Brittle Days

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Fitting a Brompton chain guard

with 5 comments

I have a Brompton. It is lovely and useful, but the plastic chain guard is a weak spot. It gets squashed in the fold and can be crushed in transportation. Mine was smashed to pieces following a disagreement with a tram track in San Francisco. So I ordered a replacement.

Here is the useful secret that helps make fitting it easier: snap off the 5 large nubbins on the right-hand side (ie the outside) of the guard. Then put it on the chainring, aligning the little tabs with the holes in the chainring.. Then push the snapped-off plastic bits back in. I found it easier to push them in the wrong way round.

Written by tomsulston

27/05/2011 at 18:28

Posted in cycling

5 Responses

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  1. Thanks! I just stared at it for 20 seconds, then typed ‘Brompton chainguard’ into google and got your helpful post.


    08/01/2012 at 20:07

    • One other little piece to clarify this – you will not damage anything by snapping off the 5 little cylinders – they are made as part of the chainguard and unless you snap them off you will find it almost impossible to get them to push into the holes. Once you have them snapped off use a piece of emery paper to smooth the edges that where connected to the chain guard – this will remove the rough plastic and you will find they are very much easier to push into the holes.


      23/10/2012 at 23:45

  2. After struggling with this for entire evening all I succeeded in doing was breaking it. A shocking piece of design.For God’s sake Brompton, either push in the lugs at the factory or come up with a better solution! They should be ashamed of themselves for selling such a shoddy spare part.

    T Hand

    13/01/2013 at 05:49

  3. Typed in Brompton Chainguard and got this thread. Thanks. I had two spare parts on order which arrived promptly from CM Wasson in Palo Alto. The original Brompton spares packet with the Nylon hook at front axle arrived with clear instructions but the packet containing the the chain guard did not. You can guess which part I have just damaged. By the way the part shipped to me is made in France, and may be a standard part at your local bike store. it has a big flat S as manufacturers mark on it and the part number Bte SGBD. It is a good design spoiled by lack of instructions.


    12/02/2013 at 06:04

  4. The Brompton recommendation is to take the chain wheel off lay it flat on the ground with the guard located on top and hit the ‘pins’ with a hammer. I tried all the other methods mentioned and could not get the pins to move without fear of breaking something. I tried it the Brompton way and it took 10 seconds and was very easy. Just a pity it did not come with instructions.

    Alan beveridge

    26/06/2015 at 05:45

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