Brompton Seat Post Sleeve Fitting

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Brompton Seat Post Sleeve Fitting

Postby Eddie Miles on Sun Sep 03, 2017 8:08 am

Does anyone know why I can't get a new seat sleeve to fit? I'm replacing a very worn sleeve on an L5 from 1999/2000. I have a replacement sleeve from Brompton that comes with clear instructions. I cut out the old sleeve and the frame tube is now nice and clean. Before gluing, Brompton recommend a 'dry run'; inserting the sleeve and the seat tube and checking for fit. At this point the seat tube just will not fit inside the sleeve when the whole assembly is inserted in the bike frame. It's as if the sleeve is too thick for purpose. If anyone has encountered this before and worked it out then how did you fix it? I would add the following:
1. Yes I thoroughly removed all the old sleeve
2. Yes I'm using the correct pre-2002 sleeve without the upstanding key
3. Yes the lip on the top of the sleeve is engaged with the bead in the frame
4. I don't think that the clamp has been overtightened (pinched) in the past because the same problem occurs if the sleeve and seat post are offered up for fit in the bottom of the frame.
Thanks in advance
Eddie Miles
 
Posts: 5
Joined: Sun Sep 03, 2017 7:51 am

Re: Brompton Seat Post Sleeve Fitting

Postby Eddie Miles on Tue Sep 05, 2017 11:25 am

Apologies but I am answering my own question! Hopefully this will be of assistance to anyone else replacing the sleeve. I decided to figure this out for myself in the end.
Firstly it is understandable that the sleeve design has changed over the years. Since 1999 the length and the moulding pattern on the sleeve reverse has changed. My belief is that because the tolerances are so fine, any slight variation will cause the tube/sleeve/seatpost not to fit. What I did was to ensure that the inside of the seat tube (on the frame) was completely smooth by running a half-round file lightly over the surface and then rubbing down with emery paper. I then offered up the plastic sleeve and tried for fit. Still too tight. I then filed the reverse of the plastic sleeve all round and rubbed down with emery paper. Still too tight. I repeated this until I got the fit I wanted. The gluing operation was simple and this is a 5 minute job once you've spent an hour fettling the plastic sleeve. Finally a note for anyone working on a pre-2002 bike. The spare part(s) from Brompton come as a pack of two sleeves; one pre-2002 and one post-2002. However the older sleeve is just the newer sleeve with the raised key filed off by Brompton. This means that anyone working on an older bike who had a file actually has two sleeves at their disposal. Good to know if you are nervous about filing away too much.
Eddie Miles
 
Posts: 5
Joined: Sun Sep 03, 2017 7:51 am

Re: Brompton Seat Post Sleeve Fitting

Postby buraimo on Fri Sep 08, 2017 7:26 pm

Did you manage to resolve this? I have the same problem. If you managed, I wouild be grateful for advice.

Best wishes,
buraimo
 
Posts: 1
Joined: Fri Sep 08, 2017 7:21 pm

Re: Brompton Seat Post Sleeve Fitting

Postby Eddie Miles on Mon Sep 11, 2017 6:39 am

Yes, following the method above does work. You need patience!
Eddie Miles
 
Posts: 5
Joined: Sun Sep 03, 2017 7:51 am

Re: Brompton Seat Post Sleeve Fitting

Postby Ksamyui on Sun Dec 03, 2017 7:08 am

I’m having the same problem; thanks for concerning sanding is the only way, I thought I was fitting incorrectly. Out of interest which glue did you use?
Ksamyui
 


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