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  1. #1
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    What to use to make the Brompton seat post slide smoother?

    I quite frequently see, in Brompton fold-speed competitions, people releasing the seatpost catch and having it slide down smoothly.

    Mine often 'catches' on something and requires a jiggle to get it free. Is there a safe/cheap/simple way to ensure a smooth up-down of the seatpost?

  2. #2
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    I have not experienced this problem, but back in the day when I lived in the midwest a common all-purpose lubricant was duck butter...

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    Senior Member smallwheeler's Avatar
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    Quote Originally Posted by DoubleDiamonDog View Post
    I have not experienced this problem, but back in the day when I lived in the midwest a common all-purpose lubricant was duck butter...
    good call!


  4. #4
    Senior Member bhkyte's Avatar
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    Keep it clean. Don't lubricate it, as it may slip, adjust plastic circular cam behind rear brake, replace plastic frame insert if worn. Not sure what else you can do.

    Tip avoid twisting the post generally as this tends to scratch it. Try pushing it backwards and forwards to open the frame up, then it should slide out easily.

    my mezzo seatpost fair better than my brompton one. Loosen the seatpost clamp and it actually fall in to the frame if really clean and we'll adjusted. Clamp design is higher, but under engineered as they have a tendency to crack.
    Last edited by bhkyte; 04-12-14 at 02:41 AM.
    Dual drive Mezzo (GOLD), Dual Drive Mezzo with bullbars (black), White Brompton thingy with Dahon Androes stem and bull bars. Birdie (old sytle) 7 speed. Downtube NS8. Birdie red.

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    Senior Member Ed in Toronto's Avatar
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    Are you pulling the lever on the seatpost clamp all the way back to the loose position, as far as possible?

    I find sometimes when I'm in a rush I don't fully release the seatpost clamp, and the post will jam or not go down smoothly.

  6. #6
    coprolite fietsbob's Avatar
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    sliding smoother = having it slip down as you ride the bike, then you will be back asking about how to fix that.


    you want to compete in the next London, Goodwood, Brompton World Championships speed fold contest?


    Its about skill ... practice , not parts ,,

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    PatronSaintOfDiscBrakes dynaryder's Avatar
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    Quote Originally Posted by keyven View Post
    I quite frequently see, in Brompton fold-speed competitions, people releasing the seatpost catch and having it slide down smoothly.
    Mine was like that when I picked it up from the shop. Slid down on me twice on the ride home. Adjusted the QR,and now I have to push it down,but it stays put when riding. Note,the guys in the folding comps aren't riding the bikes.

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    lowlife bottom feeder BassNotBass's Avatar
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    Either adjust the lever to find the sweet spot between allowing the post to glide smoothly in the unlocked position yet cinching it securely in the locked mode, reprofile the cam to allow a larger variance between unlocked and locked positions or replace the quick release lever with one that has a more aggressive cam profile... but of course the latter two options would slightly increase the amount of force you'd have to apply to lock the post.
    Last edited by BassNotBass; 04-12-14 at 08:40 PM.
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    Quote Originally Posted by fietsbob View Post
    sliding smoother = having it slip down as you ride the bike, then you will be back asking about how to fix that.


    you want to compete in the next London, Goodwood, Brompton World Championships speed fold contest?


    Its about skill ... practice , not parts ,,
    I was afraid of the post being TOO EASY to slide down, hence the caveat "safe/cheap/simple". I thought maybe there was a safe way to have my cake and eat it.

    Thanks anyways guys.

  10. #10
    lowlife bottom feeder BassNotBass's Avatar
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    Quote Originally Posted by keyven View Post
    I was afraid of the post being TOO EASY to slide down...
    Adjust the lever to the point between where the post slides easily and where it begins to bind in the fully unlocked position. That should be the sweet spot. That could be as little as 1/8 or even 1/16 turn of the lock nut opposite the lever.
    I plan on living forever... so far so good.

  11. #11
    Senior Member smallwheeler's Avatar
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    Quote Originally Posted by dynaryder View Post
    Mine was like that when I picked it up from the shop. Slid down on me twice on the ride home. Adjusted the QR,and now I have to push it down,but it stays put when riding. Note,the guys in the folding comps aren't riding the bikes.

    so, your idea is that in real, everyday use, the seat post clamp, in the course of normal usage, requires heavy clamping pressure which, over time deforms the seat tube enough to cause binding?

    interesting hypothesis.

    however, i beg to differ with you, kind sir.

    for you see, i have my own equally unscientific, subjective, and anecdotal experience i would like to convey (and then subsequently offer my own statistically irrelevant supposition).

    i have folded and unfolded and ridden my brompton™ bicycle practically everyday for the past 5 years. when i pop the QR, the seat post still drops down that tube like a.. duck-buttered sea bass giblet down the gullet of a half-starved albatross..

    as for my supposition regarding the sticky seat posts that you and the OP seem to be suffering from, for the purpose of clarity, i would offer this humble graphical representation:


    [genial, mirthful, charmingly irreverent]

  12. #12
    coprolite fietsbob's Avatar
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    I was afraid of the post being TOO EASY to slide down
    that was not the implication I was reading from your OP.


    Fwiw, when I got a 3rd hand Brompton Mk2, the slipping down while I rode was the issue ..

    A new,plastic frame shim was part of the cure, then I bought a new +6cm seatpost,

    then, from the LBS, I bought a second QR, one with its own band clamp.

    they are made to go on top of seat tubes of frames having the same diameter as the B seat post,
    so the band has a lip on the edge.

    I removed that lip so the band slides over the the seatpost upside down , and grips the seatpost itself.
    it sits atop the frame , when riding..


    Note,the guys in the folding comps aren't riding the bikes.
    But the race is a Le Mans start , the bikes are all folded up sitting in a grid on a field

    everyone runs to their bike , unfolds it, ... then they can start riding.
    Last edited by fietsbob; 04-13-14 at 09:37 AM.

  13. #13
    coprolite fietsbob's Avatar
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    Oh and RTFM !, published in 20 languages, it never states doing any lubricating of the seatpost .

    The Zen .. grasshopper .. https://brompton.zendesk.com/forums
    Last edited by fietsbob; 04-13-14 at 01:19 PM.

  14. #14
    PatronSaintOfDiscBrakes dynaryder's Avatar
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    Quote Originally Posted by smallwheeler View Post
    so, your idea is that in real, everyday use, the seat post clamp, in the course of normal usage, requires heavy clamping pressure which, over time deforms the seat tube enough to cause binding?
    Dude,what are you talking about? Please quote where I said that. My seatpost was slipping when I picked the bike up,so I correctly tensioned the QR,and now everything is as it should be. I have to give it a little push to get it all the way down because it bumps into that bumper thing on the back of the caliper.

    C'dale BBU('05 and '09)/Super Six/Hooligan8and 3,Kona Dew Deluxe,Novara Buzz/Safari,Surly Big Dummy,Marin Pt Reyes,Giant Defy 1,Schwinn DBX SuperSport/Qualifier,Brompton S6L,Dahon Speed Pro TT

  15. #15
    PatronSaintOfDiscBrakes dynaryder's Avatar
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    Quote Originally Posted by fietsbob View Post
    But the race is a Le Mans start , the bikes are all folded up sitting in a grid on a field

    everyone runs to their bike , unfolds it, ... then they can start riding.

    Folding comp ≠ bike race,they're separate.

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  16. #16
    Senior Member smallwheeler's Avatar
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    Quote Originally Posted by dynaryder View Post
    Dude,what are you talking about? Please quote where I said that. My seatpost was slipping when I picked the bike up,so I correctly tensioned the QR,and now everything is as it should be. I have to give it a little push to get it all the way down because it bumps into that bumper thing on the back of the caliper.
    i was just joking, man.

  17. #17
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    Quote Originally Posted by fietsbob View Post
    that was not the implication I was reading from your OP.


    Fwiw, when I got a 3rd hand Brompton Mk2, the slipping down while I rode was the issue ..

    A new,plastic frame shim was part of the cure, then I bought a new +6cm seatpost,

    then, from the LBS, I bought a second QR, one with its own band clamp.

    they are made to go on top of seat tubes of frames having the same diameter as the B seat post,
    so the band has a lip on the edge.

    I removed that lip so the band slides over the the seatpost upside down , and grips the seatpost itself.
    it sits atop the frame , when riding..
    As I already mentioned, I did say "safe way"... so it's not like I'm asking if I should grease it or whatever. One of the more annoying part of folding/unfolding is having the seatpost catch and needing to spend another few seconds (it adds up) to jiggle and free it.

    It would simply make the folding experience "better" if there was a simple way to get the post to slide down on its own, even if it does so very slowly.

  18. #18
    coprolite fietsbob's Avatar
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    im not there to watch, Im OK on my end with mine. this while wheel is out? or the last part of the fold?

    could just be the stop disc that holds the rear fold locked in that closed position you are hitting ..

    maybe its an owner OCD problem and the bike is as designed ..

    want to fly in experts from London on this? or a film crew to document your issue ..

    write the company , maybe they have a video they produced.

    maybe you would have been happier with a BF Tikit Fold , IDK ..

  19. #19
    lowlife bottom feeder BassNotBass's Avatar
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    Quote Originally Posted by dynaryder View Post
    ... I have to give it a little push to get it all the way down because it bumps into that bumper thing on the back of the caliper.
    That happens if the front wheel isn't locked with the rear swingarm or if the bumper isn't adjusted correctly.
    Last edited by BassNotBass; 04-14-14 at 08:23 AM.
    I plan on living forever... so far so good.

  20. #20
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    Quote Originally Posted by fietsbob View Post
    im not there to watch, Im OK on my end with mine. this while wheel is out? or the last part of the fold?

    could just be the stop disc that holds the rear fold locked in that closed position you are hitting ..

    maybe its an owner OCD problem and the bike is as designed ..

    want to fly in experts from London on this? or a film crew to document your issue ..

    write the company , maybe they have a video they produced.

    maybe you would have been happier with a BF Tikit Fold , IDK ..
    Can I say... all of the above?

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