Slipping seatpost, how to stop ?

Discussion in 'Mountain Bikes' started by Trevor S, May 25, 2003.

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  1. Trevor S

    Trevor S Guest

    I have a Merida Matts Special '03, the seat post slips down oh so slowly over time (say in 20km I
    woudl have to stop to adjust it once). I don't want to fix it permanetly at one height, as I have
    two ride heights I use, a shorter one for downhill and rough X/C and a higher one for transport
    sections and milder X/C.

    I thought I must be to fat :) but my my skinny ass'd mate has the same bike and his slips as well :(

    It's an Al post and the frame is Al.

    Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    different metals ?.

    Ideas ? Gnurling of somesort ?

    Trevor S
     
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  2. David Kunz

    David Kunz Guest

    Trevor S wrote:
    > I have a Merida Matts Special '03, the seat post slips down oh so slowly over time (say in 20km I
    > woudl have to stop to adjust it once). I don't want to fix it permanetly at one height, as I have
    > two ride heights I use, a shorter one for downhill and rough X/C and a higher one for transport
    > sections and milder X/C.
    >
    > I thought I must be to fat :) but my my skinny ass'd mate has the same bike and his slips
    > as well :(
    >
    > It's an Al post and the frame is Al.
    >
    > Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    > different metals ?.
    >
    > Ideas ? Gnurling of somesort ?
    >
    > Trevor S

    1. Make sure that the post is the right size. I'd check the bike to make sure that it's really the
    size that they say it is also. It only takes a fraction of a mm for this to happen.

    2. The clamp has a lip to keep it at the top of the frame. This lip can't touch the seat post or the
    clamp won't tighten properly -- it won't clamp the frame, just the post. Make sure that this
    isn't happening.

    3. I used a clamp on the seat post to give extra hold on a Tompson that had that problem -- until I
    noticed that the reason for the problem was that it had cracked and had collapsed slightly at the
    clamping point! But, I started with a radiator hose clamp and then I found a clamp to add a water
    bottle to the seat post that worked just as well and looked A LOT better :).

    4. Sounds like you might be using a quick clamp. Don't. Get a clamp that tightens with a hex bolt
    and tighten it! Salsa clamps work well for me -- YMMV.

    I you skip the grease and start getting "bottom bracket" squeeking -- it's probably the seat post
    :). Mine needs LOTS of grease and needs to be refreshed on occasion.

    David
     
  3. I would have thought the problem is with the clamp, not the post, unless the post is the wrong size.
    Either way I'd be asking Merida to solve the problem and by ask I mean "tell"

    "Trevor S" <[email protected]> wrote in message news:[email protected]... I have
    a Merida Matts Special '03, the seat post slips down oh so slowly over time (say in 20km I woudl
    have to stop to adjust it once). I don't want to fix it permanetly at one height, as I have two ride
    heights I use, a shorter one for downhill and rough X/C and a higher one for transport sections and
    milder X/C.

    I thought I must be to fat :) but my my skinny ass'd mate has the same bike and his slips as well :(

    It's an Al post and the frame is Al.

    Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    different metals ?.

    Ideas ? Gnurling of somesort ?

    Trevor S
     
  4. Penny S.

    Penny S. Guest

    > "Trevor S" <[email protected]> wrote in message news:[email protected]... I
    > have a Merida Matts Special '03, the seat post slips down oh so slowly over time (say in 20km I
    > woudl have to stop to adjust it once). I don't want to fix it permanetly at one height, as I have
    > two ride heights I use, a shorter one for downhill and rough X/C and a higher one for transport
    > sections and milder X/C.
    >
    > I thought I must be to fat :) but my my skinny ass'd mate has the same bike and his slips
    > as well :(
    >
    > It's an Al post and the frame is Al.
    >
    > Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    > different metals ?.
    >
    > Ideas ? Gnurling of somesort ?
    >
    > Trevor S

    have LBS checck the diameters of all tubes involved. There are a lot of shims out there, even very
    thin ones that might help your problem.

    Penny
     
  5. x

    x Guest

    RE/
    >I would have thought the problem is with the clamp, not the post, unless the post is the
    >wrong size.

    Don't let the previous posters advice about not using a lever clamp slip by.

    When I first read the same advice some weeks ago, a little voice said "Geeze, how can that be...?
    Must be bad advice..".

    My seatpost was doing what it sounds like your's is doing: just slowly slipping down - maybe a
    quarter-inch in an hour's riding no matter how tight I made the QR lever.

    Finally, I said "Whyyyyy not?" and replaced my QR clamp with a regular hex-key clamp and the
    slipping immediately ceased.

    The clamp looks exactly the same as the QR clamp except for the binder bolt. I never would have
    thought that there could be that much diff in clamping force between the QR lever and a plain old
    allen key bolt. I trolled this idea in the 'disk brakes can make the front wheel pop out' thread,
    but nobody bit.
    -----------------------
    PeteCresswell
     
  6. Djarvinen

    Djarvinen Guest

    Trevor S <[email protected]> wrote in message news:<[email protected]>...
    >
    > Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    > different metals ?.

    Actually, oxidation is more likely when you have two different metals rather than one. That's why
    components are sometimes coated with a similar material such as zinc dust.

    DJ
     
  7. Klydesdale

    Klydesdale Guest

    "ClydesdaleMTB" <[email protected]> wrote in message news:[email protected]...
    >
    >
    > http://www.surlybikes.com/parts/constrictor.htm
    >
    > http://www.lhthomson.com/seatpost.asp
    >
    >

    Not a cure-all in my experience. In fact, quite the opposite. A Thomson seatpost that was to the low
    side of their design and manufacturing tolerances worsened the slipping woes I had on two different
    steel frames. I also suspect it, coupled along with the beefier clamp I tried in an effort to keep
    it from slipping, contributed to one of those frames cracking at the clamp relief cutout.
     
  8. Bo Lind

    Bo Lind Guest

    Trevor S wrote:

    <ka-snip!>

    I store my bike hanging on a custom titanium CNC-milled ├╝ber rack[*] that my car-tunin' arc-welding
    buddy Lars made for me for a mere bottle of Laphroigh. This requires me to raise and lower the
    saddle everytime I put it on the wall and everytime I take it down[**]. To facilitate this, I
    invested in a QR seat clamp, but I too experience saddle slippage woes. Any good ideas for a guy who
    need to "fiddle with his post" before and after every ride?

    Bo

    [*] OK, so it's just stainless steel, but custom none the less... :) [**] Here's the concept
    explained in greater detail: The bike is resting against the wall with the tires and the left pedal.
    Now imagine elevating the pedal until both the saddle and left handlebar touches the ceiling. There
    you go, space saving bike storage much needed when you live on 12 m^2 (~120 sqf for you USians.)
     
  9. Slacker

    Slacker Guest

    <snip>

    > Finally, I said "Whyyyyy not?" and replaced my QR clamp with a regular hex-key clamp and the
    > slipping immediately ceased.
    >
    > The clamp looks exactly the same as the QR clamp except for the binder bolt. I never would have
    > thought that there could be that much diff in clamping force between the QR lever and a plain old
    > allen key bolt. I trolled this idea in the 'disk brakes can make the front wheel pop out' thread,
    > but nobody bit.
    > -----------------------
    > PeteCresswell

    Can you still use a hex bolt type with a frame [ http://www.pbase.com/image/3861780 ] that doesn't
    have a replaceable seat post collar?

    I've been wanting to get rid of my QR forever.
    --
    Slacker
     
  10. John Harlow

    John Harlow Guest

    Has anyone ever tried knurling or grooving seatposts and the inside of downtubes?
     
  11. Technician

    Technician Guest

    In article <[email protected].dfncis.de>, slacker7 @sbcglobal.net says...
    > <snip>
    >
    > > Finally, I said "Whyyyyy not?" and replaced my QR clamp with a regular hex-key clamp and the
    > > slipping immediately ceased.
    > >
    > > The clamp looks exactly the same as the QR clamp except for the binder bolt. I never would have
    > > thought that there could be that much diff in clamping force between the QR lever and a plain
    > > old allen key bolt. I trolled this idea in the 'disk brakes can make the front wheel pop out'
    > > thread, but nobody bit.
    > > -----------------------
    > > PeteCresswell
    >
    >
    > Can you still use a hex bolt type with a frame [ http://www.pbase.com/image/3861780 ] that doesn't
    > have a replaceable seat post collar?
    >
    > I've been wanting to get rid of my QR forever.
    > --
    > Slacker
    >
    >
    >

    ha, you just wanted to brag indiscreetly about your pair of I-drives. ;-)
    --
    ~Travis

    travis57 at megalink dot net http://www.megalink.net/~farmers/
     
  12. Bb

    Bb Guest

    On Sun, 25 May 2003 20:57:08 +0200, Bo Lind wrote:

    > Any good ideas for a guy who need to "fiddle with his post" before and after every ride?

    I hear it makes you go blind if you do it too much.

    --
    -BB- To reply to me, drop the attitude (from my e-mail address, at least)
     
  13. Slacker

    Slacker Guest

    > ha, you just wanted to brag indiscreetly about your pair of I-drives. ;-)
    > --
    > ~Travis

    Uh, that would be a confession not a brag.
    --
    Slacker
     
  14. Technician

    Technician Guest

    In article <[email protected]>, slacker7 @sbcglobal.net says...
    > > ha, you just wanted to brag indiscreetly about your pair of I-drives. ;-)
    > > --
    > > ~Travis
    >
    >
    > Uh, that would be a confession not a brag.
    > --
    > Slacker
    >
    >
    >

    he he, i could say something, but i'll leave it as is.
    --
    ~Travis

    travis57 at megalink dot net http://www.megalink.net/~farmers/
     
  15. Trevor S

    Trevor S Guest

    [email protected] (djarvinen) wrote in news:[email protected]:

    > Trevor S <[email protected]> wrote in message news:<[email protected]>...
    >>
    >> Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    >> different metals ?.
    >
    > Actually, oxidation is more likely when you have two different metals rather than one.

    That's what I meant to say, it sounds a little odd when I re-read it :) ... The post and the frame
    are Al therefore oxidiation should not be a problem, someone else did mention removing the grease
    might allow creaks to start.

    Trevor S
     
  16. Trevor S

    Trevor S Guest

    "(Pete Cresswell)" <[email protected]> wrote in news:[email protected]:

    > RE/
    >>I would have thought the problem is with the clamp, not the post, unless the post is the
    >>wrong size.
    >
    > Don't let the previous posters advice about not using a lever clamp slip by.
    >
    > When I first read the same advice some weeks ago, a little voice said "Geeze, how can that be...?
    > Must be bad advice..".
    >
    > My seatpost was doing what it sounds like your's is doing: just slowly slipping down - maybe a
    > quarter-inch in an hour's riding no matter how tight I made the QR lever.
    >
    > Finally, I said "Whyyyyy not?" and replaced my QR clamp with a regular hex-key clamp and the
    > slipping immediately ceased.

    Thanks for the tips but QR obviously does work as I have a QR on my Giant and it has not slipped in
    4 years, on my Merida it does all the time though
    :(

    Trevor S
     
  17. Trevor S wrote:

    > I have a Merida Matts Special '03, the seat post slips down oh so slowly over time (say in 20km I
    > woudl have to stop to adjust it once). I don't want to fix it permanetly at one height, as I have
    > two ride heights I use, a shorter one for downhill and rough X/C and a higher one for transport
    > sections and milder X/C.
    >
    > I thought I must be to fat :) but my my skinny ass'd mate has the same bike and his slips
    > as well :(
    >
    > It's an Al post and the frame is Al.
    >
    > Should I maybe ditch the post lube, as there should not be a problem with oxidation with two
    > different metals ?.
    >
    > Ideas ? Gnurling of somesort ?
    >
    > Trevor S

    after you taken all the advice already posted. you can use a center punch to put a dozen or so
    'pock' marks around the post just below where it fits into the tube. it'll solve the prob.
     
  18. x

    x Guest

    RE/
    >Thanks for the tips but QR obviously does work as I have a QR on my Giant and it has not slipped in
    >4 years, on my Merida it does all the time though

    I had one on my Isis and it worked for a couple years.

    Now it doesn't.

    Go figure...
    -----------------------
    PeteCresswell
     
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