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  1. #1
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    Fly 29er Ti seatpost slipping... How to fix?

    I switched to a Thomson seatpost on my Fly Ti (the original was too short for me), but it slips a good inch per ride. Any suggestions how to get it to stay put? I can't be the only guy with this problem.

    Thx,
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  2. #2
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    Quote Originally Posted by FishMan473 View Post
    I switched to a Thomson seatpost on my Fly Ti (the original was too short for me), but it slips a good inch per ride. Any suggestions how to get it to stay put? I can't be the only guy with this problem.

    Thx,
    Maybe some Tacx carbon paste. But I switched to a Thomson to fix this problem with an Easton EC90. Nothing I tried really worked, which is too bad since the EC90 rode really nicely.

    Between frame and post tolerances some will just slip. OTOH I think a while back some people had frames they had to send back to Bikes Direct for seat tubes that were a little too large...

  3. #3
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    How long back? My bike is a 2010. Its been a problem since day 1, but i have been on and off the bike due to injury. I put a carbon post in it at one point and I had to cinch it down so tight that I pinched the post and it broke at the seat collar during a race.
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  4. #4
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    Quote Originally Posted by FishMan473 View Post
    How long back? My bike is a 2010. Its been a problem since day 1, but i have been on and off the bike due to injury. I put a carbon post in it at one point and I had to cinch it down so tight that I pinched the post and it broke at the seat collar during a race.
    Mmmmmm...I think my 29er is a 2010, from the first run of them (late 2009 maybe?). Didn't have that problem on the 26er version, but it was running a larger 30.9mm size so it wasn't the same post.

    If two high end seat posts are slipping on you I'd say its a problem with the frame. Do you have a micrometer to measure it?

  5. #5
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    I recommend some chalk. I have a Thomson post and it was doing the same thing, but has not slipped since. I used plan old whiteboard chalk, I think it cost me $.50 at the drug store.

  6. #6
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    Quote Originally Posted by TXNavy View Post
    If two high end seat posts are slipping on you I'd say its a problem with the frame. Do you have a micrometer to measure it?
    I have a digital caliper, but I'm not sure how accurate it is. It measured the inner diameter of the seat tube at an average of 27.1 mm, but it measured the outside of my seatpost at an average of 27.05. Thomson is usually pretty accurate so I suspect my caliper is off.

    Also, I may have crimped the top of the seat tube slightly by cranking down seat collars really hard on it over the past couple of years. I wonder if the inner diameter is bigger an inch down in the tube.

    At the moment I have moved to a Salsa Liplock seat collar, with a stronger steel bolt than it came with and a washer under the bolt. This should be about as much binding force as you can get out of a seat collar. I'll see how it goes. I also reduced the amount of grease between the post and the seat tube to a bare minimum... perhaps that was lubing things up too well? Maybe I should switch to anti-sieze compound instead?

    Quote Originally Posted by elcaro1101 View Post
    I recommend some chalk. I have a Thomson post and it was doing the same thing, but has not slipped since. I used plan old whiteboard chalk, I think it cost me $.50 at the drug store.
    So you just grind up the chalk and use it in place of grease around the seat post?
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  7. #7
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    There probably arent any shims that thin but people have used pieces of a pop can as shims for this kind of problem... Might be worth a try and wont cost anything really.

  8. #8
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    Quote Originally Posted by FishMan473 View Post
    I have a digital caliper, but I'm not sure how accurate it is. It measured the inner diameter of the seat tube at an average of 27.1 mm, but it measured the outside of my seatpost at an average of 27.05. Thomson is usually pretty accurate so I suspect my caliper is off.

    Also, I may have crimped the top of the seat tube slightly by cranking down seat collars really hard on it over the past couple of years. I wonder if the inner diameter is bigger an inch down in the tube.

    At the moment I have moved to a Salsa Liplock seat collar, with a stronger steel bolt than it came with and a washer under the bolt. This should be about as much binding force as you can get out of a seat collar. I'll see how it goes. I also reduced the amount of grease between the post and the seat tube to a bare minimum... perhaps that was lubing things up too well? Maybe I should switch to anti-sieze compound instead?



    So you just grind up the chalk and use it in place of grease around the seat post?
    Nope, I just rubbed the chalk all over the post using the side of one of the pieces. No need to crush it, the machine lines in the post tore into the piece of chalk pretty well. I caked it on very liberally below and at the clamp point. Then cleaned up the post that was visible so it didn't look like a white chalky mess.

    I did not use grease as well, only the chalk.

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