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  1. #1
    Meatbomb
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    Seat Post Slipping

    I've been having an issue with my seat post slipping down as I ride. I find myself having to stop and adjust it back up at least one a ride.

    I've got it clamped as tight as I can get it and have use Fiber Grip paste on it as instructed by my LBS... Still slips down.

    Anyone have luck solving this issue?

  2. #2
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    When you say as tight as you can get it, what exactly do you mean? Is it a QR lever type of seat post clamp or is a bolt type? If a bolt type, are you using a torque wrench?

    What material is the post and what is the frame? Are both undamaged? Did the LBS inspect it and determine nothing's wrong?
    Do the math.

  3. #3
    Meatbomb
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    QR clamp, Aluminum frame, no clue of the post material. I don't see any damage in the area. LBS did not inspect, they recommended the Fiber Grip.

  4. #4
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    Is it a new seat post that is too small ?

  5. #5
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    What is the post made of?

  6. #6
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    I guess they work for others but I've been trying a quick release clamp on my CX and no matter how tight I clamp it, it slips. Granted, I probably did not clean out the grease very well.
    Quote Originally Posted by Oh My Sack! View Post
    Remember, there's always quilting and knitting if pedalling becomes too tough.

  7. #7
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    Right size post? Forgot to re-insert shim? I'm guessing that's not the problem, but we all can forget the simplest of things from time to time.

    That being said, I've had issues with QR clamps when they're dirty or just not lubed. If that's the case, clean it, put a bit of grease on the threaded rod and a drop or 2 of light oil on the QR pivot & cam (I use Boeshield T-9). Wipe of the excess. I usually take the collar off and clean that and that section of the frame, too, then a touch of grease inside the collar to prevent creaking.

  8. #8
    Gnar? I didn't see it...
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    LBS said to use Fiber paste on an aluminum frame and (very likely) an aluminum post? Uh... ok

    I'd say swap out the QR for one you torque that way you know what you're doing - even if it's temporary. Also, very light grease on the post; you shouldn't be able to see gobs of grease before you insert it.

  9. #9
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    Quote Originally Posted by bbarry404 View Post
    LBS said to use Fiber paste on an aluminum frame and (very likely) an aluminum post? Uh... ok

    I'd say swap out the QR for one you torque that way you know what you're doing - even if it's temporary. Also, very light grease on the post; you shouldn't be able to see gobs of grease before you insert it.
    No harm using carbon paste for aluminum. It gives it a bit more purchase for the same torque value, which is why it's used for carbon. The only minor downside is the grit can scuff up the seatpost, which will happen anyway especially if it keeps slipping.

    Why bother buying something if it's not necessary?

  10. #10
    Gnar? I didn't see it...
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    Quote Originally Posted by noapathy View Post
    Why bother buying something if it's not necessary?
    because:

    Quote Originally Posted by Phillbo View Post
    I've got it clamped as tight as I can get it...
    I guess to clarify, I would not recommend tightening as tight as I can get it. Using carbon ferction paste, ok... I was steering OP towards proper torque.

  11. #11
    Elitest thrill junkie
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    Most likely it's a slightly out of spec seat tube or seatpost. If you've successfully used the frame before with another seatpost, it's likely the new seatpost. You've already used the trick of carbon paste (no harm there), and all you have left is to grease the heck out of the clamping mechanism to be sure it's transferring the force, but it usually doesn't take that much on a non-dropper solid post to keep it from slipping, so likely an undersized post. If you have the correct size post, it's simply out of spec.

    If it's a non-QR, grease around the collar and grease the threads of the bolt.

    If it's a QR, grease the cam and the above stuff.

    This is unlikely to be the problem, but some cam-type QRs can get gunked up and simply not transfer enough force to hold QR wheels in tight.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  12. #12
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    Quote Originally Posted by bbarry404 View Post
    because:



    I guess to clarify, I would not recommend tightening as tight as I can get it. Using carbon ferction paste, ok... I was steering OP towards proper torque.
    If the QR is functioning properly, it should supply all the clamping force necessary so buying a new clamp to apply more without at least trying to clean/lube first seems wasteful...but what do I know? Having read Jayem's comment, an out of spec post/seat tube/both seems like the thing to look at if indeed it was replaced recently.

    OP, got a set of calipers?

  13. #13
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    Kinda need to know what he post is made of, it makes a difference. How can you have 'no clue' what it is? Not a hard thing to figure out.

    Last year I pulled a guy's 'carbon' seatpost out on the bike to put an alloy one in for clamping in the stand. Turned out is was an alloy post, with some kind of carbon-effect print on it! What the heck. Is a Specialized bike by the way and original post.

  14. #14
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    Quote Originally Posted by Mr Pig View Post
    Kinda need to know what he post is made of, it makes a difference. How can you have 'no clue' what it is? Not a hard thing to figure out.

    Last year I pulled a guy's 'carbon' seatpost out on the bike to put an alloy one in for clamping in the stand. Turned out is was an alloy post, with some kind of carbon-effect print on it! What the heck. Is a Specialized bike by the way and original post.
    But it was a great deal on eBay for a carbon post direct from China! Only suckers pay for name brand stuff!
    Quote Originally Posted by Oh My Sack! View Post
    Remember, there's always quilting and knitting if pedalling becomes too tough.

  15. #15
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    Quote Originally Posted by chazpat View Post
    But it was a great deal on eBay for a carbon post direct from China!
    Nope, came on the bike. Hi-end hybrid that has carbon seat-stays, forks and bars. Just assumed it was a carbon post as it was in keeping with the rest of the bike. Quite surprised Specialized would fit a 'fake' carbon post. Didn't even know you got such a thing.

  16. #16
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    Quote Originally Posted by Mr Pig View Post
    Nope, came on the bike. Hi-end hybrid that has carbon seat-stays, forks and bars. Just assumed it was a carbon post as it was in keeping with the rest of the bike. Quite surprised Specialized would fit a 'fake' carbon post. Didn't even know you got such a thing.
    That is odd.

    And I have to confess, I have a cheap plastic web road saddle with a carbon look overlay I bought direct from China! Honest, these saddles are the only Chinese direct parts I have on any of my bikes. I got it and thought, "why didn't I just get black?" I like them but I don't trust them on a mountain bike.
    Quote Originally Posted by Oh My Sack! View Post
    Remember, there's always quilting and knitting if pedalling becomes too tough.

  17. #17
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    Quote Originally Posted by chazpat View Post
    That is odd.
    Agree. Very unexpected.

  18. #18
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    Cheap qr's can often cause problems, sometimes even when they're cranked down super tight they don't actually tighten much. As mentioned oil or grease the cam (if applicable) or maybe replace with a bolt.

    If that doesn't help I'd try a different post like Jayem suggested, if it's an aluminum post fiber grip is a band-aid that should be unnecessary IMO.
    I brake for stinkbugs

  19. #19
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    this may or may not help, but I had a similar problem at one time. I tried everything. I measured the seatpost in various spots and found that, although it was a 27.2 mm seatpost and the frame was 27.2 mm, the middle of the post was more like 27.1 mm where it clamped. it was a black seatpost and the area where I was clamping it in the frame was clearly worn a bit thinner. I replaced the seatpost with something nicer and never had that problem again.

  20. #20
    Meatbomb
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    Post came with the bike when new. I have not changed it. I'll pull it,clean it and lube everything as mentioned.

  21. #21
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    Quote Originally Posted by Phillbo View Post
    Post came with the bike when new. I have not changed it. I'll pull it,clean it and lube everything as mentioned.
    And the post is made of?...

  22. #22
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    Quote Originally Posted by Mr Pig View Post
    And the post is made of?...
    Rigatoni.

  23. #23
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    Seriously though, what is the issue with telling us what the post is made of? The solution will depend on that.

  24. #24
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    Quote Originally Posted by Mr Pig View Post
    ... Quite surprised Specialized would fit a 'fake' carbon post. ...
    I'm not.

  25. #25
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    My vote is for a defective seat post clamp, or maybe a bike delivered with the wrong one. I have had two bikes in recent years that have had posts that slowly fall. Both were fixed with a new seat post clamp.

    On one it appeared that the QR mechanism would bottom out before fully clamping the post. Maybe it was the wrong one, especially since these things come in 38 different sizes. On the other it was a "light weight" clamp and a beefy Surly one fixed the problem.

    I think the bolt on ones hold better. Have your LBS get one for you.

  26. #26
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    Quote Originally Posted by adaycj View Post
    I'm not.
    I agree that the quality of Specialized bikes isn't what it used to be but fitting a fake carbon post is pointless and cheesy.

  27. #27
    Meatbomb
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    Quote Originally Posted by Mr Pig View Post
    Seriously though, what is the issue with telling us what the post is made of? The solution will depend on that.
    I'm not sure what it is made of. It's the original seat post and I have not had this issue until just recently and I've been ridding this bike for 5 years.

    I tried to look up the specs for the bike but the seat post is not spec'd out. I'm "assuming" it is aluminum since I doubt it is carbon since it's not a high end carbon framed bike.

    '13 Stumpy FSR Comp 29'er.

  28. #28
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    Quote Originally Posted by Phillbo View Post
    I'm not sure what it is made of. It's the original seat post and I have not had this issue until just recently and I've been ridding this bike for 5 years.

    I tried to look up the specs for the bike but the seat post is not spec'd out. I'm "assuming" it is aluminum since I doubt it is carbon since it's not a high end carbon framed bike.

    '13 Stumpy FSR Comp 29'er.
    It could be fake Aluminum!? o_0

    'Born to ride!'
    "Mountain biking: the under-rated and drug-free antidepressant"

  29. #29
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    Quote Originally Posted by Phillbo View Post
    I'm not sure what it is made of.
    Just pull it out and look at it. If it's carbon, it will look and feel like plastic. Otherwise it's alloy, unless you bought the bike in Walmart for $50 in which case it might be steel.

    Very odd that it has been ok up until now. Have you grown fatter?

  30. #30
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    Quote Originally Posted by Mr Pig View Post
    I agree that the quality of Specialized bikes isn't what it used to be but fitting a fake carbon post is pointless and cheesy.
    No argument from me. I think Specialized is the master at making their mid and low end bikes look better than they really are on the sales floor. All the way up to multiple thousands of dollars. I can't knock them for it, they rarely actually lie about the spec if anyone bothers to look on that kind of a bike.

    On the other hand, one of the bikes I had with a sinking post was a new Trek. The seat post clamp was carved out and only had two ribbons of alloy about half way around. It is nearly as ironic as fake carbon fiber. It was a 30 pound bike with a 27 gram seat post clamp instead of a 34 gram one. Fashion over function, "pointless and cheesy". I suppose they all do it to some extent.

  31. #31
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    Photos! I got to see this carbon sticker! Please!


    Sent from my iPhone using Tapatalk

  32. #32
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    Quote Originally Posted by adaycj View Post
    No argument from me. I think Specialized is the master at making their mid and low end bikes look better than they really are on the sales floor.
    I don't think they have to. I think people just assume Specialized bikes are better than they are. They built a name by making high-quality bikes then traded off it.

    Quote Originally Posted by Wacha Wacha Wacha View Post
    Photos! I got to see this carbon sticker! Please!
    It's on a friend's bike. He doesn't cycle with us, or cycle much at all, so who knows when I'll next see it. It's not a sticker, it's more like a print on the post. I didn't realize until I pulled the post out and saw that the 'carbon' didn't go all the way to the bottom of the post, and then I noticed a seam at the back.

  33. #33
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    I had this problem on my '11 FSR Comp. The cam on the stock QR seatpost clamp had a groove worn into it from repeated opening/closing (pre-dropper era). Replaced that clamp with a beefier one from Salsa and never had the post slip again.

  34. #34
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    Quote Originally Posted by Mr Pig View Post
    It's on a friend's bike. He doesn't cycle with us, or cycle much at all, so who knows when I'll next see it. It's not a sticker, it's more like a print on the post. I didn't realize until I pulled the post out and saw that the 'carbon' didn't go all the way to the bottom of the post, and then I noticed a seam at the back.
    I used to have a handlebar that sounds like what you're talking about. It was Nashbar brand and actually carbon fiber wrapped around aluminum. No idea if there was any benefit, but it worked as well as any other bar and had the cool carbon weave.

  35. #35
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    Quote Originally Posted by noapathy View Post
    I used to have a handlebar that sounds like what you're talking about. It was Nashbar brand and actually carbon fiber wrapped around aluminum. No idea if there was any benefit, but it worked as well as any other bar and had the cool carbon weave.
    Aluminum (or other metal) wrapped with carbon is a legit construction method. You can use less metal, and the carbon wrap adds stiffness. Titus did their exogrid frames for awhile, which were a fairly exotic ti/carbon laminate. Shimano does ti/carbon laminate chainrings.

    Granted, the low end carbon/alu offerings are done more for appearance than for any functional benefit. But it's a fairly common thing over the years.

    Definitely measure everything, though. Without that, you're pissing in the wind.

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  36. #36
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    Quote Originally Posted by Harold View Post
    Aluminum (or other metal) wrapped with carbon is a legit construction method. You can use less metal, and the carbon wrap adds stiffness. Titus did their exogrid frames for awhile, which were a fairly exotic ti/carbon laminate. Shimano does ti/carbon laminate chainrings.

    Granted, the low end carbon/alu offerings are done more for appearance than for any functional benefit. But it's a fairly common thing over the years.

    Definitely measure everything, though. Without that, you're pissing in the wind.

    Sent from my VS995 using Tapatalk
    I'd say sometimes, a lot of the carbon-wrapped stuff ends up heavier than a true carbon component and the benefits are usually marginal to questionable compared to a quality metal component.

    Anyway, the OP could try pouring some saltwater down his seat-tube.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  37. #37
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    At the low end, sure. It can be done at the high end to maximize benefits, but at this point, full carbon construction is at least as good, and cheaper for most things.
    Quote Originally Posted by Jayem View Post
    I'd say sometimes, a lot of the carbon-wrapped stuff ends up heavier than a true carbon component and the benefits are usually marginal to questionable compared to a quality metal component.

    Anyway, the OP could try pouring some saltwater down his seat-tube.
    Sent from my VS995 using Tapatalk

  38. #38
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    Quote Originally Posted by noapathy View Post
    I used to have a handlebar that sounds like what you're talking about. It was Nashbar brand and actually carbon fiber wrapped around aluminum.
    This one isn't that, it's a very thin print of some kind and is clearly cosmetic only. It was a 'what the heck' moment as I'd never seen anything like it. I see the guy pretty much every week and I will see the bike again, probably the next time anything goes wrong with it! I'll try and remember to take pictures.

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