# Brommie - slipping seat post



## Yellow Fang (17 Sep 2015)

I have a problem with my Brompton. The seat post keeps slipping. By the time I've cycled the three miles from the station to work, it has slipped about two inches. However, if I tighten the nut sufficiently to stop the slippage, I cannot fold and unfold the bike. Does this indicate some difficult-to-fix problem in the seat post collar? It looks like I will have to spend some time and money replacing many of the parts. If I cannot fix the seat post problem myself then I might just ask the bike shop to do it all.


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## TheDoctor (18 Sep 2015)

Have you tried cleaning the seat post?


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## shouldbeinbed (18 Sep 2015)

^ +1 and inside the seat tube.


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## Yellow Fang (18 Sep 2015)

No, I'll give that a try.


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## TheDoctor (18 Sep 2015)

It worked on mine


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## Kell (21 Sep 2015)

Mine slipped when the bike was new - I think it might have been too clean.

I did read about people putting another seat clamp on the seat post itself, and clamping it tight to stop the seat post from going in to the seat tube, but I just tried scuffing the seat post with some sand paper.

This completely cured it for me.

Though it does mean your shiny looks a little less shiny.


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## Kell (21 Sep 2015)

It would take a little longer, but probably no more than having to undo two on telescopic seat posts.

I think the idea is that you add a QR seat clamp. so you undo two and the seat post slips through it.

Seemed a bit of a faff, but it was next on my list if the sandpaper trick didn't work.


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## Yellow Fang (19 Oct 2015)

I don't really like the idea of sandpapering my seat post. I could use an extra QR clamp, but I don't really like that idea either. I have seen posts on other site which suggested friction paste. Has anyone heard of this?


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## Kell (20 Oct 2015)

Are you still suffering?


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## Yellow Fang (20 Oct 2015)

Kell said:


> Are you still suffering?



Yes, although I have been replacing lots of parts on it recently. The seat-post problem is the last thing.


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## Bromptonaut (20 Oct 2015)

The clamp itself can wear over time due to the locking cam inside losing its profile. Replacements are available.


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## Kell (20 Oct 2015)

well. mine's not been a problem at all since the sandpapering...


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## jay clock (20 Oct 2015)

I had the same problem on day 1. Solved by tightening the hex nut. Are you sure you have tried this properly?


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## Yellow Fang (20 Oct 2015)

jay clock said:


> I had the same problem on day 1. Solved by tightening the hex nut. Are you sure you have tried this properly?



I have tightened it and loosened it several times. If you tighten too much then you cannot open the clamp.


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## jay clock (20 Oct 2015)

Yellow Fang said:


> I have tightened it and loosened it several times. If you tighten too much then you cannot open the clamp.


go back to the shop


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## Yellow Fang (21 Oct 2015)

Took it into the shop at lunchtime. First, he said the clamp only appeared to be tight because the bolt needed oil. After lubricating it, he said that actually the cam was worn down on the clamp, so it was not actually applying much pressure on the post. My Brommie is an older model, with the older version of clamp. However, he had a stash of 2nd hand clamps, fitted one, and charged me £2.


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## Milkfloat (21 Oct 2015)

Yellow Fang said:


> charged me £2.



And people say Brommie ownership is expensive.


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## Kell (21 Oct 2015)

jay clock said:


> I had the same problem on day 1. Solved by tightening the hex nut. Are you sure you have tried this properly?



I tried this with mine and it helped, but didn't prevent it from happening.

I've since loosened it after scuffing the post with sandpaper as I've read it can distort the frame if too tight. and I've had no bother.


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## Yellow Fang (28 Oct 2015)

No, I don't think the new clamp sorted it. Next stop: sanding the post, although I don't like the idea of that. Then a second seat post clamp, then friction paste.


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## srw (29 Oct 2015)

I find that over time the clamp gradually gets less effective at supporting my prodigious weight. Tightening the nut _slightly_ (less than a quarter of a turn) is all that's required - I vaguely remember reading somewhere that over-tightening the nut will wreck a Brompton clamp.

To the OP - find a position where the clamp slips, and then try some very small adjustments.


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## Yellow Fang (2 Jan 2016)

Still having problems. Bought a QR 31.8mm seat clamp, but that did not work because even loose, it would not slip down the post very easily. Maybe I should get the next size up. I notice you can buy replacement seatpost sleaves and the rubberized glue, but it looks like a tricky job to get the old one out. I notice the sleeve is thinner one side than the other. I wonder whether it is a bit worn. The other thing I am considering is carbon friction paste.


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## Yellow Fang (2 Jan 2016)

User said:


> Have you contacted Brompton themselves?



No, I have not done that.


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## Yellow Fang (2 Jan 2016)

User said:


> Why not try it? After all, they may have experience of your problem and a solution to hand.



I was not aware they had a support site. I have emailed them for advice. Cheers.


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## chris folder (3 Jan 2016)

Hi the rubber sleeve inside bike where seat post slides into wears after time. Some dealers take it out and re new it they use heat to remove old sleeve.


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## TheDoctor (3 Jan 2016)

The sleeve is plastic. Nylon IIRC. Not rubber.
It's held in with a rubbery glue.

@mickle is a Brompton trained mechanic, hopefully he'll drop by soon...


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## chris folder (3 Jan 2016)

Hi the rubber/plastic sleeve inside bike wears and when it do the seat post can slip some brompton dealers remove the sleeve with heat to put a new sleeve in. I would check that area on your bike


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## T4tomo (3 Jan 2016)

chris folder said:


> Hi the rubber sleeve inside bike where seat post slides into wears after time. Some dealers take it out and re new it they use heat to remove old sleeve.





TheDoctor said:


> The sleeve is plastic. Nylon IIRC. Not rubber.
> It's held in with a rubbery glue.
> 
> @mickle is a Brompton trained mechanic, hopefully he'll drop by soon...





chris folder said:


> Hi the rubber/plastic sleeve inside bike wears and when it do the seat post can slip some brompton dealers remove the sleeve with heat to put a new sleeve in. I would check that area on your bike




My (Ti) post slips down a little occasionally under heavy breaking, and occasionally slips round if I knock it with my thigh when out of the saddle, but I can thump it back straight on the move. i just tighten to clamp bolt occasionally if it's giving me a problem.


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## StuartG (4 Jan 2016)

My approach, probably with the aid of the dealer, is simply exchange seat posts with another Brommie. Does the problem move or stay?
That tells you whether it is the seatpost or the tube. Saves wasting time on trying to fix the wrong thing.


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## Yellow Fang (7 Jan 2016)

Brompton support recommended I take it into the bike shop and get the seatpost sleeve replaced, so that's what I did. I will soon find out if that fixed it.


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## chris folder (7 Jan 2016)

Hi good idea should be ok after new sleeve Fitted. if you keep tightening up clamp on post to stop slippage when rubber/plastic sleeve is worn the frame could develope a crack around seat post clamp area that can happen on old bikes where sleeve never replaced. A crack can appear


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## KeithCycles (12 Jan 2016)

Take it back to the dealer, they always fix mine for free


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## T4tomo (18 Jan 2016)

Did it f


Yellow Fang said:


> Brompton support recommended I take it into the bike shop and get the seatpost sleeve replaced, so that's what I did. I will soon find out if that fixed it.



Did it fix it? And if so how much did it cost?


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## Yellow Fang (18 Jan 2016)

It seems a lot better. It cost £24.


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## Sara_H (18 Jan 2016)

I had the same problem when my Brompton was new but it seems to have sorted itself out.


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## Yellow Fang (4 Mar 2016)

Replacing the seat post shim has fixed it. I have not noticed the problem much since.


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## chris folder (4 Mar 2016)

Hi I told you it was that all sorted now then. They do wear out you can buy the shim and glue to do it yourself if like


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