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  1. #1
    meow, meow.
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    Thomson post, titanium frame, QR clamp: need a cure for slipping.

    Hi guys,

    I'm currently running a Thomson Elite 31.6 mm inline seatpost in a custom titanium frame, clamped with Hope QR clamp (new style). Hope clamps are known for generating lots of force, and I can say that I have to use most of it to clamp the post so that it doesn't slip. The effort is much more than what is necessary with aluminum frame and a smooth-surfaced aluminum post, same clamp.

    I specifically want a QR clamp, not a bolt-up one, because I adjust seatpost height often on this bike. I also would like to stay with Thomson posts (Masterpiece with Ti bolts upgrade is planned).

    To further reduce weight, I'm considering one of those KCNC SC10 QR clamps. They are about half the weight of a Hope clamp, but their levers are shorter, and their collars may not necessarily like being subjected to forces comparable with what Hope clamps develop. That is, a KCNC clamp can fail to work with my frame and post, if I leave them as they are.

    So, is there a nice way to make the inner surface of titanium seat tube grippier, where it presses against the post?
    26" faithful.

  2. #2
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    I had issues with thomson posts in two 575 frames with QR clamps. One was even a salsa, and no matter what I did they slipped. Unfortunately the only solution I found was a bolt-type clamp.
    Is the Joplin post too heavy to consider????

  3. #3
    meow, meow.
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    Yes, adjustable posts are heavy, and they don't have the range that I need on this bike. Well, maybe KS Cobra i900 comes close.. but it's about twice the weight of my current setup, much less the one with tuned Masterpiece. Convenience wise, QR clamp and a regular post are fine with this bike (it's a street trials training, do-all hardtail, which I also commute on, all in the same ride).
    26" faithful.

  4. #4
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    I hear you. My Thomson post has pinch marks due to being clamped too tightly using the QR. Kinda sucks but otherwise it slipped.

  5. #5
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    Use...

    carbon assembly paste instead of normal grease on the post-this will stop any slipping. Degrease the inside of the seat tube first.
    Curious, though why you want light weight and to be able to drop your post? Stopping at the top of a climb to drop your post for a descent will take longer than the time saved by having a lightweight seatpost. Make up your mind: you want a light bike to maximize speed and you do not stop to drop your seat, or get some burly components, drop your seat whenever you want to.
    Fast riders run bolted seatpost collars and do not stop to drop the seat.

  6. #6
    meow, meow.
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    I need height adjustment not for switching between climbs and descents. In fact, as we don't have real mountains here, I climb everything in standing position. Where adjustment comes in handy, is switching between commute mode (5 to 7 inches of exposed post), micro DH mode (3 to 5 inches of post) and play/training mode (0 to 2 inches of post, sometimes more).

    I didn't mean this bike to be fast off road, it has short wheelbase, somewhat sharp steering and low gearing, which is all I need for trials and street. The reason why I aim for light weight is not for speed and acceleration, but that a light bike is easier to jump, steer in the air, and I can train longer, because it takes longer to exhaust. Pure trials bikes are even lighter than mine, all for the same reasons.

    And I never put any grease in there to begin with. I may resort to carbon assembly paste, but I don't feel it's a nice workaround for frequent QR height adjustments.
    26" faithful.

  7. #7
    Te mortuo heres tibi sim?
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    chalk dust. no grease, obviously. it's not as if you have to worry about the frame or post corroding on you, at least during it's useable lifetime. it'll help the too dissimilar materials from bonding if you leave them sitting too long as well.
    Florence Nightingale's Stormtrooper

  8. #8
    meow, meow.
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    chalk dust, yes.. sounds better than carbon assembly paste. )
    I'll give it a try.

    I've been thinking about a kind of glue coating on titanium. That is, coat lightly and let dry. Then install post. If the glue holds on to titanium, it would create lots of friction.
    26" faithful.

  9. #9
    Don't be hasty.
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    The KCNC clamp is still a good idea though, I've probably torqued mine way too much and it holds up great.

  10. #10
    meow, meow.
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    scrublover's chalk dust proposition actually got me thinking.

    I'm going to google for a metal adhesive glue that dries up so that it's no longer sticky. Degrease inside of seat tube, coat with thin layer of glue, apply some chalk dust, then wait until it all dries. This is perhaps similar to how organic disc brake pads work.
    26" faithful.

  11. #11
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    Why not a bolt on? If you want to adjust, don't you carry an allen key anyway?

    Thomson Masterpiece + KCNC clamp + ti frame -> no slippage here..

  12. #12
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    Quote Originally Posted by Curmy
    Why not a bolt on? If you want to adjust, don't you carry an allen key anyway?
    Yes, I do carry the keys, it's just that I'm usually too lazy to bother with the backpack.
    Sometimes I carry a multitool in a pocket, but it hurts to crash on it.
    That's why I put QR clamp on there, - especially so as to have no excuse for not adjusting saddle height to suit current activity.
    26" faithful.

  13. #13
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    I am very curious about this titanium street/trials bike, mind posting a picture?

  14. #14
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    I had the same problem, ti frame and slipping Thomson post

    I tried the carbon anti seize paste...did not work so my LBS guy had a tool called a "knurling tool" and it finally solved the problem

    the knurling tool makes small micro ridges in the post and gives a roughed up surface for the post to grab on the ti seat tube ....

    you might want to call around and maybe one of your local bike shops might have the tool

  15. #15
    meow, meow.
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    nwd_26, a photo has been buried somewhere in the 1x9 thread, mid-summer this year. I'll try to find it.. the photo is ugly, however - I'm even crappier photographer than a rider.

    doco, failing that glue and chalk dust idea, loos like knurling the post would remain my only option.. I'll make sure I really tried with the glue first. )

    PS
    My post in the 1x9 thread.
    It has not yet been ridden when I took that photo, notice the clean tires and how high the saddle is. )

    The bike is somewhat old school spirit, it seems. I learned this accidentally when I first watched the Dirty Tricks and Cunning Stunts video, this spring. Much to my surprise, in the video they were riding bikes very similar to this one, that I had started building back then, without yet knowing the similarity.

    I changed pedals to NS Aerials, and I find them to be much better shape. Lighter, too.
    The front brake is now Hope Tech X2, and it's very good.
    Last edited by J. Random Psycho; 10-17-2009 at 08:48 PM.
    26" faithful.

  16. #16
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    Quote Originally Posted by J. Random Psycho
    That's why I put QR clamp on there, - especially so as to have no excuse for not adjusting saddle height to suit current activity.
    I do not adjust on my light hardtail, seems t work ok, and I got into the hype and installed adjustable seatpost with remote on my burly bike and I should admit that hype is every bit justified.

    They should come up with sub 400g adjustable seatpost...

  17. #17
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    Psyco, I think your only option is knurling.You also may want to check out the Mortop QR seatpost clamp.Its lighter than the KCNC & I had to put excess load on it with no issues until I started using carbon paste on my carbon post to carbon frame.

  18. #18
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    xc71, thanks for that Mortop info. It's an interesting piece. Looks nicer than KCNC, too.

    From what I can see, it doesn't use a curved brass washer to facilitate easier sliding of the lever? That means aluminum on aluminum friction - did you have to put a little grease in there?


    BTW, I just noticed some funny flat pedals on that ebay store. Seals on the new Xpedo ones look very similar to those on my NS Aerials. Hmmm...
    26" faithful.

  19. #19
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    Yes, alum on alum.I would put grease on it.Also mine came in at 19.5 grams, very happy with it other than the color.Online the blue looks like a deep royal blue - viewed on 3 different computers.When mine showed up its more like a torquoise.

  20. #20
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    You might find greasing the inside face of the hope clamp before fitting it to the frame will help. The idea behind this is that it helps the band of the clamp to pull round the top of your seat-tube so you get a nice even clamping force around the post, rather than just a pinch on one side. Does that make sense? Grease the inside of your clamp then put it back on the frame.

    Also a little grease on the cam part of the clamp will allow you to apply a bit more pressure when you close the clamp because of reduced friction.

    Before you go putting anything weird in your frame make sure the frame and post are clean and free from grease or any oily residues. See if greasing the clamp and having a clean post and seat-tube do the trick. Let me know how it is.

  21. #21
    fnar fnar brrraaaaap
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    I'd try a salsa QR

  22. #22
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    ilostmypassword, why, the Hope clamp works well enough. And it weighs about the same.

    Quote Originally Posted by mikesnowdon
    You might find greasing the inside face of the hope clamp before fitting it to the frame will help. The idea behind this is that it helps the band of the clamp to pull round the top of your seat-tube so you get a nice even clamping force around the post, rather than just a pinch on one side. Does that make sense? Grease the inside of your clamp then put it back on the frame.

    Also a little grease on the cam part of the clamp will allow you to apply a bit more pressure when you close the clamp because of reduced friction.

    Before you go putting anything weird in your frame make sure the frame and post are clean and free from grease or any oily residues. See if greasing the clamp and having a clean post and seat-tube do the trick. Let me know how it is.
    Yes, I thought about greasing between the clamp and the frame back when I put the bike together. However, it turned out that anodized aluminum against titanium contact is slippery enough. In the past, I certainly had this experience, when you feel it would be necessary to grease; this was with aluminum frames and posts, and generic no-name QR clamps (those with plastic piece in them). In one instance, merely replacing a no-name clamp with Hope QR clamp cured that perfectly without greasing anything.

    I also thought about greasing the cam yesterday, when I wrote that note about the Mortop clamp. And then I imagined the mess that would result. )

    I heard about the glue trick from XC racer guys who run superlight carbon seatposts (like Schmolke and Garbaruk posts - I saw one of the latter personally, and it's scary light. The guy takes podiums, however). What they do is put some drops of superglue on the post, and let it cure. No chalk dust or anything. Perhaps this only applies to carbon posts, I don't yet know. But I think it's safe to try, because superglue can be removed with acetone.

    What I'm going to do is get one of those Mordor QR clamps and first try greasing between clamp and tube. Plan B would be to actually try the superglue. Plan C, to concoct something with chalk dust. I'll report back here with results.
    26" faithful.

  23. #23
    fnar fnar brrraaaaap
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    Quote Originally Posted by J. Random Psycho
    ilostmypassword, why, the Hope clamp works well enough. And it weighs about the same.
    .
    Weight maybe- but the clamping action is far superior on the salsa. It does not clamp by "pinching" rather by "clamping equally". It has to do with the actual mechanism.

    Worth a try for just a few $

  24. #24
    meow, meow.
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    Quote Originally Posted by ilostmypassword
    Weight maybe- but the clamping action is far superior on the salsa. It does not clamp by "pinching" rather by "clamping equally". It has to do with the actual mechanism.
    Hmmm... from the look of it, it only differs from Hope clamp in that the lever is bigger, and there is no brass piece. I thought that its famous clamping strength results from sheer size of the lever?
    26" faithful.

  25. #25
    fnar fnar brrraaaaap
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    Quote Originally Posted by J. Random Psycho
    Hmmm... from the look of it, it only differs from Hope clamp in that the lever is bigger, and there is no brass piece. I thought that its famous clamping strength results from sheer size of the lever?
    I've used both and had better results with the Salsa - so that's all i can say. Good luck!

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