Seat post clamp and slipping carbon post
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  1. #1
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    Seat post clamp and slipping carbon post

    I have an Orbea with alu front triangle, carbon rear triangle and Zeus Zaga carbon seatpost, which is clamped with an Orbea seat post clamp. On smooth roads, tightening the clamp to the point where the seat post does not slip is not a problem. On rough roads, the post tends to slide down. At a rest stop the other day, I tightened the clamp bolt some more and the bolt head snapped off. Found an LBS that removed the remaining bolt from the clamp and gave me a new bolt. Still having the problem of slipping post, and now I'm afraid to really tighten the bolt.

    Even at the point where I snapped the bolt, the two ends of the clamp were not touching. Are these just lousy clamps or do I need to look for a stronger bolt?

    For what it's worth, the seat post is 31.6mm in diameter and the LBS thought the clamp was 31.8mm in diameter. Also, the seat post slides into the seat tube very easily - maybe even too easily; wondering if a 31.7mm post (if they even exist) would fit. But since the clamp ends aren't touching, I don't think it would solve my problem.

  2. #2
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    Repeat the question

    Quote Originally Posted by serpico7
    I have an Orbea with alu front triangle, carbon rear triangle and Zeus Zaga carbon seatpost, which is clamped with an Orbea seat post clamp. On smooth roads, tightening the clamp to the point where the seat post does not slip is not a problem. On rough roads, the post tends to slide down. At a rest stop the other day, I tightened the clamp bolt some more and the bolt head snapped off. Found an LBS that removed the remaining bolt from the clamp and gave me a new bolt. Still having the problem of slipping post, and now I'm afraid to really tighten the bolt.

    Even at the point where I snapped the bolt, the two ends of the clamp were not touching. Are these just lousy clamps or do I need to look for a stronger bolt?

    For what it's worth, the seat post is 31.6mm in diameter and the LBS thought the clamp was 31.8mm in diameter. Also, the seat post slides into the seat tube very easily - maybe even too easily; wondering if a 31.7mm post (if they even exist) would fit. But since the clamp ends aren't touching, I don't think it would solve my problem.
    Seat post slipping gets posted ALL the time. A search will show you the light. Standard advice is hair spray on a clean post. The clamp gap should never be closed when the bolt is tight.

  3. #3
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    Thanks Kerry. Just picked up some hairspray.

  4. #4
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    Quote Originally Posted by serpico7
    Thanks Kerry. Just picked up some hairspray.
    You also might want to get one of those clamps that has a steel rod that the bolt screws into... they allow a higher clamping force and do not bend the bolt.

  5. #5
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    This is a real common problem for sure. I used Permatex Hylomar HPF- a non-permanent gasket dressing available in automotive stores. This was recommended in a couple of searches that I did. I also see that FSA has come out with something called Install Compound for carbon seat posts. Glory Cycles has it on their website at www.glorycycles.com but maybe you can also find it at your LBS. I also used a torque wrench because I had the value for the collar/post I was using and found out that I had drastically under tightened the collar because I had also snapped another one previously. Good luck!

  6. #6
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    So far, so good with the hairspray. I'll have to see if it holds up on bumpy roads. If it works, it'll be a lot cheaper than some overpriced "bike" solution.

  7. #7
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    If the hair spray doesn't work both the products I mentioned cost less than $6.

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