Seat Post Slowly Goes Down.

jedi_master
jedi_master Posts: 888
edited October 2014 in MTB workshop & tech
The seat post on my brothers bike keeps slipping down slowly, now matter how tight it is done up. The frame is a Piglet 2, Truvativ T20 and Cromag QR seat clamp. Does a steel frame need a lot of pressure to hold it? or would some of that carbon grip paste help.

Any suggestions?

If you undo the clamp the seat post drops straight down, where on my frame, even undone you still have to give it a little push to go down, it doesn't just drop as soon as it's undone.

Comments

  • ps4customgamer
    ps4customgamer Posts: 34
    The seatpost obviously doesnt sit in the frame as it should and one of the parts isnt correct, either the seatpost, frame or clamp.
    I'd use a digital micrometer to check the sizes.
  • cooldad
    cooldad Posts: 32,599
    Sounds like the wrong size seatpost. Is it a new problem or not?
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  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Take everything apart and clean thoroughly. Reassemble with just a light smear of assembly paste.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • iwilldoit
    iwilldoit Posts: 710
    Another thing to try if the post isn't the wrong size is take the QR off give that a good clean and lube, my Specialised seatpost used to go down very slowly while riding the bike and all it was the QR was on the dry side.
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  • The Rookie
    The Rookie Posts: 27,812
    Id agree with that, dirt in the bushings means a much higher level load for the same clamping load, making the lever feel like its really tight but in reality having poor clamping.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • veronese68
    veronese68 Posts: 27,811
    My Kinesis used to do that, even though the seat post was definitely the right size. Turned out the clamp was utterly useless. Changed the clamp and not had a problem since.
    Kinesis Pro6
    Marin Nail Trail
    Cotic Solaris
  • The Rookie
    The Rookie Posts: 27,812
    What clamp? A Hope?
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • veronese68
    veronese68 Posts: 27,811
    The Rookie wrote:
    What clamp? A Hope?
    Got a Thompson one with a screw, then wanted a quick release as doing more off road and got a Salsa. Both have been very good. The original was a Kinesis branded one, utterly useless. I know 2 others with a Crosslight that have changed the clamp.
    Kinesis Pro6
    Marin Nail Trail
    Cotic Solaris
  • cycleclinic
    cycleclinic Posts: 6,865
    I had this problem on my new 29er I am using the correct post but used a light weight seat post clamp. Big mistake but assembly paste (the stuff for carbon parts) cured the problem. So there is a cheap solution. changing the clamp would be my other solution but the paste is cheaper.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • revmatt
    revmatt Posts: 75
    This happened to me - correct seat post & clamp etc just poor quality.

    Bought a Thompson clamp and some carbon non slip paste and have had no problems since.

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