Seat slipping

[icowden]

But the one thing my bike excels at is folding much faster than a brompton!! Those seconds could kill my smug satisfaction rating...

 

[chriscross1966]

Replace whichever of the seatpost or seatpost tube liner is the sacrificial part, on a Brompton thats the liner. Not an expensive part if you can handle the fitting yourself.

 

[Slioch]

@icowden
I think I've resolved the issues with my seatpost slipping.

This time I "properly" degreased the seat post and the inside of the seat tube by using a degreasing bike cleaning spray bought from Wilko's. Previously I had tried to degrease using hot water and washing up liquid, but this clearly was inadequate in removing all traces of grease.

I then applied some carbon gripper paste bought off Ebay here.

I've been out for a couple of short rides and been deliberately bouncing the bike over potholes etc, but so far the seatpost hasn't budged at all.

Fingers crossed

 

[chriscross1966]

Gripper paste causes accelerated wear of the post liner in my experience, it just needs to be clean and within tolerances.

 

[SkipdiverJohn]

I would not drill through the post because of the consequences of any failure.

I'd drill the seatpost and put a pin or bolt through it. I'm not precious about workhorse machinery; it's there to do a job and if drilling solved the problem, I'd drill! Drilled holes don't normally propagate cracks either, it's stress-raisers like hacksaw cuts or filed grooves that can start off a failure.

 

[Venod]

Fitting a jubilee clip is a good suggestion, but the problem I'd have is that I need to be able to drop the seatpost right down for storage, so that wouldn't work for me.

Use a quick release clamp on the seatpost instead of a Jubilee Clip.

 

[icowden]

Afnug did you read the OP? I have a quick release clamp, it doesn't stop the seatpost slipping - that's the problem!!

Chriscross, I don't have a posh brompton. No tube liners to see here.
Siloch - I might try your approach. I just wiped down with a J-cloth as much as possible. Although the bit of paper is working well at the moment, I don't see it as a permanent solution...

 

[Venod]

Afnug did you read the OP? I have a quick release clamp, it doesn't stop the seatpost slipping - that's the problem!!

Yes I did read the OP, I meant instead of attaching a Jubilee clip around the seatpost (which you would have to slacken with a screwdriver to insert your post for foldiing) use a second quick release that clamps to your seat post (not frame) so enabling to insert the post without tools, so you would have two quick release clamps one above the other but of different internal diameters.
Not a very elegant solution though.

 

[12boy]

I've used the double QR strategy on my Brompton one to hold it in the frame, and a second to keep the post from sliding and it worked fine. I would not do anything to compromise the integrity of the post because at one point I filed a tiny groove on my Brompton seatpost to identify the stopping point. This worked well until the seatpost actually tore right at the mark. Driling holes in the seatpost might not be a good idea.

 

[icowden]

Thanks Afnug - I'm with you now. I'm thinking that I might just have to try to make some sort of permanent very slim shim. The piece of paper worked really well.

Iain