Advertise on Bikeforums.net



User Tag List

Results 1 to 11 of 11
  1. #1
    Spinmeister
    Join Date
    Mar 2003
    Location
    Tempe,AZ
    My Bikes
    Scattante Carbon, Full Ultegra
    Posts
    623
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Slipping Seat Post

    On my Giant OCR 1 I began thinking the seat was sinking. After putting a piece of tape on the post then going for a long ride it had sunk quite a bit. Anyone else have this problem? How do I correct it? I have noticed I had to keep bumping up my seat for a while but I thought it was my imagination.
    "Training is what I’m doing while my opponents are sleeping in."- Bill Robertson

  2. #2
    Year-round cyclist
    Join Date
    Apr 2002
    Location
    Montréal (Québec)
    Posts
    3,023
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It is a new bike? Or one with an extra-long seatpost? There are a few possibilities and solutions:

    1. The seatpost is loose. Plausible if it's a new bike. All 27.2-mm seatposts are not created equal and all clamps are not created equal. If it's a new bike, see your LBS who might try a slightly larger seatpost.

    2. The binder bolt is bent, broken, etc. and not doing its job. THat sometimes happen, especially if you like a tight fit. I just replaced the binder collar and bolt on my 2.5-year-old bike.

    3. Bent seatpost or one with a "variable" diametre. If you sqeeze very hard the seatpost at the 10-cm mark, keep it there a good time, then raise it to 10.2 cm, is it possible to have a post sliding down to the place it was previously squeezed? Something might be measurable with a caliper.

    4. Too much grease on the post. Yes, I know everyone suggests to grease the post to prevent it from sticking in place. I actually prefer non-greasy ones.

    Regards,
    Michel Gagnon
    Montréal (Québec, Canada)

  3. #3
    Spinmeister
    Join Date
    Mar 2003
    Location
    Tempe,AZ
    My Bikes
    Scattante Carbon, Full Ultegra
    Posts
    623
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The bike is a 2001. I dont think the seat post is extra long. What are all those parts you described? Can I just pick them up at a LBS?
    "Training is what I’m doing while my opponents are sleeping in."- Bill Robertson

  4. #4
    The Red Lantern Rev.Chuck's Avatar
    Join Date
    Apr 2003
    Location
    Raleigh NC
    Posts
    5,967
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The most likely culprit is a stripped seat binder unless you have a carbon post and have greased it. They, carbon, should be grease free.
    With alloy posts, I prefer greased as I have had to remove several stuck posts by slotting them with a hack saw blade, tedious.
    Are you a registered member? Why not? click here to register. Its free, and only takes 27 seconds!
    Help out the forums, abide by our community guidelines.

    I am in the woods and I have gone crazy.

  5. #5
    www.mtbkanata.com mtbkanata's Avatar
    Join Date
    Nov 2002
    Location
    Kanata, Ontario, Canada
    Posts
    331
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If you have a qr on your seatpost collar, sometimes a 1/4 spin on that will help.. not sure if that's what you meant mgagnonlv, but that works for me all the time. I also just throw a round of electrical tape on my seat post right where it should be, that way I can see really easy if it has been slipping...

    Hope it works out for you!

    Joe
    Mountain Bike Videos/Photos Uploads: Click Here to Visit

  6. #6
    Year-round cyclist
    Join Date
    Apr 2002
    Location
    Montréal (Québec)
    Posts
    3,023
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I never had a quick-release seatpost collar, just the one with an M5 bolt.

    On my 2.5-year-old bike, I have succeded to snap the bolt once and to break the collar once. It definitely showed a crack near the bolt hole.


    BTW, I never had a stuck seatpost. Maybe I'm too finnicky with height adjustment, because I tend to readjust it twice a year (for Winter boots and Summer shoes respectively), and it then takes me a full month each time to fine tune the adjustment. I guess it prevents it from rusting in place.

    Regards,
    Michel Gagnon
    Montréal (Québec, Canada)

  7. #7
    Senior Member
    Join Date
    Feb 2001
    Location
    England
    Posts
    12,199
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Does copper anti-sieze work better than a std lithium grease for this purpose. ie is it less slippery ?

  8. #8
    The Red Lantern Rev.Chuck's Avatar
    Join Date
    Apr 2003
    Location
    Raleigh NC
    Posts
    5,967
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Antiseize is less slippery, its purpose is to keep stuff from bonding so it kind of sticky to stay on every thing. Unless you like finger prints in your wonderbread don't eat a sandwitch after using antiseize.
    Mgagnonlv, I usually have to do this when someone has purchased a used bike and needs it fitted to them.
    Are you a registered member? Why not? click here to register. Its free, and only takes 27 seconds!
    Help out the forums, abide by our community guidelines.

    I am in the woods and I have gone crazy.

  9. #9
    Senior Member chip's Avatar
    Join Date
    May 2003
    Posts
    314
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I know that I have had to get a file going and rough up the seat post a bit according to where you have it for your height?After roughing things up with sandpaper and a file it worked good

  10. #10
    Senior Member danr's Avatar
    Join Date
    Jul 2002
    Location
    Midwest USA
    My Bikes
    Trek 8000 (I'm testing a prototype).
    Posts
    590
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I would try one thing. Loosen up the seat clamp. When the seatpost is in the seattube, is there any freeplay? If so, it is possible that either the seatpost is the wrong size, the seatpost is so old that it has actually grinded to a smaller size (somewhat unlikely), and/or your frame has a manufacturing defect and the inner seattube diameter is too large. It doesn't take much.

    If the seatpost is snug and there is no freeplay, then I would assume that the seatclamp is not strong enough. I also like the suggestion of roughing up the seattube with a file or sandpaper.

    If you do have freeplay, one suggestion is to make a shim out of an aluminum can. They are easy to cut with a pair of scissors. I suggest rounding off the corners. I have an aluminum can shim on my seattube and my seatpost no longer slips.

    Also, if there is grease in your seattube, make sure that there is just enough grease to let the seattube slide in.
    Does the perfect bike really exist?

  11. #11
    Junior Member
    Join Date
    May 2002
    Posts
    19
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    For some time I pestered the fame manufaturer about my slipping seatpost. It was not the post. I could hardly believe what I found. One of the rails was broken on the saddle. I never even thougt to look for that

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •