Can't stop seat post from slipping- Mtbr.com
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  1. #1
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    Can't stop seat post from slipping

    2014 soma b side frame. Race face turbine post. Hope quick release tube clamp. Thin coat of anti seize on tube to prevent corrosion. The thing always slowly creeps down. I cranked that baby as tight as I could get it. Today after a ride I greased the qr lever and bolt so it works smoother allowing me to go a bit tighter but I haven't rode enough since then to see if it is fixed. The other day I was riding one handed and the post collapsed all the way down. Since tightening it more it now just creeps down slowly over time. On a 15 mile ride today mostly flat and some highway I had to raise it back up 5 to 6 times. I weigh 170. Help?

  2. #2
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    I'll ask the obvious question. Are you sure it's the right size? The Soma specs show 27.2.
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  3. #3
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    you may want to measure the ID of the seat tube and the OD of the post with an accurate digital caliper. just to make sure you have what you think you have. if the seatpost is a little too small it will not clamp properly no matter how tight it feels.

    i recently put a Hope qr on my SS as well. it took me a few tries to realize how fine the threads are on the adjustment. mine slid down for the first ride or two, only a little though.

    other than that, i've never used anti seize in the seat tube, always used a big glob of grease. put it in the seat tube and not on the seatpost.

    if everything is lubed properly, and nothing is binding, then it should work fine. if your still having problems, i would guess it's the seatpost diameter being too small?
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  4. #4
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    One of the two could be out of spec. Wouldn't be the first time.
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  5. #5
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    I've had some frames (Gunnar...) where I couldn't get the seat post to stay up. I ended up using a pop can shim to make up the difference.

    I just ran into the opposite problem tonight: I splurged on a Thomson seat post for my latest build, but it measures closer to 27.3 than 27.2. It won't go into my frame. And here I was all happy to be buying something made in the US... hmmm, like the Gunnar. This is disappointing.
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  6. #6
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    so, a double-sided question to address both posters:

    Is your frame over reamed?

    Is your frame under reamed?

  7. #7
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    My frame is 27.2 or slightly over, the Thomson post is simply too large (measured with calipers at 27.3). I was finally able to install it after wiping off all the grease and pounding it in with a mallet.

    Quote Originally Posted by razardica View Post
    so, a double-sided question to address both posters:

    Is your frame over reamed?

    Is your frame under reamed?
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  8. #8
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    I had the same problem with a SIR9 and Thomson post. Tried light grease, carbon paste, stock seat clamp, Salsa Liplock clamp, Thomson clamp, new Thomson post, and 2 frames. Everything was within tolerance. Found a suggestion to clean everything and use climbers chalk or weight lifting chalk. All fixed. Good info here: Slipping seatpost- Mtbr.com
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  9. #9
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    Quote Originally Posted by jeff View Post
    I'll ask the obvious question. Are you sure it's the right size? The Soma specs show 27.2.
    Yes

  10. #10
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    I know it says Hope but I really don't like that quick release design. I would try it with a regular bolt on clamp and see what happens.

  11. #11
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    Quote Originally Posted by seat_boy View Post
    I've had some frames (Gunnar...) where I couldn't get the seat post to stay up. I ended up using a pop can shim to make up the difference.

    I just ran into the opposite problem tonight: I splurged on a Thomson seat post for my latest build, but it measures closer to 27.3 than 27.2. It won't go into my frame. And here I was all happy to be buying something made in the US... hmmm, like the Gunnar. This is disappointing.
    A buddy of mine told me last night that Thompson seat posts fit tight and he has used them himself.

  12. #12
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    Quote Originally Posted by J.B. Weld View Post
    I know it says Hope but I really don't like that quick release design. I would try it with a regular bolt on clamp and see what happens.
    The same friend told me last night also that they have seen slippage in the shop with QR. He suggested trying a bolt on as well. I am going to go out today and measure my tube and post with calipers and see what they read. How much tolerance is allowable? .001"? .002"?

  13. #13
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    Well here's a question...What a dilema. My post measure around 26.96 at the one point I am setting it for my correct height. In a lower place it measures around 27 even. My frame measures 27.2 on the money. I have noticed that it always slips till it hits an inch and a half or so lower then it stops. Will Race Face honor any kind of warranty even if I have cut it down to length? I may be screwed. I ordered from chain reaction. Maybe they will send me a new one? What is the odds that all of this model of seat posts will have this problem?

  14. #14
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    Quote Originally Posted by jeff View Post
    One of the two could be out of spec. Wouldn't be the first time.
    Spot on......

    I emailed Race Face and chain reaction. I guess since it is saturday I will have to wait a bit. I know CRC replys promptly but I am not sure Race Face is that prompt on returning emails. Technically I am sure Race Face will question my ability to read a micrometer and may ask me to mail the post to them and let them decide. Who knows. I would think the right thing to do would be to not argue and make a happy customer as many of their products as I have purchased. I mentioned to them that I am a fan of their products (I really am). We will see.

  15. #15
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    hopefully they replace the post free of charge. it may depend on what they consider "out of spec". clearly that is the problem though.

    i'll be interested to hear what happens.
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  16. #16
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    I am concerned when they hear that I cut it down they will try to say it voids the warranty if there is any. Not that cutting it hurt anything but still......

  17. #17
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    Is the post 29.96 all the way round at that point? Any chance it's a little oval?

  18. #18
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    Quote Originally Posted by OutLore View Post
    Is the post 29.96 all the way round at that point? Any chance it's a little oval?
    It's tough to tell but I am thinking it acts a little oval. If you settle the mic in it gives different readings off .02 mm so I suspect your correct. Also not sure if it's scored a bit ftom where it has been slipping

  19. #19
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    Clearly an unfortunate case of out of spec post. In the case that the post is to spec and still slipping, the one thing you can do is lightly grease the interface between the seat tube and the clamp. This allows the clamp to close more effectively around the seat tube. Works a treat.
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  20. #20
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    I had a similar problem with my Juice frame and Truvativ seatpost. I had the clamp oriented so that the slot on the clamp was opposite the slot in the frame's seat tube. I had torqued the bolt to 9Nm as per Surly's specs, and it always slipped down during my rides.

    I turned it 180 degrees so the two slots line up, torqued the bolt, and it has not slipped since. I did a little reseach and some suggested that setting the post with the slots opposite sides of the seat tube is wise for crabon stuff but to line up the slots for metals.

  21. #21
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    I'd have to look but I bought the slot was at the back? If that's the case my clamp is in the standard position with the opening facing the rear? Maybe I'm wrong on my frame guess I never paid any attention

  22. #22
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    unless you are using a carbon post, make the slot on your clamp line up with the slot on the frame. my experience is that you get a little more clamping power that way.

  23. #23
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    I gotta go with a bad seat QR.....the Hope QR is not great. I had one on a frame for a short period before I replaced it. No matter what I did, the post would slip during the ride.
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  24. #24
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    Quote Originally Posted by BENKD29 View Post
    hopefully they replace the post free of charge. it may depend on what they consider "out of spec". clearly that is the problem though.

    i'll be interested to hear what happens.
    Chain reaction was very helpful. I filled out a warranty form and included some pics of my seat post and within 1 hour I got an email saying they were sending me a replacement and to dispose of the old one.

  25. #25
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    nice, results! good for you. they did the right thing.
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    Stop asking how much it weighs and just go ride it.

  26. #26
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    I noticed the 2015 Turbine post has done away with the adjustment linkage with a new head design. Chain Reaction still has the 2014s in stock, like I have, so I imagine that is what I will get again. Anyone know why Race Face changed the design? I have heard a few complaints about creaking but 95% of the reviews are all good. Except for the slipping I love mine and it is quiet as a mouse lol.

  27. #27
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    - can also consider a double-bolt collar that bolts to the bike frame AND the post, giving you twice the grip in this situation........
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