, the opposite, but be sure to use either an antiseize or carbon assembly paste to prevent galvanic corrosion. The assembly past has the added benefit of improving traction so less clamping force is needed, so it would also make sense for carbon/carbon posts.

Now your first step is to determine the cause of the crack you heard. If you're lucky it'll be the replaceable clamp band, less lucky, you need a post, and if very unlucky, you cracked something on the frame. If the frame has built -in pinch bolt tear (rare in carbon frames) you may have cracked the tube or ear at the base, and will have a modification so you can change to a clamp band system.
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Old 07-09-12, 02:32 PM   #4
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Yeah you might have cracked your frame. There is very minimal torque needed for a seatpost if you install it correctly. Inspect the frame before you ride it again.
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Old 07-09-12, 03:17 PM   #5
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The frame is aluminum. Is it possible I cracked the aluminum before the carbon?

No, I didn't use a torque wrench. This is my bad, I know. I don't have one. I guess I better start shopping?

Thanks for the replies.
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Old 07-09-12, 03:49 PM   #6
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blind guesses [occasionally educated] are all we can offer here ..

Really, need an in-person inspection...
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Old 07-09-12, 03:58 PM   #7
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I realize that. I was just hoping someone had some experience. I would not have guessed that you could crack aluminum against carbon fiber.
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Old 07-10-12, 08:20 AM   #8
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I realize that. I was just hoping someone had some experience. I would not have guessed that you could crack aluminum against carbon fiber.
The most stressed part of the system is the pinch bolt ear, so anything can crack. We can't help you here. You heard the crack, so you need to try to find the source of what you heard.
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